How can a Mediterranean diet help you? What the research says

A Mediterranean diet is high in vegetables, fruits, whole grains, and olive oil and low in meat, sweets, and saturated fat. It is linked to lower risks of cancer and relief of some symptoms and imbalances common among people with cancer.

How can a Mediterranean diet help you? What the research says

We summarize the clinical evidence for each medical benefit here. We begin with our assessment of the strength of evidence within each category, followed by a brief summary of individual studies or reviews of several studies. In assessing the strength of evidence, we consider the study design, number of participants, and the size of the treatment effect (how much outcomes changed with treatment).

Our assessments of evidence for each medical benefit fall into one of these categories:

Strong evidence: consistent, significant effects in several large (or at least one very large) well designed clinical studies or at least two meta-analysesa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of clinical studies of moderate or better quality (or one large meta-analysis) finding similar results
Good evidence: significant effects in one large or several mid-sized and well-designed clinical studies ( randomized controlled trialsa study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects with an appropriate placebo or other strong comparison control or observational studies that control for confounds)
Modest evidence: significant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies), or several small studies aggregated into a meta-analysis
Preliminary evidence: significant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect
Weak evidence: one or more case studies, supported by animal evidence OR small treatment effects of limited clinical significance OR studies with no controls OR weak trends of effects
Insufficient evidence: preclinical evidence only OR clinical studies with such poor or unclear methodology that no conclusion can be drawn OR conflicting findings across clinical studies with no preponderance of evidence in one direction; conflicting evidence occurs when studies find conflicting effects (positive effect vs no effect or negative effect) with the same treatment and the same general study population (same cancer type, for example)

Learn more about how we research and rate therapies and practices in How We Rate Therapies ›

Due to the nature of studies of lifestyle interventions, several risks of bias exist within the studies about the Mediterranean diet that are nearly impossible to avoid, even within a very well designed study. For example, it is not possible to blind participants to the intervention they are receiving, study groups will likely need to be treated differently beyond just the intervention (they will have to have food prepared for them or be trained in preparing Mediterranean meals), and the sample population will likely be biased towards only people who are already interested in lifestyle interventions. Several researchers have gone to great lengths to minimize these risks of bias but the risk will always be there to some degree. Due to these inherent risks, we consider the highest quality any individual RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects can achieve is “moderate.”

Improving treatment outcomes

Is a Mediterranean diet linked to improved survival? Is it linked to less cancer growth or metastasis? Does it enhance the anticancer action of other treatments or therapies? We present the evidence.

Cancer as a whole

Insufficient evidencepreclinical evidence only OR clinical studies with such poor or unclear methodology that no conclusion can be drawn OR conflicting findings across clinical studies with no preponderance of evidence in one direction; conflicting evidence occurs when studies find conflicting effects (positive effect vs no effect or negative effect) with the same treatment and the same general study population (same cancer type, for example) (this is the CancerChoices definition; other researchers and studies may define this differently) of increased survival among people with cancer with the highest adherence to a Mediterranean diet

Prostate cancer

Weak evidenceone or more case studies, supported by animal evidence OR small treatment effects of limited clinical significance OR studies with no controls OR weak trends of effects (this is the CancerChoices definition; other researchers and studies may define this differently) of lower risk of Gleason grade group progression among men with prostate cancer with each 1-unit increase in adherence to a Mediterranean diet

No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on prostate cancer mortality among people with prostate cancer with the highest adherence to a Mediterranean diet in a large study

Optimizing your body terrain

Does a Mediterranean diet promote an environment within your body that is less supportive of cancer development, growth, or spread? We present the evidence.

Research has only begun studying the connections between body terrain factors and cancer outcomes, and the oncology community is not yet sure how to interpret all the findings. If any of these terrain factors could be an issue for you, we recommend that you ask your doctor if you need any diagnostic tests to detect terrain imbalances or any adjustments to your lifestyle or medications.

Optimizing Your Body Terrain

We also recommend that you share with your doctor the information here about how a Mediterranean diet might affect these terrain factors if you have any imbalances.

Body weight

Good evidence of lower BMI, waist circumference, and/or body weight among people eating a Mediterranean diet

High blood sugar and insulin resistance

Good evidencesignificant effects in one large or several mid-sized and well-designed clinical studies (randomized controlled trials (RCTs) with an appropriate placebo or other strong comparison control or observational studies that control for confounds) (this is the CancerChoices definition; other researchers and studies may define this differently) of better markers of glycemic control among people with type 2 diabetes or other diagnoses eating a Mediterranean diet

Good evidence of lower fasting insulin and homeostatic model assessment of insulin resistance (HOMA-IR) but not HbA1C among people eating a Mediterranean diet

Insufficientpreclinical evidence only OR clinical studies with such poor or unclear methodology that no conclusion can be drawn OR conflicting findings across clinical studies with no preponderance of evidence in one direction; conflicting evidence occurs when studies find conflicting effects (positive effect vs no effect or negative effect) with the same treatment and the same general study population (same cancer type, for example) (this is the CancerChoices definition; other researchers and studies may define this differently) and conflicting evidence of an effect on fasting glucose among people eating a Mediterranean diet

People with type 2 diabetes: good evidence of better markers of glycemic control among people with type 2 diabetes or other diagnoses eating a Mediterranean diet

