Vitamin D Foods May Reduce Alzheimer's Risk, But Which Are Best?

2012-04-25 06:22
Fish is a good source of vitamin D

A new study suggests that eating more foods rich in vitamin D may reduce the risk of developing Alzheimer’s disease. This study joins others that point to dietary steps people can take to help ward off this devastating disease.

Can you eat your way past Alzheimer’s disease?

The aging population faces many health issues, and one of the most pressing is Alzheimer’s disease. While 5.4 million Americans currently have Alzheimer’s disease, it has been estimated this number will double by 2050. Worldwide, the number is expected to reach 106 million by 2050.

As the exact causes of Alzheimer’s disease are still unknown and no treatment has been found to be effective, people are looking for ways to help prevent or at least slow the disease. Dietary factors, including avoiding high cholesterol foods and following a Mediterranean diet and exercise, have often been named as being potential preventive measures.

In a new study from France, researchers evaluated 498 older women (average age, 79.8 years) who did not take vitamin D supplements. Investigators analyzed the women’s dietary habits regarding vitamin D intake and followed the volunteers for seven years.

The women who had the lowest intake of vitamin D (50 micrograms [mcg] per week) had a greater risk of developing Alzheimer’s disease when compared with women who had an intake of 59 mcg per week. Overall, women with the highest average intake of vitamin D from their diet had the lowest risk of Alzheimer’s disease.

The authors noted several possible explanations for this finding. One was related to vitamin D’s protective effect on the hippocampus (a center of memory in the brain) as seen in rodent studies, while another possibility was the vitamin’s influence on the production and elimination of beta-amyloid proteins. These proteins are believed to play a key role in the development of Alzheimer’s disease.

Best vitamin D foods
Another possibility is related to the presence of vitamin D in fish, which is a rich source of the nutrient. The authors noted that “there is reasonably good evidence that eating fish reduces the risk of dementia including Alzheimer’s,” and that “this effect is generally attributed to the omega-3 polyunsaturated fatty acids even if data are conflicting.”

A study presented at the Radiological Society of North America annual meeting in November 2011 noted that at least one serving of baked or broiled fish per week can help preserve gray matter in the brain. One of the study’s authors, Cyrus Raji, MD, PhD, from the University of Pittsburgh Medical Center, noted that his study was the first “to establish a direct relationship between fish consumption, brain structure and Alzheimer’s risk.”

Many types of fish have the distinction of being excellent sources of both omega-3 fatty acids and vitamin D. But there are other foods that are good sources of vitamin D as well. Here's what you should know:

  • Fish that are excellent sources of vitamin D include salmon (very good), tuna, herring, sardines, halibut, catfish, and mackerel
  • Fortified cow's milk and soy beverages are also recommended
  • Fortified orange juice can provide just as much vitamin D as fortified milk and soy beverages--check the labels
  • Fortified cereals are also good choices. If you eat fortified cereals with fortified milk or soy beverages, plus drink fortified orange juice, you can get a significant amount of vitamin D from just one meal

The University of Pittsburgh study pointed out, however, that fish should be baked or broiled, not fried, to reap the benefits.

Although the best way to get adequate amounts of vitamin D is via regular but limited exposure to sunlight (approximately 15-20 minutes of unprotected exposure to sunlight 3 to 4 times a week), many people do not reach this goal because of geography or lack of access to sunlight during the day for work, health, or other reasons.

That means people can choose to get their vitamin D through foods (of which few are good sources of the nutrient) and/or via supplements. This latest study found that vitamin D intake from food could help reduce the risk of Alzheimer’s disease, which supports previous research suggesting vitamin D has a role in preventing the disease.

SOURCES:
Alzheimer’s Association
Annweiler C et al. Higher vitamin D dietary intake is associated with lower risk of Alzheimer’s disease: a 7-year follow-up. Journal of Gerontology: Medical Science 2012; doi:10.1093/gerona/gls107
Hebert LE et al. Annual incidence of Alzheimer disease in the United States projected to the years 2000 through 2050. Alzheimer Disease & Associated Disorders 2001; 15(4): 169-73

Image: Wikimedia Commons

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