Can Mediterranean Diet Reduce Your Chances of Becoming Blind?

Better adherence to a Mediterranean diet reduces the risk of developing age-related macular degeneration, according to a study reported in 2016 in Ophthalmology.

 

Background: Macular degeneration is the leading cause of vision loss, affecting more than 10 million Americans – more than cataracts and glaucoma combined. At present, it is considered incurable. One can compared the human eye to a camera, with the macula the central and most sensitive area of the so-called film. When it is working properly the macula collects highly detailed images at the center of your field of vision and sends the information up the optic nerve to the brain, where we interpret the signals as sight. When the cells of the macula deteriorate, images are not received correctly. While early macular degeneration may not affect your vision, as the disease progresses, you may experience wavy or blurred vision. If the condition continues to worsen, central vision may be completely lost (although peripheral vision may be retained). A Mediterranean diet has been inversely associated with heart attack, stroke, cancer, and mortality. But what about eye health, including macular degeneration?

The Study: Researchers evaluated 5060 patients aged 65 years or older, chosen randomly from centers in Norway, Estonia, the United Kingdom, France, Italy, Greece, and Spain between 2001 and 2002. Dietary intake during the previous 12 months was evaluated, which captured information about consumption of items such as olive oil, fish, wine, fruit, legumes, and meat/meat products. All patients had eye exams, including digital retinal photographs, and blood samples were collected to evaluate antioxidant levels (including lutein, zeaxanthin, carotene, and lycopene). In addition, information was collected regarding smoking and alcohol use and environmental exposure. The mean age among participants was 73.6 years, and 55% were women.

Results: The researchers found that, among the 4753 participants with full dietary data, individuals with a high adherence to a Mediterranean diet had the lowest odds of neovascular advanced macular degeneration, dropping their risk by about half.

My Take:  We cannot establish causality between consuming a Mediterranean diet and the risk of macular degeneration. In addition, self-reporting of dietary information may lead to bias. Still, given the good effects of the diet on the risk of heart attack stroke, and cancer, I am gonna go have some Italian food! I’m Dr. Michael Hunter.

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The small print: The material presented herein is informational only, and is not designed to provide specific guidance for an individual. Please check with a valued health care provider with any questions or concerns. As for me, I am a Harvard- , Yale- and UPenn-educated radiation oncologist, and I practice in the Seattle, WA (USA) area. I feel genuinely privileged to be able to share with you. If you enjoyed today’s offering, please consider clicking the follow button at the bottom of this page.

References: Ophthalmology. Published online November 5, 2016; https://www.macular.org/what-macular-degeneration

Mediterranean Diet has Marked Impact on Aging

Background: The Mediterranean diet consistently has been linked with an array of health benefits, including decreased risk of chronic disease and cancer. Until now, however, no studies had associated the diet with longer telomeres, one of the biomarkers of aging.

Telomeres are repetitive DNA sequences at the ends of chromosomes that get shorter every time a cell divides. Shorter telomeres have been associated with decreased life expectancy and increased risk of aging-related disease (including cancer), while longer telomeres have been linked to longevity. Telomere shortening is accelerated by stress and inflammation, and scientists have speculated that adherence to the Mediterranean diet may help protect against that effect.

The Evidence: In a study published Tuesday online in The British Medical Journal, researchers at Harvard-affiliated Brigham and Women’s Hospital (BWH) found that greater adherence to the Mediterranean diet correlated with longer telomeres.

“To our knowledge this is the largest population-based study specifically addressing the association between Mediterranean diet adherence and telomere length in healthy, middle-aged women,” explained Immaculata De Vivo, an associate professor in the Channing Division of Network Medicine at BWH and the Harvard T.H. Chan School of Public Health, the senior author of this study. “Our results further support the benefits of adherence to this diet to promote health and longevity.”

The researchers analyzed 4,676 disease-free women from the Nurses’ Health Study who had completed the food-frequency questionnaire and whose telomere lengths had been measured. They found that a greater adherence to the Mediterranean diet was associated with longer telomeres, and that even small changes in diet made a difference.