Better markers of glycemic control (fasting blood glucose and HbA1C) among people with type 2 diabetes eating a Mediterranean diet compared to different diets (low-fat diet, low-carb diet, standard (control) diet, and high-carb diet) in direct and indirect comparisons of a network meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 10 RCTsrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects¹²Pan B, Wu Y et al. The impact of major dietary patterns on glycemic control, cardiovascular risk factors, and weight loss in patients with type 2 diabetes: a network meta-analysis. Journal of Evidence Based Medicine. 2019 Feb;12(1):29-39. or compared to those diets plus vegetarian diet, paleolithic diet, high-protein diet, low glycemic index/glycemic load diet and moderate-carbohydrate diet, but not a low-carb diet which was associated with better fasting glucose but not better HbA1C, in a network analysis of 56 RCTs¹³Schwingshackl L, Chaimani A, Hoffmann G, Schwedhelm C, Boeing H. A network meta-analysis on the comparative efficacy of different dietary approaches on glycaemic control in patients with type 2 diabetes mellitus. European Journal of Epidemiology. 2018;33(2):157-170.
Greater reductions in fasting plasma glucose, HbA1C and fasting insulin among people with type 2 diabetes eating a Mediterranean diet compared to other diets in a meta-analysis of 9 RCTs¹⁴Huo R, Du T et al. Effects of Mediterranean-style diet on glycemic control, weight loss and cardiovascular risk factors among type 2 diabetes individuals: a meta-analysis. European Journal of Clinical Nutrition. 2015 Nov;69(11):1200-8.
Lower marker of overall blood glucose (HbA1C) but no evidence of an effect on fasting blood glucose among people with or at high risk for type II diabetes eating a Mediterranean style diet compared to other diets, except Paleo diet, in a network meta-analysis of 8 controlled trialsa study design in which people are assigned to either an experimental group or a control group to compare the outcomes from different treatment; assignment is not random, and so this is not as strong a study design as a randomized controlled trial, but still stronger than an uncontrolled trial¹⁵Carter P, Achana F et al. Mediterranean diet improves HbA1c but not fasting blood glucose compared to alternative dietary strategies: a network meta-analysis. Journal of Human Nutrition and Dietetics. 2014 Jun;27(3):280-97.
Better fasting blood glucose among people with various diagnoses (pre-diabetes mellitis, pre-hypertension, obesity, metabolic syndrome, cardiovascular disease and risk factors, erectile dysfunction, female sexual dysfunction, non-insulin dependent diabetes mellitis, non-alcoholic fatty liver disease, or no diagnosis) eating a Mediterranean-style diet compared to other diets and controls such as the participants’ regular diet, a low-fat diet, paleo diet, high-saturated fatty acid diet, or western diet in a meta-analysis of 23 intervention trials of moderate quality¹⁶Garcia M, Bihuniak JD et al. The effect of the traditional Mediterranean-style diet on metabolic risk factors: a meta-analysis. Nutrients. 2016;8(3):168.

Not specific to people with diabetes

Good evidence of lower fasting insulin and homeostatic model assessment of insulin resistance (HOMA-IR) but not HbA1C among people eating a Mediterranean diet

Inconsistent evidence of an effect on fasting glucose among people eating a Mediterranean diet

Lower fasting glucose, fasting insulin, and homeostatic model assessment of insulin resistance (HOMA-IR) but not HbA1C among people eating a Mediterranean diet compared to controls in a meta-analysis of 57 controlled trials¹⁷Papadaki A, Nolen-Doerr E et al. The effect of the Mediterranean diet on metabolic health: a systematic review and meta-analysis of controlled trials in adults. Nutrients. 2020;12(11):3342.
No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on fasting blood glucose among people with high adherence to a Mediterranean diet compared to low adherence in meta-analysis of 28 observational studies of mostly satisfactory to high quality¹⁸Bakaloudi DR, Chrysoula L et al. Impact of the level of adherence to Mediterranean diet on the parameters of metabolic syndrome: a systematic review and meta-analysis of observational studies. Nutrients. 2021;13(5):1514.
Lower insulin resistance among people at high risk for cardiovascular disease eating a Mediterranean diet supplemented with either olive oil or tree nuts for 3 months compared to a low-fat diet in a mid-sized RCT¹⁹Estruch R. Anti-inflammatory effects of the Mediterranean diet: the experience of the PREDIMED study. Proceedings of the Nutrition Society. 2010 Aug;69(3):333-40.
Lower glucose and insulin responses after a single meal resembling a Mediterranean diet compared to a typical meal among overweight or obese people, and this effect was stronger after eating a Mediterranean diet for 8 weeks compared to a control group maintaining their regular diet in a small RCT of moderate quality²⁰Vitale M, Giacco R et al. Acute and chronic improvement in postprandial glucose metabolism by a diet resembling the traditional Mediterranean dietary pattern: Can SCFAs play a role? Clinical Nutrition. 2021 Feb;40(2):428-437.
Lower markers of insulin resistance, appetite, and inflammation and improved markers of glucose control among obese or overweight people with low baseline plasma levels of OEA/PEA eating a Mediterranean-style diet without changing calorie intake for 8 weeks compared to baseline in an uncontrolled analysis within a small RCT of low quality²¹Tagliamonte S, Laiola M et al. Mediterranean diet consumption affects the endocannabinoid system in overweight and obese subjects: possible links with gut microbiome, insulin resistance and inflammation. European Journal of Nutrition. 2021;60(7):3703-3716.

