Up to half of Alzheimer’s cases may be attributable to just seven risk factors shown in my video, Preventing Alzheimer’s with Lifestyle Changes, which include diabetes, high blood pressure, obesity, exercise, smoking, depression, and mental exercise; and that’s not including diet because there are so many dietary factors that researchers couldn’t fit them into their model. But, they acknowledged that diet might be another important modifiable risk factor for Alzheimer’s disease. In particular, there is growing evidence that dietary patterns, such as the Mediterranean diet, are associated with lower Alzheimer’s risk, as well as slower cognitive decline, but which constituents of the Mediterranean diet are responsible?
The traditional Mediterranean diet is a diet high in intake of vegetables, beans, fruit, and nuts, and low in meat and dairy. When researchers tried to tease out the protective components, fish consumption showed no benefit, neither did moderate alcohol consumption. The two critical pieces appeared to be vegetable consumption, and the ratio between unsaturated fats and saturated fats, essentially plant fats to animal fats.
In studies across 11 countries, fat consumption appeared to be most closely correlated with the prevalence of Alzheimer’s disease, with the lowest fat intake and Alzheimer’s rates in China to the highest fat intake and Alzheimer’s rates in the United States. But this is grouping all fats together.
Harvard researchers examined the relationships of the major fat types to cognitive change over four years among 6,000 healthy older women, and found that higher saturated fat intake was associated with a poorer trajectory of cognition and memory. Women with the highest saturated fat intake had 60 to 70% greater odds of worse change on brain function. The magnitude of cognitive change associated with saturated fat consumption was equivalent to about six years of aging, meaning women with the lowest saturated fat intake had the brain function of women six years younger.
What if one already has Alzheimer’s, though? Previously, a group of Columbia University researchers reported that eating a Mediterranean-style diet was related to lower risk for Alzheimer’s disease, but whether a Mediterranean diet—or any diet for that matter—is associated with the subsequent course of the disease and outcomes had not been investigated, until now.
In a study highlighted in my video, Preventing Alzheimer’s Disease with Diet, researchers found that adherence to the Mediterranean diet may affect not only risk for Alzheimer’s disease, but also subsequent disease course, as higher adherence to the Mediterranean diet was associated with lower mortality. And the more they adhered to the healthier diet, the longer they lived. Within five years, only 20% of those with high adherence died, with twice as many deaths in the intermediate adherence group. In the low adherence group, within five years, more than half were dead, and by ten years, 90% were gone. By the end of the study, the only people still alive were those with higher adherence to the healthier diet.
For more on the Mediterranean diet, check out:
- Why Was Heart Disease Rare in the Mediterranean?
- The Mediterranean Diet or a Whole Food Plant-Based Diet?
- PREDIMED: Does Eating Nuts Prevent Strokes?
- Which Parts of the Mediterranean Diet Extended Life?
- Do Flexitarians Live Longer?
- Improving on the Mediterranean Diet
I do have a bunch on dietary factors in cognitive decline, though:
- Constructing a Cognitive Portfolio
- Reversing Cognitive Decline
- Improving Memory Through Diet
- Dietary Theory of Alzheimers
- How to Slow Brain Aging by Two Years
Michael Greger, M.D.
PS: If you haven’t yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death, More Than an Apple a Day, From Table to Able, and Food as Medicine.