“Our findings showed that healthy eating, overall, was associated with longer telomeres. However, the strongest association was observed among women who adhered to the Mediterranean diet,” explained Marta Crous Bou, a postdoctoral fellow in the Channing Division of Network Medicine and the first author of the study.

De Vivo notes that future research should be aimed at determining which components of the Mediterranean diet drive this association. This would allow researchers to gain insight into the biological mechanism, as well as provide a basis for increased public education for informed lifestyle choices.

My Take: How wonderful that we may be able to slow the aging clock with a healthy diet. But don’t forget physical activity (such as a brisk walk for 30 minutes, 5 times per week), as it too may slow telomere shortening and add to your life expectancy and overall health. I’m Dr. Michael Hunter. Ciao!

Reference: Harvard Gazette 02 December 2014

Mediterranean Diet Improves Cognition

Greek food Mediterranean diet Greece

Background: Previous observational studies reported beneficial effects of the Mediterranean diet (MedDiet) on cognitive function, but results were inconsistent. This study assessed the effect on cognition of a nutritional intervention using MedDiets in comparison with a low-fat control diet.

Methods Researchers examined 522 participants at high vascular risk (age 74.6 ± 5.7 years at cognitive evaluation) enrolled in a multicenter, randomised, primary prevention trial, after a nutritional intervention comparing two Mediterranean diets (supplemented with either extra-virgin olive oil (EVOO) or mixed nuts) versus a low-fat control diet. Global cognitive performance was examined by Mini-Mental State Examination (MMSE) and Clock Drawing Test after 6.5 years of nutritional intervention. Researchers who assessed the outcome were blinded to group assignment. Researchers used general linear models to control for potential confounding.

Results After adjustment for sex, age, education, Apolipoprotein E genotype, family history of cognitive impairment/dementia, smoking, physical activity, body mass index, hypertension, dyslipidaemia, diabetes, alcohol and total energy intake, participants allocated to the MedDiet+EVOO showed higher mean MMSE and CDT scores with significant differences versus control These results did not differ after controlling for incident depression.

What You Need to Know An intervention with a Mediterranean diet enhanced with either extra-virgin olive oil or nuts appears to improve brain function (cognition) compared with a low-fat diet. I’m Dr. Michael Hunter.

The small print: The material presented herein is informational only, and is not designed to provide specific guidance for an individual. Please check with a valued health care provider with any questions or concerns. As for me, I am a Harvard- , Yale- and UPenn-educated radiation oncologist, and I practice in the Seattle, WA (USA) area. I feel genuinely privileged to be able to share with you. If you enjoyed today’s offering, please consider clicking the follow button at the bottom of this page.

Available now: Understand Colon Cancer in 60 Minutes; Understand Brain Glioma in 60 Minutes. Both can be found at the Apple Ibooks store. Coming Soon for iPad:  Understand Breast Cancer in 60 Minutes; Understand Colon Cancer in 60 Minute; Understand Colon Cancer in 60 Minutes; Understand Brain Glioma in 60 Minutes. Thank you.

Reference: J Neurol Neurosurg Psychiatry. 2013;84(12):1318-1325.

Nut Consumption Linked to Lower Mortality

nuts cashews hazelnuts and almonds

The frequency of nut consumption was inversely associated with total and cause-specific mortality independent of other predictors of death, according to a study from 2 large prospective US cohorts, published in the November 21 issue of the New England Journal of Medicine.

“Nuts are rich in nutrients, such as unsaturated fatty acids, fiber, vitamins, and minerals, which may confer cardioprotective, anticarcinogenic, antiinflammatory, and antioxidant properties,” lead author Ying Bao, MD, ScD, associate epidemiologist and instructor in medicine, Brigham and Women’s Hospital and Harvard Medical School, Channing Division of Network Medicine, Boston, Massachusetts. “Previous studies have shown that nut consumption has beneficial effects on various mediators of chronic diseases (eg, blood cholesterol, inflammation, and insulin resistance), and increased nut intake is associated with reduced risks of many chronic diseases (eg, coronary heart disease and type 2 diabetes mellitus).”