Hormone imbalance

No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on daily cortisol patterns among healthy people eating a standardized Mediterranean meal as their first meal of the day in a small study

Immune function

Increased immune system activation is not always beneficial, so your oncology team needs to determine whether immune activation would be favorable in your situation.

Modest evidencesignificant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observational studies), or several small studies aggregated into a meta-analysis (this is the CancerChoices definition; other researchers and studies may define this differently) of better immune function among people eating a Mediterranean diet for several years

Inflammation

Good evidence of lower markers of inflammation such as C-reactive protein (CRP), high sensitivity CRP (hs-CRP), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) among people eating a Mediterranean diet

A weak trendan apparent change due to a therapy, close to but not achieving full statistical significance (this is the CancerChoices definition; other researchers and studies may define this differently toward lower markers of inflammation (CRP) among people with coronary heart disease participating in a Mediterranean diet intervention of training, education or supplied meals compared to controls in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 7 controlled trialsa study design in which people are assigned to either an experimental group or a control group to compare the outcomes from different treatment; assignment is not random, and so this is not as strong a study design as a randomized controlled trial, but still stronger than an uncontrolled trial²⁵Mayr HL, Tierney AC et al. Mediterranean-type diets and inflammatory markers in patients with coronary heart disease: a systematic review and meta-analysis. Nutrition Research. 2018 Feb;50:10-24.
Lower markers of inflammation (CRP, IL-6 and TNF-α) among people with the highest adherence or eating a Mediterranean diet intervention compared to the lowest adherence or controls in a meta-analysis of 4 controlled trials²⁶Papadaki A, Nolen-Doerr E et al. The effect of the Mediterranean diet on metabolic health: a systematic review and meta-analysis of controlled trials in adults. Nutrients. 2020;12(11):3342.
Lower markers of inflammation (CRP) among people 65 years and older with the highest adherence to a Mediterranean diet compared to the lowest in a meta-analysis of 6 observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies²⁷Wu PY, Chen KM, Tsai WC. The Mediterranean dietary pattern and inflammation in older adults: a systematic review and meta-analysis. Advances in Nutrition. 2021;12(2):363-373.
Lower markers of inflammation (cytokines) among people with coronary heart disease eating a Mediterranean diet compared to other diets in a review of 4 observational studies²⁸Mayr HL, Tierney AC et al. Mediterranean-type diets and inflammatory markers in patients with coronary heart disease: a systematic review and meta-analysis. Nutrition Research. 2018 Feb;50:10-24.
Less inflammation among people eating Mediterranean diets compared to a low-fat diet; the benefit was greater when adding nuts in a mid-sized RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects²⁹Casas R, Sacanella E et al. The effects of the Mediterranean diet on biomarkers of vascular wall inflammation and plaque vulnerability in subjects with high risk for cardiovascular disease. A randomized trial. PLoS One. 2014 Jun 12;9(6):e100084.
Lower Dietary Inflammation Index (DII)—associated with lower inflammation markers, lower all cause mortality, and a variety of better health outcomes such as a reduced risk of cardiovascular disease and cancer—among people with the highest adherence to a Mediterranean diet compared to the lowest in a very large and well done observational study³⁰Garcia-Arellano A, Martínez-González MA et al. Dietary inflammatory index and all-cause mortality in large cohorts: the SUN and PREDIMED studies. Clinical Nutrition. 2019 Jun;38(3):1221-1231.
Higher plasma levels of anti-inflammatory bioflavonoids naringin, hesperetin, and hesperidin and lower plasma levels of interleukin-6 among people eating a Mediterranean diet for 12 weeks compared to baseline and compared to controls following their usual diet in a small RCT³¹Al-Aubaidy HA, Dayan A et al. Twelve-week Mediterranean diet intervention increases citrus bioflavonoid levels and reduces inflammation in people with type 2 diabetes mellitus. Nutrients. 2021;13(4):1133.
Lower markers of inflammation (hs CRP) among people with familial hypertension with the highest adherence to a Mediterranean diet compared to the lowest in a small observational study³²Antoniazzi L, Arroyo-Olivares R et al. Adherence to a Mediterranean diet, dyslipidemia and inflammation in familial hypercholesterolemia. Nutrition Metabolism and Cardiovascular Disease. 2021 Jun 30;31(7):2014-2022.
Lower markers of inflammation among people at high risk for cardiovascular disease eating a Mediterranean diet supplemented with either olive oil or tree nuts for 3 months compared to a low-fat diet in a mid-sized RCT³³Estruch R. Anti-inflammatory effects of the Mediterranean diet: the experience of the PREDIMED study. Proceedings of the Nutrition Society. 2010 Aug;69(3):333-40.
Lower markers of inflammation among men with metabolic syndrome eating a Mediterranean diet for 5 weeks compared to a North American control diet, with further improvements among those who also lost weight, in a small RCT³⁴Richard C, Couture P, Desroches S, Lamarche B. Effect of the Mediterranean diet with and without weight loss on markers of inflammation in men with metabolic syndrome. Obesity (Silver Spring). 2013 Jan;21(1):51-7.
Lower markers of inflammation (CRP and TNF-α) among people with type 2 diabetes or cardiovascular risk factors eating a Mediterranean diet compared to a low-fat diet in a subgroup analysis of a small RCT of moderate quality ³⁵Arpón A, Riezu-Boj JI et al. Adherence to Mediterranean diet is associated with methylation changes in inflammation-related genes in peripheral blood cells. Journal of Physiology and Biochemistry. 2016 Aug;73(3):445-455.

