Low Vitamin D Linked to Brain Fog

New research suggests that vitamin D-deficient older adults may have a higher risk of developing dementia or other cognition problems.

January 11, 2010

Smart move: To stay sharp as you age, keep vitamin D in the equation.

RODALE NEWS, EMMAUS, PA—Scientific evidence suggests that vitamin D deficiencies can affect health in people of all ages in many ways. Now, a pair of studies published in January's Neurology suggests a link between insufficient levels of the vitamin and dementia, Alzheimer's disease, and general cognitive impairment in older adults.

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THE DETAILS: In one study, researchers looked at adults between the ages of 65 and 99 who were receiving home care, and found that those living with dementia had lower levels of vitamin D than the other participants. After adjustments were made for age and sex, researchers discovered that vitamin D insufficiency and deficiency were associated with a twofold higher risk of dementia, Alzheimer's disease, and stroke. In the second study, French researchers investigated vitamin D levels and cognitive impairment among 752 women, age 75 and older, and found a connection between deficient levels and cognitive problems, like memory difficulty and trouble processing simple math problems. More research is needed to establish the robustness of the connection, though; a third study published in the journal did not find a strong link between vitamin D levels and cognitive decline in a group of 1,600 older men.

WHAT IT MEANS: Though the importance of vitamin D to mental functioning needs further study, the vitamin has long been known to be necessary in helping your body absorb calcium for stronger bones. And emerging research is finding that the vitamin, which is actually a fat-soluble hormone, is vital to healthy functioning of many of our bodies' systems. In the past few years, there have been more and more studies suggesting that low vitamin D levels in the blood can cause health problems in children and adults. Studies have linked low levels of vitamin D, known as "the sunshine vitamin" because our body makes it naturally when sunshine hits our skin, to higher risk of certain cancers, of falling in older adults, and of diabetes, asthma, and a weaker immune system. Altogether, the evidence makes a strong case for everyone to make sure he or she is getting enough.

Here's what all ages need to know about vitamin D.

• Older adults should consider supplementing to stay steady. A study published in 2009 in the British Medical Journal found that adults 65 and older taking a supplement of 700 to 1,000 International Units, or IU, (that's how vitamin D is measured) reduced their risk of falls by nearly 20 percent. So even though the researchers in the latest studies call for more studies on vitamin D's effect on cognition, it's probably a good idea to talk to your doctor about supplementation now.

• Get the blood test. No matter what your age, ask your doctor for a simple 25(OH)D blood test that can determine if you have sufficient levels of the vitamin. If your levels are insufficient or you're deficient, consider supplementation. Many experts are recommending at least 1,000 IU a day for adults, and children should receive at least 400 IU of vitamin D. It can be hard to get enough of the nutrient without taking a supplement, since otherwise, you can only get the vitamin from unprotected sun exposure (and only during spring and summer months in latitudes north of Atlanta), along with very few food products (fatty fish like salmon and mackerel, and fortified milk, juices, and cereals).