Vitamin D May Affect Brain Function

Edit Subject

Vitamin D may help to protect the brain, two new studies suggest. One study looked at blood levels of vitamin D in 858 older adults. They also were given tests of various mental abilities. The study lasted 6 years. In that time, people with very low vitamin D levels were 60% more likely than others to have major declines in thinking, learning and memory. They were 31% more likely to have losses in executive function. This is the brain function that deals with organizing and planning. Study results appeared in the journal Archives of Internal Medicine. The other study was in the Archives of Neurology. It included nearly 3,200 older adults. They did not have Parkinson's disease when the study began. During the next 29 years, 50 developed the disease. People with the highest vitamin D levels were 67% less likely to develop Parkinson's than people with the lowest levels.

What Is the Doctor's Reaction?

Could the secret to keeping your brain sharp for a lifetime be as simple as taking a vitamin? Or spending a few minutes in the sun each day? It's possible, two new studies suggest.

The first study enrolled 858 adults who were at least 65 years old. During the next 6 years, people with the lowest blood levels of vitamin D had 60% more decline in memory and thinking than those who had the highest levels.

The second study included 3,173 adults, ages 50 through 79. During the next 29 years, those with the lowest vitamin D levels had a 67% higher risk of developing Parkinson's disease. This is a brain disease marked by tremors and difficulty with movement.

What's the link between vitamin D and brain function? No one knows for sure. Perhaps vitamin D acts as an antioxidant, helping to protect and repair brain cells. Maybe vitamin D helps the immune system or nerve function. It's also possible that vitamin D clears beta-amyloid, a protein that builds up abnormally in the brains of people with Alzheimer's.

These are only the latest studies suggesting a link between health problems and low vitamin D levels. We know that vitamin D plays a vital role in bone health. Very low levels are associated with weak bones that are prone to fracture. Recent research also has linked low vitamin D levels with:

• Heart and blood vessel disease


• Autoimmune diseases, in which the immune system attacks the body's own cells


• Cancer


• Infections


• Type 2 diabetes


• Obesity

The role of vitamin D in bone health is well known. But it's not at all clear whether getting enough vitamin D can prevent dementia, Parkinson's disease or other conditions. Finding "an association" between low vitamin D and a disease is not proof that low vitamin D causes that disease.

What about the risks of vitamin D? In one study, kidney stones were more common among women taking vitamin D pills. And, if you take far too much vitamin D, blood calcium may become dangerously high. But serious side effects from a diet high in vitamin D or from the usual doses of supplements are rare.

What Changes Can I Make Now?

We get vitamin D from foods and supplements. Sun exposure also produces vitamin D through a chemical reaction in the skin. Think about whether you get enough vitamin D. Foods high in vitamin D include:

• Fortified milk, orange juice and cereals


• Fish and fish oil


• Eggs


• Cheese

The value (or risk) of sun exposure is somewhat controversial. Many skin experts advise people to use sunscreen and limit direct sun exposure because of the risks of skin cancer. But 10 to 15 minutes of sun (without sunscreen) may be enough to safely increase your vitamin D levels.

Talk to your doctor about whether you should have your blood vitamin D level checked. Several types of tests are available, but the 25-hydroxy-vitamin D level is the best reflection of overall vitamin D status. A level of 30 to 100 nanograms per milliliter (ng/ml) is considered normal.

Vitamin D deficiency is common, especially in northern climates where days are relatively short and people are bundled up for much of the year. Therefore, some doctors will recommend vitamin D pills for all patients. Others recommend supplements only if the blood level is low. And still other doctors check vitamin D levels only if a person has symptoms or factors that increase the risk of vitamin D deficiency. These include:

• Bone pain or bones that break easily


• Muscle weakness


• Low dietary intake of vitamin D


• Limited exposure to sunlight


• Dark skin


• Kidney disease


• Digestive disease (such as Crohn's or celiac disease)


• Obesity

We don't know what role vitamin D may have in maintaining normal brain function. But it's reasonable to choose a diet rich in vitamin D, get some sun (but not too much!), and consider taking a supplement.

What Can I Expect Looking to the Future?

The possibility that vitamin D can keep your brain healthy is exciting. But we need studies of vitamin D treatment to prove whether it can actually prevent brain disease or other illness. These studies would randomly assign people to take vitamin D or placebo (fake) pills.

Such studies should answer these questions:

• What are the benefits of maintaining a normal amount of vitamin D in the body?


• What is the ideal blood level of vitamin D?


• What are the risks of increasing your dietary intake of vitamin D or of taking supplements?


• How does vitamin D prevent Parkinson's disease or other types of brain disease?

The answers are more than interesting. They could provide insights into why dementia, Parkinson's disease and other common ailments develop in the first place.