Oxidation

Weak evidenceone or more case studies, supported by animal evidence OR small treatment effects of limited clinical significance OR studies with no controls OR weak trends of effects (this is the CancerChoices definition; other researchers and studies may define this differently) of reduced oxidative stress among people eating a Mediterranean diet

No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on an oxidative stress marker (oxidized-LDL cholesterol concentration) among people eating a Mediterranean diet compared to controls in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of one RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects and one controlled triala study design in which people are assigned to either an experimental group or a control group to compare the outcomes from different treatment; assignment is not random, and so this is not as strong a study design as a randomized controlled trial, but still stronger than an uncontrolled trial³⁶Papadaki A, Nolen-Doerr E et al. The effect of the Mediterranean diet on metabolic health: a systematic review and meta-analysis of controlled trials in adults. Nutrients. 2020;12(11):3342.
A weak trendan apparent change due to a therapy, close to but not achieving full statistical significance (this is the CancerChoices definition; other researchers and studies may define this differently toward a lower marker of oxidative stress (8-OHdG) among people with type 2 diabetes eating a Mediterranean diet for 12 weeks compared to controls in a small RCT³⁷Al-Aubaidy HA, Dayan A et al. Twelve-week Mediterranean diet intervention increases citrus bioflavonoid levels and reduces inflammation in people with type 2 diabetes mellitus. Nutrients. 2021;13(4):1133.
Lower oxidized-LDL cholesterol and fewer activated genes associated with the human oxidation pathway (CCL5, UCP2, and DUOX2) among people eating a tocopherol-enriched Mediterranean diet meal compared to a high-fat meal (McDonald’s) in a small RCT³⁸De Lorenzo A, Bernardini S et al. Mediterranean meal versus western meal effects on postprandial ox-LDL, oxidative and inflammatory gene expression in healthy subjects: a randomized controlled trial for nutrigenomic approach in cardiometabolic risk. Acta Diabetologica. 2017 Feb;54(2):141-149.

Your microbiome

Strong evidenceconsistent, significant effects in several large (or at least one very large) well designed clinical studies or at least two meta-analyses of clinical studies of moderate or better quality (or one large meta-analysis) finding similar results (this is the CancerChoices definition; other researchers and studies may define this differently) of an alteration of gut microbiotathe collection of microbes living on and within your body to a status associated with less inflammation, reduced risks of disease, and eubiosisdominance of microbial taxa associated with lower risk of disease in general among people eating a Mediterranean diet

Relatively less abundance of taxa associated with obesity, dysfunctional mucosa, inflammation, and colorectal and gastric cancers, as well as relatively greater abundance of taxa associated with anti-inflammatory effects and short-chain fatty acids among people with high adherence to a Mediterranean diet compared to healthy controls not eating a defined diet or people diagnosed or with increased risk factors for colorectal cancer in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 17 observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies³⁹Illescas O, Rodríguez-Sosa M et al. Mediterranean diet to prevent the development of colon diseases: a meta-analysis of gut microbiota studies. Nutrients. 2021;13(7):2234.
A relative increase in abundance of microbiota associated with a reduced risk in age-related frailty, improved cognitive function, production of short-chain fatty acids (SCFAs) and reduced inflammatory status as well as a relative decrease in abundance of microbiota associated with an increased risk of frailty, worse cognitive function, increased inflammation and chronic diseases such as type 2 diabetes mellitus and colorectal cancer among healthy and pre-frail people than 65 years or older eating a Mediterranean diet for 12 months compared to controls maintaining their standard diet in a large RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects of moderate quality⁴⁰Ghosh TS, Rampelli S et al. Mediterranean diet intervention alters the gut microbiome in older people reducing frailty and improving health status: the NU-AGE 1-year dietary intervention across five European countries. Gut. 2020;69(7):1218-1228.
Greater diversity and greater abundance of taxa associated with increased butyric acid production and better insulin regulation and a lesser abundance of taxa associated with inflammation and colorectal cancer among overweight or obese people eating a Mediterranean diet for 8 weeks compared to a control group maintaining their regular diet in a small RCT of moderate quality⁴¹Vitale M, Giacco R et al. Acute and chronic improvement in postprandial glucose metabolism by a diet resembling the traditional Mediterranean dietary pattern: Can SCFAs play a role? Clinical Nutrition. 2021 Feb;40(2):428-437.
Higher presence of short-chain fatty acids and other components beneficial to health in the fecal microbiome of children eating a Mediterranean diet compared to a Western (USA) diet in a review⁴²Shankar V, Gouda M et al. Differences in gut metabolites and microbial composition and functions between Egyptian and US children are consistent with their diets. mSystems. 2017 Feb 7;2(1). pii: e00169-16.
Greater diversity of intestinal microbiota towards a state that promotes metabolic and cardiovascular health among healthy overweight or obese people with low baseline fruit and vegetable consumption eating a Mediterranean diet tailored to their habitual energy intakes for 4 weeks compared to people following their regular diets in a small RCT of unclear quality⁴³Meslier V, Laiola M et al. Mediterranean diet intervention in overweight and obese subjects lowers plasma cholesterol and causes changes in the gut microbiome and metabolome independently of energy intake. Gut. 2020 Jul;69(7):1258-1268.

