The statistics say that one in three older Americans have Alzheimer’s disease or some other form of dementia when they die. There is no cure for these cognitive problems yet, but researchers are looking for treatments that can alter the course of the disease or improve the quality of life for affected individuals.
It may be that simply avoiding a vitamin deficiency could reduce the odds of developing memory problems in old age.
A study just published by the American Academy of Neurology suggests that a lack of vitamin D may double the risk of developing Alzheimer’s disease or dementia.
“We expected to find an association between low Vitamin D levels and the risk of dementia and Alzheimer's disease, but the results were surprising—we actually found that the association was twice as strong as we anticipated,” one of the study authors, David J. Llewellyn, said in a statement.
Vitamin D is naturally present in very few foods. Fatty fish (salmon, tuna, and mackerel) and fish liver oils are the best sources. Cheese, beef liver, and egg yolks provide smaller amounts of the vitamin.
Canadian and British researchers reviewed 37 previous studies giving data on the levels of vitamin D in the blood of about 1,600 seniors. All the participants were over the age of 65 and had no symptoms of dementia and followed for an average of six years. Dementia was diagnosed in 171 people and 102 study participants were diagnosed with Alzheimer’s disease.
Those participants with low whose blood levels of vitamin D had an increased (53%) chance of developing dementia. compared to those with normal levels of vitamin D. Those who had severe deficiencies had a 125% greater risk of developing cognitive problems.
Alzheimer’s disease was more likely (70%) to develop in those with low vitamin D levels, but a severe deficiency increased the likelihood by over 120 percent.
The level of vitamin D in the blood is affected by the foods people eat; the supplements, if any, they take; and exposure to the sun. Vitamin D is naturally present in very few foods. Fatty fish (salmon, tuna, and mackerel) and fish liver oils are the best sources. Cheese, beef liver, and egg yolks provide smaller amounts of the vitamin.
Fortified foods provide most of the vitamin D in our diets. Almost all milk sold in the US is fortified with vitamin D, and foods like breakfast cereal, orange juice, and margarine may also be fortified, depending on the brand.
Llewellyn said that clinical trials are needed to determine whether eating more vitamin D-rich foods or taking supplements can delay or possibly prevent dementia and Alzheimer’s disease. He cautioned that the results of this study did not determine that low vitamin D levels cause dementia, but added that the findings are encouraging given the devastating and expensive nature of these two diseases.
It is estimated that about 70 percent of Americans are deficient in vitamin D. The Recommended Dietary Allowance for vitamin D for adults up to the age of 70 is 600 IU per day. Those 71 and older should get 800 IU per day.
The study is published in Neurology.