Can a healthy diet help you remember the names of everyone at your 100th birthday party?
The twentieth century has seen a drastic increase in longevity. In Canada, seniors are our most rapidly growing population and it is estimated that by 2026 20% of Canadians will be aged 65 years or older (1). People are also living much, much longer and Statistics Canada reports that the number of centenarians increased by 25.7% between 2006 and 2011 . Our changing demographic creates a variety of challenges that will require social, economic and health care restructuring. One of the primary health concerns for the aging population is not physical health but rather mental health.
Can a healthy diet throughout the lifespan reduce the cognitive (mental) decline many individuals experience later in life?
Currently more than 500,000 Canadians live with Alzheimer’s disease or dementia and that number is expected to double by 2038. Presently, there are limited treatments and strategies for slowing the progression of cognitive decline, making a strong case for preventative measures that can be taken early on in life. The nutritional investigation into aging and cognitive function has taken two different approaches.
The first is to look at the effects of individual nutrients. There is limited (and sometimes conflicting) evidence to suggest that the B-vitamins, polyunsaturated fatty acids (PUFA) and a variety of antioxidants help prevent or postpone cognitive decline (2, 3). Individual nutrients that may have a role in preventing cognitive decline were discussed at the 2012 Canadian Nutrition Society conference and you can see our summary here.
The second approach is to look at overall diet quality on health outcomes. With this in mind, there is research to suggest that following the Mediterranean diet could reduce the risk of cognitive decline or dementia (4). A recent study by Kesse-Guyot et al. (5) looked at overall dietary patterns in midlife and cognitive performance after a 13-year follow up. They tracked the dietary patterns of 3,054 French participants with an average age of 52 years at baseline and 65 years at the study completion. Dietary patterns were established based on a factor analysis – dietary habits exhibiting the strongest associations (r > 0.25) to specific ways of eating were combined to label two diet classifications:
- A “healthy pattern” was associated with high intake of fruit, whole grains, fresh dairy products, vegetables, breakfast cereal, tea, vegetable fat, nuts and fish and was low in meat, poultry, refined grains, animal fat and processed meat.
- A “traditional pattern” that was linked with more vegetables, vegetable fat, meat and poultry and with less confectionary, cakes pastries, croissants, pizza, soft drinks, milk and potatoes.
They found that following a “healthy” dietary pattern in middle life could prevent overall cognitive decline, especially verbal memory. However, there is a caveat here; the effects depended on overall energy as well as the dietary pattern and it was those in the “healthy pattern” who consumed fewer than 2490 kcal/d for males and 1810 kcal/d for females that benefited. They suggest this is because those who consumed more calories had more processed meats, animal fat, salty snacks, cheese, sweetening products and alcohol. It appears that both diet quantity and quality are important in cognition.
It should be noted that the study is limited in that there was no thorough cognitive evaluation at baseline, so they were not able to adjust for baseline differences or focus on cognitive decline. Nevertheless, they were able to used quartiles (top 25%, etc.) of the 13-year dietary patterns, to make the connections between diet and cognitive function. Further long-term studies that track cognitive performance over time are needed but this research provides some stimulating preliminary data.
No Baloney’s advice? Eating habits throughout your lifespan can clearly impact your quality of life as you age. This has been shown time and again with cancer, diabetes, obesity and cardiovascular disease, and now with Alzheimer’s and dementia. You need to load up on those veggies, fruits and whole grains! Also minimize processed foods as much as possible and, to a lesser degree, reduce intake of red meat and poultry – try to have at least one meatless meal per week by including more beans and legumes. Overall caloric intake is also very important. It is not sufficient to eat more healthy foods, we also need to minimize the unhealthy whenever possible.
To quote Michael Pollan: “Eat food. Not too much. Mostly plants.”
- Health Canada, Division of Aging and Seniors. (2002) Canada’s Aging Population. Retrieved June 8th, 2012 from http://publications.gc.ca/collections/Collection/H39-608-2002E.pdf
- Sofrizzi V, et al. Diet and Alzheimer’s disease risk factors or prevention: the current evidence. Exper Rev Neurother 2011; 11:677-708.
- Dangour AD, Whitehouse PJ, Rafferty K, Mitchell SA, Smith L, Vellas B. B-vitamins and fatty acids in the prevention and treatment of Alzheimer’s disease and dementia: a systematic review. J Alzheimers Dis 2010: 22:205-24.
- Feart C, Samieri C, Barberger-Gateau P. Mediterranean diet and cognitive function in older adults. Curr Opin Clin Metab Care 2010; 13:14-8.
- Kesse-Guyot E, et al. A healthy dietary pattern at midlife is associated with subsequent cognitive performance. J Nutr 2012; 143:909-915.