Managing side effects and promoting wellness

Is a Mediterranean diet linked to fewer or less severe side effects or symptoms? Is it linked to less toxicity from cancer treatment? Does it support your quality of life or promote general well-being? We present the evidence.

Anxiety

Weak evidenceone or more case studies, supported by animal evidence OR small treatment effects of limited clinical significance OR studies with no controls OR weak trends of effects (this is the CancerChoices definition; other researchers and studies may define this differently) of lower anxiety among people with breast cancer achieving a higher adherence to the Mediterranean diet

Fatigue

Preliminary evidencesignificant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect (this is the CancerChoices definition; other researchers and studies may define this differently) of less cancer-related fatigue during androgen deprivation therapy (ADT) among people with prostate cancer eating a Mediterranean diet

Quality of life and function

Preliminary evidence of better quality of life scores during androgen deprivation therapy (ADT) among people with prostate cancer eating a Mediterranean diet

Symptoms not specific to cancer

Preliminary evidence of lower anxiety scores among people diagnosed with depression receiving training in and adhering to a Mediterranean diet

Preliminary evidence of lower blood pressure among people at high risk for cardiovascular disease eating a Mediterranean diet supplemented with either olive oil or tree nuts

Modest evidencesignificant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observational studies), or several small studies aggregated into a meta-analysis (this is the CancerChoices definition; other researchers and studies may define this differently) of better cognitive scores among people eating a modified Mediterranean diet

Modest evidence of less depression or better mood among people eating a Mediterranean diet

Modest evidence of improved quality of life and function among people eating a Mediterranean diet at midlife or later

Preliminary evidence of less pain among people with stable rheumatoid arthritis eating a Mediterranean diet for 12 weeks

Anxiety: preliminary evidence of lower anxiety scores among people diagnosed with depression receiving training in and adhering to a Mediterranean diet

Lower anxiety scores among people diagnosed with depression receiving training in and adhering to a Mediterranean diet compared to people receiving social support not related to diet education in 2 small RCTsrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects of moderate quality⁴⁷Parletta M, Zarnowiecki D et al. A Mediterranean-style dietary intervention supplemented with fish oil improves diet quality and mental health in people with depression: a randomized controlled trial (HELFIMED). Nutritional Neuroscience; 2019 Jul;22(7):474-487; Jacka FN, O’Neil A et al. A randomised controlled trial of dietary improvement for adults with major depression (the ‘SMILES’ trial. BMC Medicine. 2017;15(1):23, published correction: Jacka FN, O’Neil A et al. Correction to: A randomised controlled trial of dietary improvement for adults with major depression (the ‘SMILES’ trial). BMC Medicine. 2018 Dec 28;16(1):236.

Cardiovascular symptoms: preliminary evidence of lower blood pressure among people at high risk for cardiovascular disease eating a Mediterranean diet supplemented with either olive oil or tree nuts

Lower blood pressure among people at high risk for cardiovascular disease eating a Mediterranean diet supplemented with either olive oil or tree nuts for 3 months compared to a low-fat diet in a mid-sized RCT⁴⁸Estruch R. Anti-inflammatory effects of the Mediterranean diet: the experience of the PREDIMED study. Proceedings of the Nutrition Society. 2010 Aug;69(3):333-40.

Cognitive difficulties: modest evidence of better cognitive scores among people eating a modified Mediterranean diet

Higher scores for memory, frontal, and global cognition among healthy volunteers eating a Mediterranean diet with increased nuts or olive oil compared to people given advice to reduce dietary fat in a mid-sized RCT⁴⁹Valls-Pedret, Aleix Sala-Vila, Dpharm, PhD et al. Mediterranean diet and age-related cognitive decline: a randomized controlled trial. JAMA Internal Medicine. 2015;175(7):1094-1103.
Higher scores on cognitive function tests, improved markers of neuronal function, and increase in the surface area of the inferior frontal gyrus of the brain among healthy middle-aged obese women eating a calorie-restricted modified MIND diet (Mediterranean-DASH Intervention for Neurodegenerative Delay) for 3 months compared to a calorie-restricted standard control diet in a small RCT⁵⁰Arjmand G, Abbas-Zadeh M, Eftekhari MH. Effect of MIND diet intervention on cognitive performance and brain structure in healthy obese women: a randomized controlled trial. Scientific Reports. 2022;12(1):2871.
Better memory recall, higher alertness and contentment scores, and less confusion after 10 days among healthy people eating a Mediterranean diet compared to the normal diet in a small controlled triala study design in which people are assigned to either an experimental group or a control group to compare the outcomes from different treatment; assignment is not random, and so this is not as strong a study design as a randomized controlled trial, but still stronger than an uncontrolled trial of moderate quality⁵¹Lee J, Pase M. Switching to a 10-day Mediterranean-style diet improves mood and cardiovascular function in a controlled crossover study. Nutrition. 2015 May;31(5):647-52.
Better cognitive scores for processing speed but not other cognitive functions among people with multiple cardiovascular risk factors eating a Mediterranean diet altered for either increased pork⁵²Wade AT, Davis CR et al. A Mediterranean diet with fresh, lean pork improves processing speed and mood: cognitive findings from the medpork randomised controlled trial. Nutrients. 2019;11(7):1521. or increased dairy⁵³Wade AT, Davis CR et al. A Mediterranean diet supplemented with dairy foods improves mood and processing speed in an Australian sample: results from the MedDairy randomized controlled trial. Nutritional Neuroscience. 2020 Aug;23(8):646-658. compared to a low-fat diet in small controlled trials

