By Craig Weatherby
A major population study suggests that the so-called “Mediterranean” diet may help preserve memory and thinking in healthy people.
Conversely, no benefit was seen from diets lower in plant foods and higher in dairy and meats … such as the standard American diet.
However, don’t trust headlines saying the study damns dairy and meats.
Most Americans who down lots of meat and dairy (e.g., cheeseburgers and pepperoni pizza) also eat lots of brain-fogging refined carbs (sugars and starches) and lead relatively sedentary lives … see “Carbs Fog Aging Brains” and “Fast Food Diet May Raise Alzheimer’s Risk”.
The Mediterranean diet is generally defined as one that rests heavily on vegetables, fruits, beans, nuts, extra virgin olive oil, and fish … plus small amounts of cheese, yogurt, bread, pasta, rice, poultry, and meat.
Compared with the standard American diet, the Mediterranean diet is rich in beneficial, gene-influencing “antioxidants”, and has a very different fat profile:
Lower in saturated fats from meats and dairy.
Higher in omega-3 fatty acids from beans, greens, and fish.
Higher in monounsaturated fats from antioxidant-rich extra virgin olive oil.
Lower in omega-6 fatty acids from common oils other than olive, macadamia, hi-oleic sunflower, and canola (e.g., omega-6-rich corn, soy, cottonseed, safflower, and sunflower oils).
Early diet-health study damned dairy and meat ... deceptively
The first hints of health benefits gained by eating a so-called “Mediterranean” diet emerged in the 1960’s.
These signs came from the famed Seven Countries Study, and they've been confirmed since then, extensively and convincingly.
However, other key “findings” from that study have since been proven misleading, because the data was deplorably cherry-picked to fit unwarranted presumptions about dietary fats and cholesterol.
Sadly, some of those data distortions led a prominent Congressional panel to conclude that dietary cholesterol and saturated fats cause most heart disease.
That erroneous conclusion helped lead to 40 years of misguided heart-health policy, aimed at replacing animal fats (butter, lard) with polyunsaturated vegetable fats.
Ironically, America’s sharp turn toward cheap vegetable oils (largely from packaged and prepared foods) produced the extreme overload of omega-6 fatty acids virtually proven to harm heart, brain, and metabolic health … and fuels cancer growth.
Although saturated animal fats now appear innocent of causing heart disease, recent research raises concerns about the long term brain-health effects of diets high in cholesterol and saturated animal fats from dairy and meats.
For example, the Mayo Clinic Study of Aging found that the risk of “mild cognitive impairment (MCI) – a predictor of later dementia – was lower among those with lowest intake of saturated fats and highest intakes of unsaturated fats from fish and plant foods.
And the lowest MCI risk was seen among those with the highest omega-3 intakes (see “Fat Choices Linked to Brain Aging”). Findings like those have been bolstered by subsequent population studies … such as the ones we reported in “Brain Aging Delayed by Mediterranean Diet”, “Brain Benefits from Olive Oil?”, and others covered in the Foods & Brain Health section of our news archive.
Now, a joint U.S.-European team reports more evidence that the standard American diet may promote or accelerate memory loss.
Mediterranean diet linked to preserving mind and memory
The new analysis came from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, housed at the University of Alabama at Birmingham (UAB).
The REGARDS researchers enrolled 30,239 people ages 45 and older between January 2003 and October 2007, and continue to follow their health status, looking for any changes (Tsivgoulis G et al. 2013).
In the largest such study to date, the UAB team questioned 17,478 African-Americans and Caucasians – with an average age of 64 years – about their diet habits.
The scientists then reviewed the volunteers’ answers to see how closely their reported diets adhered to a Mediterranean-style model.
Participants also took standard tests of memory and cognitive (thinking) capacity, both at the outset, and after follow-up periods varying from four to almost six years.
After adjusting the results to account for the impacts of known risk factors for MCI, the analysis indicated that those who followed a Mediterranean-style diet most closely were 19 percent less likely to develop thinking and memory declines within the study period.
Unfortunately, participants with diabetes who followed a Mediterranean-style diet showed no protection from brain decline ... at least not within the study period.
Presumably, the multiple metabolic problems driven and sustained by diabetes overcame any benefit they might otherwise have gained from following the diet.
It was good to see that there was no significant difference between African-Americans and Caucasians … both ethnic groups gained or lost brain power the same extent depending on diet.
Lead author Georgios Tsivgoulis, M.D., a neurologist with UAB and the University of Athens – expressed the value of their findings (UAB 2013):
“Since there are no definitive treatments for most dementing illnesses, modifiable activities, such as diet, that may delay the onset of symptoms of dementia, are very important.”
Of course, as Tsivgoulis added, “… [diet] is only one of several important lifestyle activities that might play a role in late-life mental functioning. Exercise, avoiding obesity, not smoking cigarettes, and taking medications for conditions like diabetes and hypertension are also important.”
As an epidemiological study, this one cannot prove a cause-effect relationship between diet and health … only a statistical correlation. That said, when the results of epidemiological studies looking for the same links match up – and fit well with a substantial body of lab and clinical evidence – it seems wise to act.
Féart C, Samieri C, Rondeau V, Amieva H, Portet F, Dartigues JF, Scarmeas N, Barberger-Gateau P. Adherence to a Mediterranean diet, cognitive decline, and risk of dementia. JAMA. 2009 Aug 12;302(6):638-48. doi: 10.1001/jama.2009.1146. Erratum in: JAMA. 2009 Dec 9;302(22):2436.
Tsivgoulis G, Judd S, Letter AJ, Alexandrov AV, Howard G, Nahab F, Unverzagt FW, Moy C, Howard VJ, Kissela B, Wadley VG Adherence to a Mediterranean diet and risk of incident cognitive impairment. Neurology. 2013 Apr 30;80(18):1684-1692.
University of Alabama at Birmingham (UAB). Mediterranean diet linked to preserving memory. Accessed May, 2013 at http://www.uab.edu/news/latest/item/3412-mediterranean-diet-linked-to-preserving-memory