The Sun Shines on Vitamin D

By Jack Challem, BA

If recent research were a political election, vitamin D would win by a landslide. Over the past five years, more than 10,000 medical journal articles have been published on the vitamin. And the pace of research is accelerating. In just the past year, 3,500 reports have been published on vitamin D, about half focusing on people.

Three of every four Americans are either deficient or have borderline deficiencies of vitamin D (i). Such widespread deficiencies of the “sunshine vitamin” are truly ironic because doctors thought they were vanquished 80 years ago. So the odds are that you need to take it.

Vitamin D is actually a prohormone that the body produces when the skin is exposed to sunlight. It eventually gets converted to calcitriol, a steroid hormone. But when people don’t spend at least 15 minutes in the summer sun, they can’t make much vitamin D. Many experts, including Michael Holick, M.D., of the Boston University School of Medicine, believe that everyone, including babies and children, should take vitamin D supplements.

Here’s a rundown of the latest research.

Live Longer and Healthier
In an analysis of 32 published studies involving almost 160,000 people, Danish researchers found that a combination of vitamin D and calcium supplements reduced the risk of death by 7 percent.(ii) While that finding was modest, other research shows stronger benefits.

Ellen Smit, PhD, of Oregon State University, and her colleagues analyzed 12 years of data from 4,731 people. Vitamin D blood levels were lowest in people who were physically frail—that is, abnormally thin, inactive, walking slowly, or weak. Furthermore, people with low levels of vitamin D were 30 percent more likely to die, compared with those who had higher levels of the vitamin. Smit found that people who were both frail and had low vitamin D levels were three times more likely to die compared with the healthiest subjects.(iii)

Meanwhile, Israeli researchers reported that seriously ill patients are more likely to survive if they have higher blood levels of vitamin D. In this study, Howard Amital, M.D. and his colleagues tracked patients who were hospitalized for life-threatening infections, heart attacks, heart failure, and accidents. The vast majority of the 130 patients had vitamin D deficiencies. People with higher vitamin D levels lived longer.(iv)

Avoiding Physical Disabilities
You need vitamin D to maintain healthy bones and to reduce the risk of osteoporosis. But you also need the vitamin to make muscle, which keeps those bones in place. The latest findings show that vitamin D can protect against disability, age-related frailty, and death.

Researchers at the Wake Forest School of Medicine, North Carolina, analyzed vitamin D levels in 2,099 people and tracked them for a total of six years. At the beginning of the study, two-thirds of the subjects—elderly men and women—were either marginally deficient or had clear-cut deficiencies of vitamin D. People with low vitamin D levels had about a 30 percent greater risk of having some physical limitations and almost twice the risk of disability, compared with people who had higher vitamin D levels.(v)

Meanwhile, Heike A. Bischoff-Ferrari, MD, DrPH, of the University of Zurich, Switzerland, analyzed data from 11 studies in which seniors were given either vitamin D supplements or placebos. More than 31,000 people, age 65 and older, were included in the analysis. Bischoff-Ferrari reported that vitamin D reduced the risk of hip fracture by 30 percent— but only among people who took800 to 2,000 IU of the vitamin daily. In addition, people taking this range of vitamin D dosage had a 14 percent lower risk of other types of fractures, except for those of the backbone.(vi)

Better Resistance to Diabetes
Several studies have found that vitamin D supplements (often combined with calcium) can help people maintain normal blood sugar levels. Researchers at Drexel University, Philadelphia, Pennsylvania, focused on the relationship between obesity, insulin resistance, and vitamin D levels in a study of 12,900 people. People who were obese and had normal vitamin D levels were almost 20 times more likely to have prediabetes. But among people who were obese and had low vitamin D levels, prediabetes was 32 times more common than average. The researchers noted that obese subjects are at high risk of vitamin D deficiency because the vitamin gets stored in fat tissue, preventing it from being used by the rest of the body.(vii)

Surviving Breast Cancer
Maintaining normal to high levels of vitamin D may give women an edge if they’re diagnosed with breast cancer.

Hans Wildiers, MD, of University Hospitals, Leuven, Belgium, evaluated 1,800 women whose vitamin D levels were measured at the time of diagnosis. Low vitamin D levels correlated strongly with larger tumor sizes at the time of diagnosis, whereas higher vitamin D levels were associated with smaller tumor sizes.

Furthermore, breast cancer patients with higher vitamin D levels lived longer. After three years of follow up, postmenopausal women who had high vitamin D levels were more likely to be free of cancer.(vii)

Reversing Early Prostate Cancer
Vitamin D might not prevent prostate cancer, but recent studies suggest that the vitamin can help control the disease in its early stages and reduce the risk of dying from it.

Doctors at the Medical University of South Carolina, Charleston, reported that vitamin D supplements might reverse the growth of early prostate cancer, at least in some men. They studied men with low-grade prostate cancer who took 4,000 IU of vitamin D daily for one year.