Depression and mood: modest evidence of less depression or better mood among people eating a Mediterranean diet

Less depression and mood disturbance among people with multiple cardiovascular risk factors eating a Mediterranean diet altered for increased dairy compared to a low-fat diet in a small controlled trial⁵⁴Wade AT, Davis CR et al. A Mediterranean diet supplemented with dairy foods improves mood and processing speed in an Australian sample: results from the MedDairy randomized controlled trial. Nutritional Neuroscience. 2020 Aug;23(8):646-658.
Fewer symptoms of depression among people eating a Mediterranean diet compared to a standard diet in a large meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 6 observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies⁵⁵Nicolaou M, Colpo M et al. Association of a priori dietary patterns with depressive symptoms: a harmonised meta-analysis of observational studies. Psychological Medicine. 2020 Aug;50(11):1872-1883.
Lower incidence of high depressive symptoms over a period of 5 to 6 years among people eating a Mediterranean diet compared to a standard diet in a meta-analysis of 3 observational studies⁵⁶Nicolaou M, Colpo M et al. Association of a priori dietary patterns with depressive symptoms: a harmonised meta-analysis of observational studies. Psychological Medicine. 2020 Aug;50(11):1872-1883.
Lower depression scores among people eating a Mediterranean diet compared to other people only in a meta-analysis of 9 cross-sectional studies but no evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. in a meta-analysis of 4 observational studies⁵⁷Shafiei F, Salari-Moghaddam A et al. Adherence to the Mediterranean diet and risk of depression: a systematic review and updated meta-analysis of observational studies. Nutrition Reviews. 2019 Apr 1;77(4):230-239.
Lower depression incidence among those with the highest adherence to the Mediterranean diet compared to the lowest adherence in a meta-analysis of 7 observational studies⁵⁸Lassale C, Batty GD et al. Healthy dietary indices and risk of depressive outcomes: a systematic review and meta-analysis of observational studies. Molecular Psychiatry. 2019;24(7):965-986.

Quality of life and function: Modest evidence of improved quality of life and function among people eating a Mediterranean diet at midlife or later

Lower risk of frailty or pre-frailty among physicians 60 years old or older with the highest adherence to a Mediterranean diet compared to the lowest in a large observational study⁵⁹Ward RE, Orkaby AR et al. Association between diet quality and frailty prevalence in the Physicians’ Health Study. Journal of the American Geriatrics Society. 2020;68(4):770-776.
Higher incidence of healthy aging (no major chronic illnesses including cancer, good physical and cognitive functioning, independence in activities of daily living, good social functioning, no depressive symptoms, good self perceived health and no function limiting pain) among people aged 45–60 years with a higher adherence to a Mediterranean diet compared to lower adherence in a large observational study⁶⁰Assmann KE, Adjibade M et al. Association between adherence to the Mediterranean diet at midlife and healthy aging in a cohort of French adults. Journal of Gerontology Series A: Biological Sciences and Medical Sciences. 2018 Mar 2;73(3):347-354.

Pain: preliminary evidence of less pain among people with stable rheumatoid arthritis eating a Mediterranean diet for 12 weeks

Lower self reported pain and rheumatoid arthritis activity scores among people with stable rheumatoid arthritis eating a Mediterranean diet for 12 weeks compared to controls eating their current diets in a small RCT of moderate quality⁶¹Sköldstam L, Hagfors L et al. An experimental study of a Mediterranean diet intervention for patients with rheumatoid arthritis. Annals of Rheumatic Disease. 2003;62(3):208-214.

Mediterranean diet as part of a combination therapy

Preliminary evidence of greater reduction in depression scores among people achieving higher MedDiet scores and taking fish oil supplements

Preliminary evidence of less pain among people with rheumatoid arthritis attending weekly sessions including cooking classes

Fish oil supplements: preliminary evidence of greater reduction in depression scores among people achieving higher MedDiet scores and taking fish oil supplements

Greater reduction in depression scores among people attending Mediterranean-style cooking classes, achieving higher MedDiet scores, and taking fish oil supplements compared to those attending social gatherings not centered around cooking in a mid-sized RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects of moderate quality⁶²Parletta N, Zarnowiecki D et al. A Mediterranean-style dietary intervention supplemented with fish oil improves diet quality and mental health in people with depression: a randomized controlled trial (HELFIMED). Nutritional Neuroscience. 2019 Jul;22(7):474-487.

Educational classes: preliminary evidence of less pain among people with rheumatoid arthritis attending weekly sessions including cooking classes

Less pain and stiffness, lower systolic blood pressure, and higher weekly total fruit, vegetable, and legume consumption and improvement in the ratio of monounsaturated:saturated fat among people with rheumatoid arthritis living in socially deprived areas attending weekly 2-hour sessions for 6 weeks in the local community, including hands-on cooking classes on a Mediterranean-type diet backed up with written information compared to dietary written information only in a mid-sized controlled triala study design in which people are assigned to either an experimental group or a control group to compare the outcomes from different treatment; assignment is not random, and so this is not as strong a study design as a randomized controlled trial, but still stronger than an uncontrolled trial⁶³McKellar G, Morrison E et al. A pilot study of a Mediterranean-type diet intervention in female patients with rheumatoid arthritis living in areas of social deprivation in Glasgow. Annals of the Rheumatic Diseases. 2007 Sep;66(9):1239-43.

