Mediterranean Diet Benefits Cognitive Decline, Alzheimer’s
Research is confirming that the Mediterranean Diet improves cognition and also helps prevent Alzheimer’s disease.
In this article
Med diet slows cognitive decline
Harvard University researchers followed 16,058 women over the age of 70 years old for six years. Their diets were followed for more than 13 years, as part of the Nurses’ Health Study.
For six of those years, the researchers conducted phone interviews with each four times a year. These tested their cognitive status using the Telephone Interview for Cognitive Status (TICS) test. This tests cognition skills using memory recall, fluency and attention span tests.
The researchers found that those women who ate closest to a Mediterranean diet had significantly better cognitive scores as the women grew older. The differences in their cognitive scores calculated to about one to 1.5 years of aging – meaning the Med diet slowed their aging decline in cognition.
Nuts help slow cognitive decline
Another study by different researchers from Harvard University and Brigham and Women’s Hospital confirmed that eating more nuts every day will increase cognitive skills among women.
Using the same Nurses study as a foundation, the researchers followed 16,010 women 70 years old or older. In this study, 15,467 completed the final cognitive interview. And the TICS cognitive skills testing was utilized.
The researchers found those women who consumed at least five servings of nuts per week had higher cognitive scores compared to those who did not consume nuts. (Most nut serving sizes are about one ounce – about a small handful). The average difference in scores was 0.08 units, which is equivalent to two years of cognition decline during the aging process.
They could not correlate cognitive decline with long-term nut consumption, but the association was clear, as concluded by the researchers:
“Higher nut intake may be related to better overall cognition at older ages, and could be an easily-modifiable public health intervention.”
Mediterranean Diet reduces Alzheimer’s Risk
Researchers from Spain’s University of Navarra have conducted a series of studies that have determined that a Mediterranean diet supplemented with either nuts or extra virgin olive oil results in a reduced risk of mild cognitive impairment (MCI) – and thus Alzheimer’s disease. Another study found that the Med diet with olive oil decreased the risk of MCI even further.
In the major study, 522 elderly adults participated. They had an average age of 75 years. They were split into three groups and followed for six and a half years. One group consumed a standard (Western) low-fat diet, another group consumed a Mediterranean diet supplemented with mixed nuts, and the third group consumed a Mediterranean diet supplemented with virgin olive oil.
The supplemented nuts group consumed 30 grams of mixed nuts per day in addition to their diets, and the supplemented olive oil group consumed one liter of extra virgin olive oil per week.
The subjects were evaluated using the Mini-Mental State Examination and Clock Drawing Test. The Mini-mental exam is a 30-point test used by doctors to check patients for dementia and cognitive impairment. The Clock Drawing Test uses clock drawings to test the patient’s ability to accurately convert, copy and understand – another test for dementia and cognitive impairment.
After the almost seven years, the researchers found that those who ate the Mediterranean Diet with the olive oil had 62% better scores on the Mini-Mental exam than did the control group. This group also had an average of 51% better scores on the Clock Drawing Test. The group consuming the Mediterranean Diet supplemented with nuts had 57% better scores than the conventional diet on the Mini-Mental exam, and 33% better scores on the Clock Drawing Test.
Cognitive impairment is a symptom of Alzheimer’s disease.
Olive Oil Particularly Good for Cognition
Within the same series, the researchers also conducted a study with 285 people. Again, the subjects were divided into three equal and randomized groups.
Before and after the study, the patients were tested for cognition, which included memory testing and language fluency testing using a 14-point questionnaire. Their diets were also carefully validated using food extensive questionnaires.
The researchers found that the Mediterranean diet group that consumed the extra olive oil had a 66% reduced incidence of mild cognitive impairment at the end of the period compared to the control group – the conventional low-fat diet group.
And like the first study, this was after removing many other possible factors, such as smoking, alcohol intake, weight, diabetes and many others.
Mediterranean Diet and verbal fluency
The Mediterranean Diet contains higher levels of fruits and vegetables, whole grains, and little or no red meat.
The olive oil result confirms another study done in 2009, where researchers from France’s University of Montpellier followed 6,947 people, and found that consuming more olive oil resulted in a 17% reduction in cognitive decline and a 15% reduction of verbal fluency decline.
Olive oil is one of the healthiest oils because olives contain a number of medicinal phytonutrients. These include oleuropein, an antioxidant and anticancer agent shown to reduce blood pressure and inflammation. We reported on oleuropein’s anti-cancer ability in another article. Other olive phytonutrients include hydroxytyrosol, tyrosol and verbascoside.
Extra-virgin is important for olive oil because this means the olives are freshly pressed without introducing heat into the process. The olives are being mechanically pressed, and there is no heating or addition of extraction chemicals into the process. This results in more polyphenol content within the olive oil.
Contrasting this, most nuts are roasted or boiled. This addition of heat can destroy many of their medicinal qualities. Besides this, while nuts are extremely nutritious, most nuts do not contain the antioxidant capacity of olives. Other research shows this same benefit of the Med diet with nuts.
