Elderly people who get relatively low amounts of the B vitamin niacin in their diets may be more likely to develop Alzheimer's within the next few years than others, according to preliminary research from Rush-Presbyterian-St. Luke's Medical Center in Chicago. This finding needs to be confirmed by additional studies before the B vitamin can be linked to Alzheimer's.
In the study, researchers recorded how much niacin a group of 815 dementia-free people at least 65 years old ate in their diets, and tracked who developed Alzheimer's over the next 4 years. Foods that contain relatively high levels of niacin include meat such as chicken, nuts, legumes and enriched grains and cereals. The current recommended daily allowance (RDA) is 16 milligrams (mg) per day for men and 14 mg per day for women.
The investigators divided people into five groups based on their niacin intake. They discovered that people who ate the most niacin--of whom half consumed more than 22 mg each day--were 79% less likely to develop Alzheimer's than were those who ate the least. Half of the lowest consumers of the B vitamin took in less than 13 milligrams per day.
Morris explained that the benefits of niacin appeared to kick in as soon as people increased their intake only slightly, for the second-lowest niacin consumers were also 70% less likely to develop Alzheimer's during the study period than those who ate the least.
But why levels only slightly below the niacin RDA were linked to an increased Alzheimer's risk remains unclear. People who eat relatively little of the nutrient may develop a condition marked by confusion and psychosis, which niacin supplements can correct. Animal studies also suggest that low levels of niacin in the body could lead to brain cell damage.
Previous reports have shown that some vitamin supplements contain much higher levels of niacin than the RDA, and too much niacin may cause flushing, itching and other symptoms. As a result, the researchers recommended that people who want to take in more niacin focus on getting it from foods.
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