The Study: The investigators studied the association between nut intake and mortality among 76,464 women in the Nurses’ Health Study (1980 – 2010) and 42,498 men in the Health Professionals Follow-up Study (1986 – 2010). The authors excluded participants with a history of cancer, heart disease, or stroke. They evaluated nut consumption at baseline and every 2 to 4 years thereafter. During 3,038,853 person-years of follow-up,16,200 women and 11,229 men died.

Compared with participants who did not eat nuts at all, those who ate nuts less than once per week had a 7% decrease in mortality risk, after adjustment for other known or suspected risk factors, including total sodium intake, adherence to a Mediterranean diet, and olive oil intake. Pooled multivariate HRs were 0.89 (95% CI, 0.86 – 0.93) for eating nuts once per week, 0.87 (95% CI, 0.83 – 0.90) for 2 to 4 times per week, 0.85 (95% CI, 0.79 – 0.91) for 5 to 6 times per week, and 0.80 (95% CI, 0.73 – 0.86) for 7 or more times per week (P < .001 for trend).

There were also significant inverse associations between nut consumption and deaths resulting from cancer, heart disease, and respiratory disease. Results were similar for peanuts and tree nuts, and the inverse association persisted across all subgroups.

“In two large prospective U.S. cohorts, we found a significant, dose-dependent inverse association between nut consumption and total mortality, after adjusting for potential confounders,” the authors write. “[C]ompared with participants who did not eat nuts, those who consumed nuts seven or more times per week had a 20% lower death rate.”

Study Strengths and Limitations: Study strengths include prospective design, large sample size (more than 27,000 deaths), 30 years of follow-up with a follow-up rate exceeding 90%, repeated assessment of diet and lifestyle variables (including separate data on peanuts and tree nuts), and extensive data on known or suspected confounding variables.

“Given the observational nature of our study, it is not possible to conclude that the observed inverse association between nut consumption and mortality reflects cause and effect,” the authors write. “However, our data are consistent with a wealth of existing observational and clinical-trial data in supporting the health benefits of nut consumption for many chronic diseases. In addition, nutrients in nuts, such as unsaturated fatty acids, high-quality protein, fiber, vitamins (e.g., folate, niacin, and vitamin E), minerals (e.g., potassium, calcium, and magnesium), and phytochemicals (e.g., carotenoids, flavonoids, and phytosterols), may confer cardioprotective, anticarcinogenic, antiinflammatory, and antioxidant properties.”

Other study limitations include reliance on self-report, possible underestimation of the association, lack of data on method of nut preparation, and restriction of the study sample to health professionals, which could limit generalizability of the results.

I usually offer my take in these blogs, but the author says it best: “[C]linical trials have shown that nut consumption has beneficial effects on some intermediate markers of chronic diseases, such as high cholesterol levels, oxidation, endothelial dysfunction, hyperglycemia, and insulin resistance,” the authors write. “Moreover, recent findings from the [Prevención con Dieta Mediterránea (PREDIMED)] trial [ N Engl J Med. 2013;368:1279-1290] have shown a protective effect of a Mediterranean diet against cardiovascular disease, and one component of the diet was the availability of an average of 30 g of nuts per day.”

Dr. Bao added, “A reasonable recommendation would be to follow the [USDA] Dietary Guidelines, and adding nuts to daily diet may also be beneficial.”

I’m Dr. Michael Hunter.

The small print: The material presented herein is informational only, and is not designed to provide specific guidance for an individual. Please check with a valued health care provider with any questions or concerns. As for me, I am a Harvard- , Yale- and UPenn-educated radiation oncologist, and I practice in the Seattle, WA (USA) area. I feel genuinely privileged to be able to share with you. If you enjoyed today’s offering, please consider clicking the follow button at the bottom of this page.

Available now: Understand Colon Cancer in 60 Minutes; Understand Brain Glioma in 60 Minutes. Both can be found at the Apple Ibooks store. Coming Soon for iPad:  Understand Breast Cancer in 60 Minutes; Understand Colon Cancer in 60 Minute; Understand Colon Cancer in 60 Minutes; Understand Brain Glioma in 60 Minutes. Thank you.

Reference: N Engl J Med. 2013;369:2001-2011.