Diets high in saturated fat and high glycemic carbohydrates increase amyloid.

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A study published in JAMA Neurology suggest that what you eat can directly affect how much amyloid, the toxic protein linked to the development of Alzheimer’s disease, is cleared from your brain.

Researchers from the University Of Washington School Of Medicine in Seattle, Washington found that diets high in saturated fat and high glycemic carbohydrates increase amyloid, while diets low in these foods decrease it. The study researchers believe their findings have implications not only for Alzheimer’s disease treatment, but also for preventing Alzheimer’s in those who are at high risk due to genetics or lifestyle-related medical conditions like insulin resistance.

Toxic amyloid proteins must get cleared from the brain for successful Alzheimer’s disease treatment

One of the main reasons Alzheimer’s develops is that amyloid stops getting efficiently cleared from the brain. In order for amyloid to be cleared, it must attach itself to apolipoprotein E (ApoE). If it remains free instead of attaching to ApoE, it starts to build up and form toxic clusters. The study showed that diet affects levels of this free amyloid, with a high saturated fat, high sugar diet increasing levels and a low saturated fat, low sugar diet reducing levels.

How diet affects Alzheimer’s disease treatment: study details

The study included 27 subjects with no signs of Alzheimer’s or cognitive impairment and 20 with mild cognitive impairment. The subjects were randomly assigned to 4 weeks on a high-fat diet with a high glycemic index or a low-fat diet with a low glycemic index. The diets had the same number of calories and were based on the calculated caloric needs of individual participants, so that each maintained his or her body weight.

In the high-fat diet, 45% of calories came from from fat (25% from saturated fat) and the average glycemic index was greater than 70. Cheeseburgers, soda, and French fries might be included in a typical meal for this group. In the low-fat diet, only 25% of calories came from total fat (less than 7% from saturated fat) and the average glycemic index was less than 55. A typical meal in this group might include fish, brown rice, and steamed vegetables.

Using cerebrospinal fluid samples, researchers measured the amount of dangerous free amyloid as well as the amount of amyloid attached to ApoE for clearance. They also tested the participants to see who carried the gene associated with increased Alzheimer’s disease risk, known as ApoE4.

Study’s findings have implications for Alzheimer’s disease treatment and dementia prevention

Overall, they found that concentrations of free amyloid, which is the type that tends to accumulate in the brain and cause Alzheimer’s, was affected by diet. In general, the amount of free amyloid was increased in those eating the high fat/high glycemic index diet and decreased in those on the low fat/low glycemic index diet.

Previous research linked high fat and high sugar to dementia

The researchers concluded that diets can increase or decrease Alzheimer’s risk and may affect Alzheimer’s disease treatment by increasing or decreasing levels of the dangerous free amyloid in the brain. While diets high in levels of saturated fat and simple sugars (high glycemic carbohydrates) have been implicated in causing Alzheimer’s disease for some time, this is the first study to show that these foods increase brain levels of free amyloid.

To learn more about incorporating diet changes and other natural remedies for dementia and Alzheimer’s disease treatment, view our resources here.

[1] JAMA Neurol. 2013;():1-9.

This post originally appeared in 2013 and has been updated.