To Your Health: Vitamin D

One of the most common questions I get is what supplements do I personally take regularly.

In full disclosure, I take very few supplements, since I think whole foods beat a supplement every day. But one of the exceptions in my diet is vitamin D. However, I dose based on blood tests that monitor my levels.

The fact is we all need 13 vitamins to live: A, C, E, and K, plus 8 B vitamins (thiamin or B1, riboflavin or B2, niacin or B3, folic acid, pantothenic acid or B5, biotin, pyroxidine or B6, and B12) – and D.

Most of those vitamins come from foods – and multivitamins, but very few foods naturally contain vitamin D: fatty fish and eggs are exceptions. Synthesis of vitamin D in our skin (through sun exposure) and foods fortified with vitamin D are two major sources.

What illnesses is vitamin D deficiency associated with?

Rickets, in which bone development is delayed and deformed, is caused by vitamin D deficiency. And for most of the 20th century, scientists defined a person’s daily requirement of vitamin D—called the recommended dietary allowance, or RDA—as the level needed to prevent rickets. We now understand we were being short-sighted tying levels to rickets and ignoring a constellation of other diseases.

Vitamin D and its metabolites have a significant clinical role because of their interrelationship with calcium homeostasis and bone metabolism. The main question we doctors are grappling with currently is what other beneficial effects does vitamin D have on our bodies and what are the appropriate blood levels.

Some of these answers will become evident in 2016. We await the anticipated June 2016 results of the Vitamin D and Omega-3 Trial (VITAL), a randomized clinical trial that is looking hard cardiovascular disease outcomes as they relate to the role of vitamin D and omega-3 supplementation. The problem with this study is that vitamin D may not help cardiovascular disease, but what about other diseases such as autoimmune challenges including inflammatory bowel disease.? What about brain health?

A study published in June 2014 in the British Medical Journal looked at 25-hydroxy vitamin D concentrations in 26,018 subjects and eliminated confounders such as season of the year, country differences, age, and gender prior to coming to the following conclusion: “Robust Evidence Links Very Low Levels of Vitamin D to All-cause Dementia and Alzheimer’s Disease.”

In a recent study, individuals older than 60 years of age showed markedly low levels of 25-hydroxy vitamin D [25(OH)D] with several markers for inflammation, including high-sensitivity C-reactive protein (hsCRP).

Inflammatory biomarkers were significantly higher when vitamin D levels were <25 nmol/L (very low) as compared to >75 nmol/L.

In another recent study for women, a level of 40 nmol/L was associated with the lowest myocardial infarction risk; for men, it was 75 nmol/L.

The Institute of Medicine has proposed a cutoff of 50 nmol/L as being the minimum amount of vitamin D to maintain bone health.

American Geriatrics Society [AGS]) suggests a minimum level of 30 ng/mL (75 nmol/L) is necessary in older adults to minimize the risk of falls and fractures.

We have also noted there is a significantly lower incidence of Crohn’s disease and ulcerative colitis in areas of the world with more sunshine.

Emerging evidence suggests vitamin D supplementation may be a potential therapy for treatment of active disease or prevention of relapse in Crohn’s disease, investigators wrote in the United European Gastroenterology Journal. Those findings are providing the first preliminary clinical data suggesting vitamin D may help maintain intestinal integrity in Crohn’s disease, a fact that appears to be supported by emerging evidence from other experimental studies.

What about diabetes?

A number of studies tracking healthy people for years have reached the same conclusion: “People with higher levels of vitamin D have a lower risk of developing type 2 diabetes in the future.”

In a provocative study, those taking vitamin D (either alone or with calcium) had better pancreatic beta­ cell function than those who did not take vitamin D.

Vitamin D has major effects on nearly all cells of the immune system.

In my practice, for 11 years and counting, I have routinely checked vitamin D levels, especially in patients with autoimmune diseases.

As we wear more and more sunscreen (which is appropriate) and larger hats and live farther from the equator, however, we are faced with increasing vitamin D deficiency. Where I live in the Midwest, about 90 percent of the patients we see in my practice are insufficient or severely deficient.

The elderly and African-Americans are especially vulnerable to vitamin D deficiency, so supplementation (preferably in natural form, vitamin D3, cholecalciferol) should quite likely be routine for those groups.

Ok, so we’ve established that as with most vitamins, with vitamin D there are verified and emerging risks of deficiency.

There are also risks of toxicity with excessive amounts, particularly with fat soluble vitamins such as A, E – and D.

Fat soluble vitamins easily build up in the body, so I check labs yearly. If someone is extremely D deficient, I follow a peak at the end of the summer and a trough at the beginning of spring until I have the appropriate dosing schedule.

We have a lot to learn about vitamin D – as well as all vitamins. Until we have better data, be wary of excessive doses.

And for those of you who are curious: I take 2,000 iu of vitamin D a day. My levels have been steady now for years at around 47 ng/ml.

Is that the best level?

Hopefully we will have much better data available next year!

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