Reducing cancer risk

Is a Mediterranean diet linked to lower risks of developing cancer or of recurrence? We present the evidence.

Cancer as a whole

Good evidencesignificant effects in one large or several mid-sized and well-designed clinical studies (randomized controlled trials (RCTs) with an appropriate placebo or other strong comparison control or observational studies that control for confounds) (this is the CancerChoices definition; other researchers and studies may define this differently) of lower risk of cancer or mortality among people without cancer at baseline with higher adherence to a Mediterranean diet

Lower risk of cancer as a whole among people with higher adherence to a Mediterranean diet compared to other people in a very large meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of meta-analyses of observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies and RCTsrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects⁶⁴Dinu M, Pagliai G et al. Mediterranean diet and multiple health outcomes: an umbrella review of meta-analyses of observational studies and randomised trials. European Journal of Clinical Nutrition. 2018 Jan;72(1):30-43.
Lower cancer mortality but no evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on risk of recurrence among people with the highest adherence to a Mediterranean diet compared to the lowest adherence in a meta-analysis of 14 observational studies⁶⁵Schwingshackl L, Schwedhelm C et al. Adherence to Mediterranean diet and risk of cancer: an updated systematic review and meta-analysis. Nutrients. 2017 Sep 26;9(10):1063.
Lower cancer mortality among people without cancer at baseline with the highest adherence to Mediterranean diet compared to the lowest in a meta-analysis of 18 observational studies of moderate quality overall but not in 1 RCT of low quality⁶⁶Morze J, Danielewicz A et al. An updated systematic review and meta-analysis on adherence to Mediterranean diet and risk of cancer. European Journal of Nutrition. 2021;60(3):1561-1586.
No evidence of an effect on cancer-specific mortality although lower all-cause mortality among people 65 years or older with the highest adherence to the Mediterranean diet compared to the lowest in a large observational study⁶⁷Bonaccio M, Di Castelnuovo A et al. Mediterranean diet and mortality in the elderly: a prospective cohort study and a meta-analysis. British Journal of Nutrition. 2018 Oct;120(8):841-854.

Bladder cancer

Modest evidencesignificant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observational studies), or several small studies aggregated into a meta-analysis (this is the CancerChoices definition; other researchers and studies may define this differently) of lower risk of bladder cancer among people with the highest adherence to the Mediterranean diet

Breast cancer

Good evidence of lower risk of breast cancer among people with the highest adherence to a Mediterranean diet, although the effect may vary with the specific types of breast cancer

Lower risk of invasive breast cancer among women with risk factors for cardiovascular disease eating a Mediterranean diet compared to controls advised to follow a low fat diet in a large RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects of moderate quality⁶⁹Toledo E, Salas-Salvadó J et al. Mediterranean diet and invasive breast cancer risk among women at high cardiovascular risk in the PREDIMED trial: a randomized clinical trial. JAMA Internal Medicine. 2015 Nov;175(11):1752-1760.
Lower risk of breast cancer among people with the highest adherence to a Mediterranean diet compared to the lowest in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 23 observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies and supported by a single RCT⁷⁰Morze J, Danielewicz A et al. An updated systematic review and meta-analysis on adherence to Mediterranean diet and risk of cancer. European Journal of Nutrition. 2021;60(3):1561-1586.
Lower risk of ER-negative breast cancer and a weak trendan apparent change due to a therapy, close to but not achieving full statistical significance (this is the CancerChoices definition; other researchers and studies may define this differently toward a lower risk of other types of breast cancer among people with the highest adherence to a Mediterranean diet compared to the lowest in a large, well done observational study and supported by a meta-analysis of 6 additional observational studies⁷¹van den Brandt PA, Schulpen M. Mediterranean diet adherence and risk of postmenopausal breast cancer: results of a cohort study and meta-analysis. International Journal of Cancer. 2017 May 15;140(10):2220-2231.
Lower risk of invasive ductal carcinomas and lobular breast carcinomas among people with the highest adherence to a Mediterranean diet compared to the lowest in a meta-analysis of 7 observational studies⁷²Dianatinasab M, Rezaian M et al. Dietary patterns and risk of invasive ductal and lobular breast carcinomas: a systematic review and meta-analysis. Clinical Breast Cancer. 2020 Aug;20(4):e516-e528.

