New research is casting some doubt on low fat diets in at least one specialized health area. A new study in the journal Neurology that was funded by the National Institute on Aging and the Department of Veterans Affairs found that a diet high in animal fat and protein may protect against the onset of dementia in people who have suffered a stroke. 

As a subset of the original Honolulu Heart Study that began in 1965, the Honolulu-Asia Aging Study began in 1991 to study dementia Researchers compared pre-study dietary preferences of 68 study participants who later developed dementia as a result of a stroke with the preferences of 106 participants who had had a stroke but were not suffering from dementia, and 3,335 other participants who had had neither a stroke nor dementia.

The researchers found that those who preferred a Western diet that is higher in animal fat and protein and lower in complex carbohydrates than a traditional Asian diet were 57 percent less likely to develop dementia following a stroke. A lower incidence of stroke-related dementia was also found in people who took vitamin E supplements.

Stroke-related dementia is the second-leading cause of dementia in the U.S. after Alzheimer's disease. Between one and two million people in the United States suffer from stroke-related or vascular dementia with its deterioration of emotional and cognitive abilities and loss of memory, language, reasoning and personality skills. Not surprisingly, the highest prevalence of dementia was found in the oldest study participants. The study also found that controlling hypertension and diabetes could help prevent strokes and vascular dementia.

Why would there be a protective effect from animal fat and protein in dementia versus its harmful effects in generating more heart disease and cancer? There are several possibilities. One may be due to the structural differences between the saturated fats found in animal products and the unsaturated fats found in fish, vegetables and seeds. 

Saturated fats are linear, meaning their structure is straight. Although this has been shown to have damaging effects, such as less flexible blood vessels and cell walls and higher cholesterol levels, it may also provide greater stability to blood vessel walls following a damaging event like a stoke. 

Saturated fat is also less likely to undergo oxidation which can trigger secondary damage than fats with double bonds and a more complex structure as is found in unsaturated fats. Strokes shut off the flow of blood and oxygen to an area of the brain. When normal repair processes begin and blood flow reopens, oxygen returns to the oxygen-starved areas of the brain and the return of oxygen triggers a marked increase in damaging oxidation. Saturated fats are not as prone to damage in this unique setting. The study's finding for a protective role for the antioxidant vitamin E, found primarily within fat-containing structures, supports this theory.

To balance this, people who live in the Orient and eat relatively little animal products have a lower risk of cognitive decline. Basically this study says that if you want to prevent a stoke, stay away from animal fats, but if you are planning to have one, start eating your red meat and taking your vitamin E. (Note: vitamin E is highly recommended no matter what your plans.) 

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