Med diet better than supplements for Alzheimer’s
If you were hoping to replace a good diet with a blend of multivitamin supplements for cognitive health, you might be missing the big picture. The reality is that diet helps prevent Alzheimer’s disease, but not so much for multivitamin supplements.
A 2012 paper out of Harvard Medical School states that supplements outside of vitamin E have failed to prove any benefit or prevention for Alzheimer’s disease – but diet and exercise do.
The paper comes from the 2012 December’s issue of Harvard Men’s Health Watch, which focused upon the findings of Dr. Gad Marshall, a Harvard Alzheimer’s researcher and Assistant Professor of Medicine at Harvard. Dr. Marshall contends that the major supplements people ask about – including B vitamins, Vitamin C, Co-enzyme Q10, Huperzine A, Ginko biloba, Fish oil, Curcumin and Coconut oil have yet to be proven to slow cognitive decline or prevent Alzheimer’s disease.
“There are a lot of things out there for which we have no data on whether they are safe or do anything to help,” said Dr. Marshall. “My patients and their families ask a lot about supplements, and I try to point them to whatever evidence we have.”
According to Dr. Marshall, only vitamin E has shown any promise to preserving improving memory among supplements. “There have been several studies showing that at these high doses there was a small increase in the death rate,” he said. But he added that large dose vitamin E supplementation also can come with safety issues. “Vitamin E at doses higher than 400 international units (IU) per day is risky for people with active cardiovascular disease or risk factors for it.”
What are proven to delay cognitive decline and Alzheimer’s, according to Dr. Marshall, include dietary and lifestyle changes – specifically the Mediterranean diet and exercise.
“My strongest recommendations are a Mediterranean-style diet and regular physical exercise,” he says. “There’s good evidence from multiple studies showing that these lifestyle modifications can prevent cognitive decline and dementia and also slow down existing cognitive decline.”
These two factors have been proven to reduce memory and cognitive decline without question. The evidence comes from numerous studies and reviews from eminent researchers around the world.
Studies link diet and cognition
For example, a study from Australia’s Edith Cowan University of nearly 1,000 people – including some with mild cognitive decline and Alzheimer’s – found that those who had diets closest to a Mediterranean Diet had the least incidence of cognitive decline and Alzheimer’s disease. Many other studies have confirmed these results over the past few years.
So what about the supplements mentioned above? Why are have these been given so much attention if they aren’t proven to prevent or delay Alzheimer’s?
Because those nutrients have been proven, in one way or another, to benefit nerve function and brain cell function. The leap, however, has been to prove that when taken as supplements, these isolated nutrients will reduce cognitive decline or prevent Alzheimer’s disease.
As to whether the research has been focused enough to establish that these supplements will definitely not help reduce cognitive decline is largely unanswered, primarily because of a lack of funding and incentive – noting that naturally occurring nutrients cannot be patented. Ginkgo and vitamin E are among the few given much funding focus.
Why does the Med diet help?
The question also arises is what are the factors of the Mediterranean diet and why does this diet help reduce cognitive decline? As stated recently by researchers from the University of Malta – the Med Diet “is rich in the antioxidants Vitamins C and E, polyunsaturated fatty acids and polyphenolic compounds.”
As we explore the relationship between many of the supplements tested and these nutrient-rich foods, we can easily see a trend. Those supplements tested, such as B vitamins, vitamin C, vitamin E, Co-Q10 and others have been isolated from nature and in sterile laboratory environments. Some, such as vitamin E, have been completely synthetic.
What do these elements have in common with the Mediterranean diet? Yes, the Med Diet certainly does contain many of these nutrients. But the Med Diet, as pointed out by the University of Malta scientists – contains numerous nutrients that synergize with each other. And because the Med Diet is rich in plant-based foods, the Diet contains polyphenols.
These polyphenols are plant components that include flavonoids, proanthrocyanidins, sterols and many other types of special compounds. These compounds work synergistically within plant-based foods to provide a host of benefits, which include brain cell health, artery health, heart health, liver and kidney health and many others. The combination of these plant-based foods provide the ultimate in cognitive decline prevention, because along with other benefits they reduce damage produced by free radicals – which are ultimately at the core of cognitive decline according to most research.
The bottom line is that nature works in synergy, just as the body does. The brain does not sit in a laboratory jar isolated from the rest of the body. The brain operates as part of the rest of the whole body. The health of the rest of that body – including the arteries, heart, liver, kidneys, bloodstream and so on – directly affects the health of our brain cells.
A primarily plant-based diet and regular exercise are the key elements in keeping the whole body healthy. This is proven not only in cognitive research, but in cancer research, heart disease research, liver and kidney research and elsewhere. Turns out, those plant-based foods the Western diet relegates to a small portion at the edge of the plate are the very medicines our body needs to keep itself healthy.
Cognitive link to heart disease
Both nut consumption and the Med diet has been associated with cardiovascular health and mortality in other research.