Colorectal cancer

Modest evidence of lower risk of colorectal cancer among people with the highest adherence to a Mediterranean diet

Lower risk of colorectal cancer among people with the highest adherence to a Mediterranean diet compared to the lowest in very large meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 117⁷³Morze J, Danielewicz A et al. An updated systematic review and meta-analysis on adherence to Mediterranean diet and risk of cancer. European Journal of Nutrition. 2021;60(3):1561-1586. and 16⁷⁴Moazzen S, van der Sloot KWJ et al. Systematic review and meta-analysis of diet quality and colorectal cancer risk: is the evidence of sufficient quality to develop recommendations? Critical Review of Food Science Nutrition. 2021;61(16):2773-2782. observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies of moderate to very low quality, and a pooled analysis of 9 controlled trialsa study design in which people are assigned to either an experimental group or a control group to compare the outcomes from different treatment; assignment is not random, and so this is not as strong a study design as a randomized controlled trial, but still stronger than an uncontrolled trial of moderate to low quality⁷⁵Bloomfield HE, Koeller E et al. Effects on health outcomes of a Mediterranean diet with no restriction on fat intake: a systematic review and meta-analysis. Annals of Internal Medicine. 2016 Oct 4;165(7):491-500.
Lower risk of rectal cancer and a weak trendan apparent change due to a therapy, close to but not achieving full statistical significance (this is the CancerChoices definition; other researchers and studies may define this differently toward a lower risk of colon cancer, but no evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on colorectal cancer-specific mortality, among people without cancer at baseline with the highest adherence to a Mediterranean diet compared to the lowest in a meta-analysis of 9 observational studies⁷⁶Zhong Y, Zhu Y et al. Association between Mediterranean diet adherence and colorectal cancer: a dose-response meta-analysis. American Journal of Clinical Nutrition. 2020 Jun 1;111(6):1214-1225.
A weak trend toward lower colorectal cancer-specific mortality among people with the highest adherence to the Mediterranean diet compared to the lowest in a meta-analysis of 3 observational studies of high quality⁷⁷Zhong Y, Zhu Y et al. Association between Mediterranean diet adherence and colorectal cancer: a dose-response meta-analysis. American Journal of Clinical Nutrition. 2020 Jun 1;111(6):1214-1225.

Gastrointestinal cancer

Modest evidence of lower risk of upper gastrointestinal cancers as a whole

No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on risk of esophageal cancer among people with the highest adherence to a Mediterranean diet in a combined analysis of studies

Modest evidence of lower risk of liver cancer among people with the highest adherence to a Mediterranean diet

Gynecological cancer

No evidence of an effect on risk of endometrial cancer among people with the highest adherence to a Mediterranean diet in a combined analysis of studies

Head and neck cancer

Modest evidence of lower risk of head and neck cancers among people with the highest adherence to a Mediterranean diet

Leukemia

No evidence of an effect on the risk of chronic lymphocytic leukemia (CLL) among people with the highest adherence to the Mediterranean diet in a large study

Lung cancer

Good evidence of lower risk of lung cancer, stronger among people who smoke heavily and perhaps stronger among men, among people with the highest adherence to a Mediterranean diet

Ovarian cancer

No evidence of an effect on risk of ovarian cancer among people with the highest adherence to a Mediterranean diet in a large study

Pancreatic cancer

Weak evidenceone or more case studies, supported by animal evidence OR small treatment effects of limited clinical significance OR studies with no controls OR weak trends of effects (this is the CancerChoices definition; other researchers and studies may define this differently) of lower risk of pancreatic cancer among those with the highest adherence to a Mediterranean diet

Prostate cancer

Insufficient evidencepreclinical evidence only OR clinical studies with such poor or unclear methodology that no conclusion can be drawn OR conflicting findings across clinical studies with no preponderance of evidence in one direction; conflicting evidence occurs when studies find conflicting effects (positive effect vs no effect or negative effect) with the same treatment and the same general study population (same cancer type, for example) (this is the CancerChoices definition; other researchers and studies may define this differently) of lower risk of prostate cancer among people with the highest adherence to the Mediterranean diet

Keep reading about a Mediterranean diet

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Authors

Andrew Jackson, ND

Research Associate

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Nancy Hepp, MS

Lead Researcher and Program Manager

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Curator and reviewer

Laura Pole, RN, MSN, OCNS

Senior Clinical Consultant

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Last update: May 8, 2023

Last full literature review: November 2021

CancerChoices provides information about integrativein cancer care, a patient-centered approach combining the best of conventional care, self care and evidence-informed complementary care in an integrated plan cancer care. We review complementaryin cancer care, complementary care involves the use of therapies intended to enhance or add to standard conventional treatments; examples include supplements, mind-body approaches such as yoga or psychosocial therapy, and acupuncture therapies and self-care lifestyle actions and behaviors that may impact cancer outcomes; examples include eating health-promoting foods, limiting alcohol, increasing physical activity, and managing stress practices to help patients and professionals explore and integrate the best combination of conventionalthe cancer care offered by conventionally trained physicians and most hospitals; examples are chemotherapy, surgery, and radiotherapy and complementary therapies and practices for each person.

Our staff have no financial conflicts of interest to declare. We receive no funds from any manufacturers or retailers gaining financial profit by promoting or discouraging therapies mentioned on this site.

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BCCT/CancerChoices Take: MEAL Study: Effect of Eating Vegetables on Prostate Cancer Progression

References[+]

Mediterranean Diet

How can a Mediterranean diet help you? What the research says

Improving treatment outcomes

Optimizing your body terrain

Optimizing Your Body Terrain

Managing side effects and promoting wellness

Reducing cancer risk

Keep reading about a Mediterranean diet

Authors

Andrew Jackson, ND

Nancy Hepp, MS

Curator and reviewer

Laura Pole, RN, MSN, OCNS

Learn more

Self Care

Yoga

BCCT/CancerChoices Take: MEAL Study: Effect of Eating Vegetables on Prostate Cancer Progression