Vitamin D and Cognitive Function

A new study, published in the Journal of Geriatric Psychology and Neurology, suggests that low levels of vitamin D may be linked to an increased risk of cognitive impairment in older adults.

Vitamin D helps the body absorb calcium and phosphorous. Recent research also suggests that vitamin D may help prevent osteoporosis, high blood pressure, cancer and several autoimmune diseases. Two forms are important in humans: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamins D2 and D3 are found in many dietary sources such as fish, eggs and fortified milk. The sun also helps the body produce vitamin D3. 

As people age, their ability produce vitamin D from sunlight and to convert vitamin D into its active form decreases. Therefore, older adults have an increased risk of vitamin D deficiency. 

The cross-sectional study included 1,766 adults in the Health Survey for England 2000 who were 65 years of age and older. The authors measured the participants' vitamin D blood levels and assessed their cognitive function using the Abbreviated Mental Test Score.

A total of 212 participants (about 12 percent) were considered cognitively impaired. Vitamin D levels were lower in these participants compared to those with normal cognition. In fact, about half of cognitively impaired participants had the lowest blood levels of vitamin D (8-30 nanomoles per liter of blood). According to the authors, individuals with the lowest vitamin D levels were 2.3 times more likely to develop cognitive impairment than those with the highest levels.

Early laboratory and animal studies suggest that vitamin D may have neuroprotective effects. However, human studies in this area are limited, and a potential mechanism for this effect is unclear.

This latest study is limited by its cross-section design. Additional research is warranted in this area to fully understand the potential neuroprotective effects of vitamin D.

For more information about vitamin D, please visit Natural Standard's Foods, Herbs & Supplements database.

Comments

[jeffrey Dach, MD]

I have noticed that, thanks to the efforts of Dr John Cannell, many mainstream docs in my area have begun to order vitamin D tests and supplement when found to be low.

Satellite maps of the earth showing UV Sunlight exposure correlate with serum vitamin D levels, and the farther north, the lower the vitamin D, and the higher the incidence of cancer and multiple sclerosis in our population.

These NASA space satellite photos of North America color coded for UV sun exposure can be seen on Dr. Grant's vitamin D Web site. Here, you will see a pattern remarkably similar to the incidence of cancer and multiple sclerosis. This is thought to be due to differences in vitamin D levels. The farther north with less sun exposure and lower vitamin D levels, there is an increased incidence of cancer and multiple sclerosis.

Again here is the list of diseases caused by, or associated with, vitamin D deficiency: osteoporosis, hypertension, cardiovascular disease, cancer, depression, epilepsy, type 1 diabetes, insulin resistance, autoimmune diseases, migraine headache, polycystic ovarian disease (PCOS), musculoskeletal and bone pain, psoriasis.

Vitamin D deficiency has been reported in 57% of 290 medical inpatients in Massachusetts, 93% of 150 patients with overt musculoskeletal pain in Minnesota, 48% of patients with multiple sclerosis, 50% of patients with lupus and fibromyalgia, 42% of healthy adolescents, 40% of African American Women, and 62% of the morbidly obese, 83% of 360 patients with low back pain in Saudi Arabia, 73% of Austrian patients with ankylosisng spondylitis, 58% of Japanese girls with Graves’s disease, 40% of Chinese adolescent girls, 40-70% of all Finnish medical patients. (the above is from Dr Cannell newsletter)

Surprisingly, we have been seeing low vitamin D levels even here in sunny Florida, demonstrated by serum 25-OH Vit D blood testing. These people avoid the sun for fear of skin cancer.

To read a synopsis of Dr John Cannell's excellent work...

http://jeffreydach.com/2007/06/10/vitamin-d-deficiency–by-jeffrey-dach-md.aspx

[anna roy]

Maybe this is why seniors really flock to the sunbelt! Since I'm sure this study on the importance of vitamin D might motivate people to get more sun, it seems like a smart time for a reminder about sun safety: wear sun block and protective clothing and a hat, avoid peak midday hours...you know the drill.