When the men underwent follow-up biopsies, more than half of the men benefited from a decrease in their Gleason scores, a way of measuring the aggressiveness of prostate cancer. Five men showed no change, and 15 had an increase in either positive biopsy samples or their Gleason scores. Because vitamin D is so safe, it’s worth taking if you and your doctor agree to “watchful waiting.”(ix)

Meanwhile, a study in the Journal of the National Cancer Institute found that high levels of vitamin D reduce the risk of death from prostate cancer by more than half. (x)

Better Control of Multiple Sclerosis
Many researchers have noted that multiple sclerosis (MS) and vitamin D deficiency often go hand in hand. Doctors at René Descartes University, Paris asked 156 patients with relapsing-remitting  MS to take 3,000 IU of vitamin D daily. They then compared the patients’ relapse rates for a couple of years before starting vitamin D supplements and for a couple of years after taking the supplements.

The changes were dramatic. For every 4 ng/mL increase in vitamin D blood levels, the relapse rate decreased by almost 14 percent. The benefits increased until blood levels of the vitamin climbed to 44 ng/mL. That’s the amount of vitamin D needed to activate a variety of enzymes that depend on the vitamin.(xi)

How Much Should You Take?
Unless you’re spending a lot of time outdoors, and much of your skin is exposed without sunscreen, you’ll need to take vitamin D supplements. John Cannell, M.D., director of the nonprofit Vitamin D Council, recommends that adults simply take 5,000 IU daily. For infants, use vitamin D drops to add up to 1,000 IU daily. For other children and teenagers, 2,000 IU daily.

Do note that vitamin D3 is absorbed far better compared with vitamin D2. And if you’re obese, you’ll need more vitamin D because it gets stored in fat tissue, preventing the rest of the body from using it.

Originally published in Better Nutrition magazine. Reprinted with permission of the author.

i Ginde AA, Liu MC, Camargo CA. Demographic differences and trends of vitamin D insufficiency in the US population, 1988-2004. Archives of Internal Medicine, 2009;169: 626-632.
ii Reynmark L, Avenell A, Masud T, et al. Vitamin D with calcium reduces mortality: patient level pooled analysis of 70,528 patients from eight major vitamin D trials. Journal of Clinical Endocrinology and Metabolism, 2012: doi 10.1210/jc.2011-3328.
iii Smit E, Crespo CJ, Michael Y, et al. The effect of vitamin D and frailty on mortality among non-institutionalized US older adults. European Journal of Clinical Nutrition, 2012: doi 10.1038/ ejcn.2012.67.
iv Arnson Y, Gringauz I, Itzhaky D, et al. Vitamin D deficiency is associated with poor outcomes and increased mortality in severely ill patients. Quarterly Journal of Medicine, 2012: doi 10.1093/
v Houston DK, Neiberg RH, Tooze JA, et al. Low 25-hydroxyvitamin D predicts the onset of mobility limitation and disability in community-dwelling older adults: the health ABC study. The Journals of Gerontology, Series A, Biological Sciences and Medical Sciences, 2012: doi 10.1093/gerona/gls136.

vi Bischoff-Ferrari HA, Willett WC, Orav EJ, et al. A pooled analysis of vitamin D dose requirements for fracture prevention. New England Journal of Medicine, 2012;367: 40-49.

vii Kabadi SM, Lee BK, Liu L. Joint effects of obesity and vitamin D insufficiency on insulin
resistance and type 2 diabetes. Diabetes Care, 2012: epub ahead of print.
viii Hatse S, Lambrechts D, Verstuyf A, et al. Vitamin D status at breast cancer diagnosis: correlation with tumor characteristics, disease outcome, and genetic determinants of vitamin D insufficiency. Carcinogenesis, 2012;33:1319-1326.
ix Marshal DT, Savage SJ, Garrett-Mayer E, et al. Vitamin D3 supplementation at 4000 international units per day for one year results in a decrease of positive cores at repeat biopsy in subjects with low-risk prostate cancer under active surveillance. Journal of Clinical Endocrinology andMetabolism, 2012: doi10.1210/jc.2012-1451.
x Shui IM, Mucci LA, Kraft P, et al. Vitamin D-related genetic variation, plasma vitamin D, and risk of lethal prostate cancer: a prospective nested case-control study. J Natl Cancer Inst, 2012;104:690-699.
xi Pierrot-Deseilligny C, Rivaud-Pechoux S, Clerson P, et al. Relationship between 25-OH-D serum level and relapse rate in multiple sclerosis patients before and after vitamin D supplementation. Therapeutic Advances in Neurological Disorders, 2012;5:187-198.
xii Logan VF, Gray AR, Peddie MC, et al. Long-term vitamin D3 supplementation is more effective than vitamin D2 in maintaining serum 25-hydroxyvitamin D status over the winter months. British Journal of Nutrition, 2012: doi10.1017/S0007114512002851