Unless there is a breakthrough in the prevention, treatment, or cure of dementia and Alzheimer’s disease, the number of people age 65 and older who will have Alzheimer’s disease by 2050 is expected to triple, from 5.1 million today to 13.8 million. While we’re waiting for the medical experts to come through for us, there is something you can do to reduce your risk of these life-altering conditions: take vitamin D.
It’s estimated that about half the world’s population has a deficiency of vitamin D. The relationship between low or deficient vitamin D and Alzheimer’s disease / dementia has been studied for years, and the most recent findings strongly support the idea that low levels of vitamin D are associated with a greater risk of developing these neurological diseases. How strong is that relationship? Two recent studies illustrate it.
International Dementia/Alzheimer’s Study
An international team evaluated data from 1,685 elderly Americans who did not have dementia at the start of the study. The participants were followed for about five years, and at the end of that time, here’s what the experts observed:
- 171 individuals had developed dementia, of which 102 had Alzheimer’s disease.
- Among those with dementia, individuals with low vitamin D levels were 53 percent more likely to develop the disease than were those with high levels of the vitamin.
- Among participants who were severely deficient in vitamin D, the risk was 125 percent.
- When considering participants who had developed Alzheimer’s disease, low vitamin D levels increased the risk by 69 percent, while a severe deficiency caused the risk to rise by 122 percent.
According to the study’s lead author, Dr. David Llewellyn of the University of Exeter Medical School, “the results were surprising-we actually found that the association was twice as strong as we anticipated.” However, he cautioned that their findings don’t show that low levels of vitamin D cause dementia.
Second International Study
A different international team analyzed data on 1,291 individuals from the US Cardiovascular Health Study (CHS) and 915 participants from the Dutch Longitudinal Aging Study Amsterdam (LASA). All of the subjects were dementia-free at the beginning of the studies and were evaluated using either the Benton Visual Retention Test or Rey’s Auditory Verbal Learning Test.
In the CHS study, participants who were moderately and severely deficient in vitamin D demonstrated a greater change in visual memory per year when compared with their peers who had sufficient amount of the vitamin.
In the LASA group, a moderate and severe deficiency in vitamin D were associated with a nonsignificant change in verbal memory when compared with those who had a sufficient level of vitamin D.
Where To Go From Here
The results of these studies should encourage people to pause and consider having their vitamin D levels tested, which involves a simple blood test. Regardless of age, it’s never too early to get an adequate amount of vitamin D, since this nutrient is involved in so many critical processes and a lack is associated with serious health conditions, such as cancer, diabetes, multiple sclerosis, tuberculosis, depression, brittle bones, heart disease, and the common cold.
Since few foods (egg yolk, fatty fish, fortified cow’s milk) provide a sufficient amount of vitamin D and it would be challenging to eat enough of them to meet most people’s needs, the two alternatives are exposure to sunlight and supplementation. This one statement mentions three factors you need to consider:
- How much vitamin D is considered to be sufficient? Different experts and organizations have differing ideas on this daily amount. The US Food and Nutrition Board recommends 600 International Units (IUs) and 800 IUs for seniors; the Endocrine Society suggests 1,500 to 2,000 IUs; and the Vitamin D Council recommends 5,000 IUs. Sufficient blood levels of vitamin D are 40 to 80 ng/mL (Vitamin D Council recommendation); greater than 20 ng/mL (Food and Nutrition Board); and 30 to 100 ng/mL (Endocrine Society).
- The amount of time to spend in the sunlight. This depends on the time of day, where you live, your skin color, altitude, whether it is cloudy, your age, and the amount of skin you expose to the sun. However, as a general rule, you should get just enough sun so your skin begins to turn pink and you should expose as much skin as possible (without sunscreen). Be careful not to get sunburned.
- The recommended amount of supplement to take. This amount depends on how much you are getting from your diet and sunlight. Especially as people get older, it often becomes more common to depend on vitamin D supplements to meet a person’s daily needs, as those mentioned above.
Although there’s much we still do not understand about Alzheimer’s disease and dementia, research has uncovered a variety of ways to help reduce the risk, including diet, supplementation, and lifestyle changes. Vitamin D supplements appear to be among those preventive steps.
Kuzma E et al. Vitamin D and memory decline: two population-based prospective studies. Journal of Alzheimer’s Disease 2016 Jan 21
Littlejohns TJ et al. Vitamin D and the risk of dementia and Alzheimer disease. Neurology 2014 Sep 2; 3(10): 920-28
US News and World Report. Are you getting enough vitamin D?