This is the first post in a series on complementary and alternative treatments of Alzheimer’s disease and other kinds of dementia. My posts will focus on complementary and alternative treatments of Alzheimer’s disease because it is the most common type of dementia accounting for two thirds of all cases of dementia in the U.S. (Plassman 2011). This post is about the relationship between diet and Alzheimer’s risk. Future posts will review evidence for herbals, other natural supplements, and a promising emerging treatments of dementia.
Diets low in saturated fat and total calories and moderate alcohol consumption reduce the risk of developing Alzheimer’s disease
Diet may be the most important preventable risk factor in Alzheimer’s disease. Foods that increase the risk of Alzheimer’s include red meat, foods with high sugar content, and high-fat dairy products. Individuals who consume a high-fat, high-calorie diet are at significantly greater risk of developing Alzheimer’s dementia compared with individuals who have moderate fat intake and restrict total calories. High red meat consumption also impacts health in general by increasing the risk of several types of cancer, diabetes, obesity, kidney disease and stroke.
A meta-analysis of findings from 18 community-wide studies concluded that the risk of Alzheimer’s disease increased linearly at a rate of 0.3% with every 100-calorie increase in daily intake (Grant, 1997). Average daily fat consumption was highly correlated with increased risk of developing dementia. The same meta-analysis showed that fish consumption was the only specific dietary factor associated with a measurable reduction in the risk of developing Alzheimer’s disease.
The relationship between diet and Alzheimer’s risk is complex and probably involves oxidative stress caused by red meat, atherosclerosis caused by high cholesterol, and formation of damaging molecules caused by dysregulation of insulin secretion. High caloric intake and high fat intake promote formation of damaging free radicals that cause diffuse neuropathological changes in the brain, eventually manifesting as Alzheimer’s disease.
Established preventive benefits of the Mediterranean diet
Foods known to reduce the risk of developing Alzheimer’s disease include vegetables, grains, fish and fruits. Individuals who consume a traditional Mediterranean diet are at roughly one half the risk of developing Alzheimer’s disease compared to individuals who consumer a high-fat high-calorie diet, and individuals in countries with very low meat consumption such as Japan, are at even lower risk of developing Alzheimer’s disease (Grant 2016). Fish are an important source of omega-3 fatty acids, for which there is emerging evidence of beneficial and possibly preventive effects in dementia and less severe forms of cognitive impairment.
Heavy chronic drinking increases dementia risk while moderate drinking reduces risk
Heavy chronic alcohol abuse increases the risk of vascular dementia caused by stroke however moderate alcohol consumption (2–4 glasses of wine per day) is associated with reduced risk of Alzheimer’s disease (Orgogozo et al., 1997; Letenneur 2004).
Dietary changes are an important preventive strategy
Recent research findings show that changes in the brain associated with increased risk of developing Alzheimer’s disease start many years before the onset of cognitive decline. Thus proactive dietary changes represent an important strategy for delaying or preventing Alzheimer’s disease (Rodriguez-Vieitez 2016).
Take home lessons
Red meat and high calorie foods significantly increase the risk of developing Alzheimer’s disease, many kinds of cancer, diabetes and other serious medical problems. A Mediterranean diet and moderate alcohol consumption reduce Alzheimer’s risk. In response to the growing body of evidence for the central role of diet in Alzheimer’s disease risk, the Physicians Committee for Responsible Medicine has recommended minimizing intake of saturated fats and trans fats and replacing meats and dairy products with fresh vegetables, fruits, and whole grains (Barnard 2014). Finally, widespread red meat consumption is correlated with increased global warming because of the relationship between large scale cattle production and methane being released into the atmosphere, thus reducing meat consumption may be an important factor in slowing the rate of global warming.