A study from Harvard that calculated the results of 18 studies that included over 83,000 patients with various metabolic syndrome disorders found in their pooled analysis that nut consumption reduced the risk of ischemic heart disease by 36%, cardiovascular disease by 30%, strokes by 9%, and reduced death from all causes by 15%.
The relationship between the Med diet and cognition was confirmed in a study from the UK’s University of Exeter Medical School. This study reviewed 12 studies, and the researchers concluded that higher adherence to the Med diet was associated with less cognitive decline, better cognitive function and reduced risk of Alzheimer’s disease. They concluded:
“Published studies suggest that greater adherence to Mediterranean diet is associated with slower cognitive decline and lower risk of developing Alzheimer disease.”
Samieri C, Okereke OI, E Devore E, Grodstein F. Long-term adherence to the Mediterranean diet is associated with overall cognitive status, but not cognitive decline, in women. J Nutr. 2013 Apr;143(4):493-9. doi: 10.3945/jn.112.169896.
O’Brien J, Okereke O, Devore E, Rosner B, Breteler M, Grodstein F. Long-term intake of nuts in relation to cognitive function in older women. J Nutr Health Aging. 2014;18(5):496-502. doi: 10.1007/s12603-014-0014-6.
Luo C, Zhang Y, Ding Y, Shan Z, Chen S, Yu M, Hu FB, Liu L. Nut consumption and risk of type 2 diabetes, cardiovascular disease, and all-cause mortality: a systematic review and meta-analysis. Am J Clin Nutr. 2014 May 21. pii: ajcn.076109.
Martínez-Lapiscina EH, Clavero P, Toledo E, Estruch R, Salas-Salvadó J, San Julián B, Sanchez-Tainta A, Ros E, Valls-Pedret C, Martinez-Gonzalez MÁ. Mediterranean diet improves cognition: the PREDIMED-NAVARRA randomised trial. J Neurol Neurosurg Psychiatry. 2013 Dec;84(12):1318-25. doi: 10.1136/jnnp-2012-304792.
Martínez-Lapiscina EH, Clavero P, Toledo E, San Julián B, Sanchez-Tainta A, Corella D, Lamuela-Raventós RM, Martínez JA, Martínez-Gonzalez MÁ. Virgin olive oil supplementation and long-term cognition: the PREDIMED-NAVARRA randomized, trial. J Nutr Health Aging. 2013;17(6):544-52. doi: 10.1007/s12603-013-0027-6.
Berr C, Portet F, Carriere I, Akbaraly TN, Feart C, Gourlet V, Combe N, Barberger-Gateau P, Ritchie K. Olive oil and cognition: results from the three-city study. Dement Geriatr Cogn Disord. 2009;28(4):357-64. doi: 10.1159/000253483.
Féart C, Pérès K, Samieri C, Letenneur L, Dartigues JF, Barberger-Gateau P. Adherence to a Mediterranean diet and onset of disability in older persons. Eur J Epidemiol. 2011 Sep;26(9):747-56. doi: 10.1007/s10654-011-9611-4.
Gu Y, Scarmeas N. Dietary patterns in Alzheimer’s disease and cognitive aging. Curr Alzheimer Res. 2011 Aug;8(5):510-9.
Solfrizzi V, Frisardi V, Seripa D, Logroscino G, Imbimbo BP, D’Onofrio G, Addante F, Sancarlo D, Cascavilla L, Pilotto A, Panza F. Mediterranean diet in predementia and dementia syndromes. Curr Alzheimer Res. 2011 Aug;8(5):520-42.
Solfrizzi V, Panza F, Frisardi V, Seripa D, Logroscino G, Imbimbo BP, Pilotto A. Diet and Alzheimer’s disease risk factors or prevention: the current evidence. Expert Rev Neurother. 2011 May;11(5):677-708.
Devanand D, Lee J, Luchsinger J, Manly J, Marder K, Mayeux R, Scarmeas N, Schupf N, Stern Y. Lessons from Epidemiologic Research about Risk Factors, Modifiers, and Progression of Late Onset Alzheimer’s Disease in New York City at Columbia University Medical Center. J Alzheimers Dis. 2012 Jul 24.
Wyka J. Nutritional factors in prevention of Alzheimer’s disease. Rocz Panstw Zakl Hig. 2012;63(2):135-40.
Gardener S, Gu Y, Rainey-Smith SR, Keogh JB, Clifton PM, Mathieson SL, Taddei K, Mondal A, Ward VK, Scarmeas N, Barnes M, Ellis KA, Head R, Masters CL, Ames D, Macaulay SL, Rowe CC, Szoeke C, Martins RN; AIBL Research Group. Adherence to a Mediterranean diet and Alzheimer’s disease risk in an Australian population. Transl Psychiatry. 2012 Oct 2;2:e164.
Vassallo N, Scerri C. Mediterranean Diet and Dementia of the Alzheimer Type. Curr Aging Sci. 2012 Sep 27.