And it's also important to note that a number of medications, including heart drugs, obesity meds and even laxatives, can interfere with vitamin D absorption. Given that seniors also tend to take many more medications, I wonder if this plays a significant role in depletion of vitamin D?

[Alissa]

Researchers have found evidence that a direct interaction between vitamin D and a common genetic variant alters the risk of developing multiple sclerosis. The research suggests vitamin D deficiency in the mother during pregnancy and a child's early years may increase the risk of that child developing MS later in life. Previous studies have shown that people living in northern countries with reduced sunlight have an increased risk of developing the progressive neurological disease, and Canada has one of the highest MS rates in the world. The researchers found that vitamin D interacts with a section of DNA known to contain a gene that makes a person more susceptible to developing MS.

[Damion]

To play devil's advocate: skeptics doubt many of the health claims of vitamin D and question the need and even the validity of widespread testing. They recall how large doses of vitamins C and E were supposed to prevent cardiovascular disease. Beta-carotene was supposed to prevent lung cancer. Selenium kept prostate cancer at bay. None of it turned out to be true, and some of the advice even proved harmful.

[Lucy]

This is good news to the indoor tanning industry, which was being vilified by doctors linking it to rising rates of melanoma. In 2003, the industry created a nonprofit outfit called the Ultraviolet Light Research and Educational Foundation to promote the idea that UV light doesn’t just give you a tan, it could save your life. The foundation declared February – a midwinter month when indoor tanning is most popular – “Vitamin D Deficiency Month.”

[Wahge]

This is very interesting. Few questions though: was this a retrospective observational study? The author just stated the possible benefit of vitamin D, but did not say if the researchers describe the mechanism in which vitamin D may provide cognitive benefits.

[Luce]

This is a good place to start research. I hope another group of researchers, or may be the same researchers, will look further into this. But this time around, they should follow the patients with low serum vitamin D levels, supplement them and assess their cognitive function. This would help us understand if vitamin actually has anything to do with cognitive impairment.

[GWB]

I think that all of this is very important information. Something we need to keep in mind though is too much supplementation with vitamin D, I am assuming that this would be bad for you. Does anyone know what over-supplementation causes (maybe suppression of PTH)?

[Bia]

This is very interesting because I've heard of many people in the northern part of the U.S. that are being diagnosed with low vit D levels. The way they are treating this is with 5000 milligrams of vitamin D taken once a week.

[Vinnie]

This is the first time I've heard that vit D affects cognitive function. I've always heard that it has a major role in calcium absorption, and the main source of it comes from the sun. I also learned that you have to do a specific blood test to just test vit D, so that is why people are deficient, and the doctors don't know.

[Meredith]

I was listening to a program on TV, and the guy was stating that vit D has been shown to decrease cancer by more than 50 percent. These patients have to be taking a supplement of vit D alone in order to receive the sufficient amount. The amount of cancer seen in the northern part of the U.S. is much higher than the southern part, which implies that the lack of sunlight in the north is decreasing the levels of vit D and therefore leading to cancer.

[Marcie]

Anna, you bring up an important point. It's all about balance. Even though vitamin D consumption is important, overdoing sun exposure is not the answer. I think people have to remember the same when eating foods. Consuming tons of dairy to get more of your vitamins is probably not going to help much either.

[Edson]

I agree that vit D is being looked at more closely nowadays. If the deficiency of this vitamin has been shown to increase the chance of cancer, cognitive dysfunction and calcium absorption, then every age range can be affected.

[Stella]

GWB,

Vitamin D toxicity can cause nonspecific symptoms, such as nausea, vomiting, poor appetite, constipation, weakness, and weight loss. More seriously, it can also raise blood levels of calcium, causing mental status changes such as confusion and heart rhythm abnormalities.

