Researchers at Brigham and Women’s Hospital in Boston, reporting in Annals of Neurology, identified the ratio of unsaturated fats to saturated fats as a key factor in Alzheimer’s. Women in their 6,000 person study who ate the most saturated fats from foods like red meat, French fries, cream and butter performed worst on thinking and memory tests.
Indeed women with the highest saturated fat intake had a 60 to 70% greater risk of deteriorating brain function. The extent of cognitive change linked to saturated fat consumption was equivalent to about six years of ageing! Conversely those women with the lowest saturated fat intake had the brain function of women six years younger.
But why? There appear to be three mechanisms at work.
1. Saturated fats raise LDL (bad) cholesterol
First, we know that saturated fat can raise blood levels of low-density lipoprotein (LDL) the unhealthy form of cholesterol. Diets high in cholesterol and fat appear to speed up the formation of beta-amyloid plaques in the brain. These plaques are the sticky protein clusters linked to the damage that occurs in the brains of people with Alzheimer’s.
2. Cholesterol plaques damage the brain
Secondly the build-up of cholesterol plaques can damage brain tissue, either through small blockages that cause damage to blood vessels or even silent mini-strokes. Either way, brain cells are deprived of the oxygen-rich blood they need to function normally, which can cause thinking and memory problems.
3. Fats and LDL cholesterol turn on APOE4 gene
Thirdly, higher levels of saturated fat and cholesterol may cause a gene to be expressed called apolipoprotein E, or APOE. This gene is associated with the amount of cholesterol in your blood, and people with a variation of this gene, called APOE4 are at significantly greater risk for Alzheimer’s disease.
Dr Gad Marshall, assistant professor of neurology at Harvard Medical School says:
“About 65% of individuals who wind up with dementia due to Alzheimer’s disease in their 60s and 70s have that (APOE4) gene.”
Prefer vegetable-based non-processed fats
In studies across 11 countries, fat consumption (type and quantity) appears to be closely correlated with the prevalence of Alzheimer’s disease.
The lowest fat intake and Alzheimer’s rates are in China, where the diet and fat source is largely vegetable based.
The highest fat intake and Alzheimer’s rates are in the United States with far higher dietary animal and saturated fat sources.
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Dr Paul Clayton’s best-selling book Health Defence is available from most good bookstores. See the website www.healthdefence.com for excerpts and links to buy direct from the publisher.
Okereke OI, Rosner BA, Kim DH, Kang JH, Cook NR, Manson JE, Buring JE, Willett WC, Grodstein F. Dietary fat types and 4-year cognitive change in community-dwelling older women. Annals of Neurology, 17 May 2012