The Women’s Health Initiative (over a seven-year period) found that postmenopausal women who used supplements of both calcium (1,000 mg/day) and vitamin D (400 IU/day) had a 17% increase in the risk of kidney stones. Deposition of calcium and phosphate in the kidneys and other soft tissues can also be caused by excessive vitamin D levels. A serum 25-(OH)-vitamin D concentration consistently >200 ng/mL (>500 nmol/L) is considered to be potentially toxic.

[Olu King]

To add to Stella’s comment above, excessive sun exposure does not result in vitamin D toxicity because the sustained heat on the skin is thought to photodegrade previtamin D3 and vitamin D3 as it is formed. High intakes of dietary vitamin D are very unlikely to result in toxicity unless large amounts of cod liver oil are consumed; toxicity is more likely to occur from high intakes of supplements.

Also long-term intakes above the upper limits increase the risk of adverse health effects. Substantially larger doses administered for a short time or periodically (e.g., 50,000 IU/week for eight weeks) do not cause toxicity. Rather, the excess is stored and used as needed to maintain normal serum 25-(OH)- vitamin D concentrations when vitamin D intakes or sun exposure are limited.

[Ines]

I just had blood work done to see if I was vit D deficient, and I am. I had signs that would indicate this deficiency. I would like to think that my cognitive function is good, but maybe it will improve now that I am taking 5000mg of vit D once a week.

[Haldir]

The prevalence of vitamin D deficiency worldwide as suggested by the statistics seems to be alarming. Malnutrition is obviously a problem worldwide. It would be interesting to see if the World Health Organization has any recommendations or plans to help curb the progression of disease if the relationship between these diseases and vitamin D deficiency are established.

[AM]

Vitamin D deficiency has been linked to many conditions. Interestingly, the data available regarding what is considered a deficiency are not definite. The value that is considered deficient varies depending on what condition the study is looking at. I found an interesting article regarding cardiovascular health and vitamin D published from the American Heart Association journal, Circulation. After reading this article and many other sources, I think we should just all supplement ourselves with vitamin D and calcium as part of our daily regimen, regardless of whether we are deficient or not.

http://www.americanheart.org/presenter.jhtml?identifier=3054554

[Supplements from Foods]

A Canadian company, Naturally Nova Scotia, makes supplements from foods instead of synthetics. They have vitamin C from fruit, herbal tinctures, green drinks, vitamin D3 and others.

[Brianna]

Vitamin D is a key factor in calcium absorption, so those older patients who don't leave the house much (and therefore get less Vitamin D through sunlight) probably have a greater risk of falling at home (due to decreased calcium absorption -> osteoporosis). It is a big cycle that should encourage us to stay balanced with diet, exercise and all other aspects of our lives.

[Jo]

Lucy, I don't know if this is necessarily good news for the tanning industry -- or at least, it shouldn't be. I sure hope studies like these don't cause people to flock to tanning beds in order to increase vitamin D, but only end up with skin cancer down the road.

[Sean]

Low levels of Vitamin D in the body may be responsible for weight gain in women. Results of a study conducted in California indicate that compared with the vitamin D sufficient women, same-age counterparts with insufficient vitamin D levels were heavier by about 7.4 kilograms (about 16.3 pounds) on average. The vitamin D insufficient group also averaged 3.4 points higher in body mass measurements.

[Howie]

Vitamin D is found in the following foods: dairy products, including cheese, butter, cream, fortified milk (all milk in the U.S. is fortified with vitamin D); fish; oysters; fortified cereals and margarine.

[Seema]

The association between serum concentrations of vitamin D and the activity of inflammatory polyarthritis was studied in London, England. This study involved more than 200 patients with signs of early inflammatory polyarthritis. The authors found that patients with higher level of vitamin D had lower activity of polyarthritis.

[Sandra]

A meta-analysis of vitamin D3 and the risk of falls and fractures was conducted. The analysis included nine studies. The inclusion criteria consisted of a comparison between vitamin D and placebo and their respective risk effects on the risk of fractures and falls. The researchers found that vitamin D3 may be associated with a trend toward a lower risk of falls.