A recent article in Forbes suggested that Vitamin D is a useless vitamin and should be thrown away. Needless to say, the article elicited several questions in the clinic. First, is Vitamin D important as a daily supplement, and second, how can research guide health decisions when studies are often contradictory?
The Forbes article Stop Taking Vitamin D Already by Steven Salzberg cites a 2014 analysis of a “massive review of 462 other studies that concluded Vitamin D did not help prevent heart disease, weight gain, mood disorders, multiple sclerosis, and metabolic disorders. The conclusion was low [blood] levels of Vitamin D are a result of bad health, not a cause.” Salzberg then cites a single study in 2014 on bone health and Vitamin D that concludes that “vitamin D supplements do not improve bone density, and do not reduce the risk of osteoporosis.” (a )
I wonder at Salzberg telling readers to throw away their Vitamin D supplements when an analysis of Vitamin D’s most significant benefit, supporting the immune system, is omitted. In fact, his article directly contradicts other articles published in Forbes showing that Vitamin D levels are critical in reducing the risk of contracting Covid, improving recovery from Covid, and reducing the risk of dying from Covid (b,c,d), compelling reasons for taking Vitamin D.
Contradictions in research are not unusual. A quick search through PubMed uncovers over 12,500 studies showing Vitamin D3 supplementation as both beneficial and not.
For example, here are two beneficial studies:
A 2017 study in Clinical Exp Immunology concludes that vitamin D supplementation is beneficial in the treatment of Cystic Fibrosis due to its ‘immunomodulatory effects.” (e)
Another study concludes that while Vitamin D supplementation did not reduce ‘all cause mortality’, it “reduced the risk of cancer death by 16%.” The paper called for further clinical studies. (f)
Here are two studies on the same topics with negative findings:
A 2019 placebo-controlled study found no benefit in any participants using vitamin D supplementation on pulmonary function in Cystic Fibrosis. (g)
There are so few studies with negative findings on Vitamin D and cancer, that I gave up looking. You can search yourself on PubMed. It’s free.
The reason research is contradictory is often due to the study design.
Discrepancies in bone health studies might be due to whether vitamin D3 is being combined with other nutrients necessary for its absorption, such vitamin K2.
A 2020 study reported in Gynecology- Endocrinology concluded that, in regards to osteoporosis, patients who were deficient in Vitamin D gained “a maximal benefit from vitamin D supplementation.” The conclusion is that you have to need Vitamin D for taking it to be helpful. (h) It’s worth noting that vitamin D deficiency is rarely required for participants in research studies.
Research at the Buck Institute takes a step back to look beyond simple cause and effect of Vitamin D to its role as an anti-aging agent and the effects of ageing on disease. (i) This indirect approach may have significant implications.
Another impact on study design is bias. Every study has inherent bias. Finding it helps us understand conflicting results. Even the keywords used in a google search and the studies that are chosen to discuss are impacted by bias. For example, when we follow financial bias, celebrities making $800,000 per day selling vitamins might provide other’s with an excuse for thinking vitamins are scams, and vitamin sellers are scammers. At the same time, the billions of dollars pharmaceutical companies make selling drugs presents a conflict of interest when a big pharma company undertakes vitamin research that results in negative conclusions.
Salzberg does not conceal his own financial bias. His concerns are for taxpayers having to pay for research into vitamin D conducted at the National Institute of Health, and for insurance companies having to pay for vitamin D testing. In writing this blog, I admit my own bias. I want to find natural remedies for people’s health because it supports my belief that given the right conditions, the body can heal itself. We all have bias. When looking at conflicting studies identify the inherent bias and look for how it impacts the design and outcome. Look at your own bias to judge the source of your reaction to differing studies.
Here are some tips for Vitamin D supplementation:
Vitamin D deficiency is very common. According the NIH, 42% of the U.S. population is deficient. (J)
Until recently, the acceptable range of Vitamin D was 30 to 100 ng/ml. Now ranges are being adjusted to a lower level of 20 ng/ml and upper range of 50 to 80 ng/ml. In Naturopathic practice, we consider a range of 50-70 ng/ml to be optimal as opposed to acceptable.
Always know your vitamin D status. If you don’t need it, don’t take it. Overdosing is as serious as deficiency and much harder to correct. Ask your doctor for a requisition for the blood test, or pay and order the test yourself at labs that don’t require a doctor’s order such as www.directlabs.com.
The correct form of Vitamin D to take as a supplement is D-3. If you don’t know your Vitamin D status, studies show that 1,000 iu per day is generally safe and some studies indicate the upper limit for supplementation is 10,000 iu per day.(K)
Formulas that combine D3 with K2 are better absorbed and utilized. (L)
The majority of studies show Vitamin D3 is good for all aspects of health. It helps fight cancer, covid, the flu, colds, osteoporosis, rickets, liver disease, kidney disease, mental health, and other serious illnesses while boosting your immune system.
References
FYI: Often, Forbes articles are not found using links. Putting the article title in your search engine can work better.
Clin Exp Immunol. 2017 Sep;189(3):359-371. doi: 10.1111/cei.12984. Epub 2017 May 24. https://pubmed.ncbi.nlm.nih.gov/28470739/
BMJ. 2019; 366: l4673. Published online 2019 Aug 12. doi: 10.1136/bmj.l4673 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6689821/
Am J Clin Nutr. 2019 Mar; 109(3): 544–553., Published online 2019 Feb 22. doi: 10.1093/ajcn/nqy291
Gynecol Endocrinol, . 2020 Feb;36(2):93-95. doi: 10.1080/09513590.2019.1650346. Epub 2019 Aug 7.
https://pubmed.ncbi.nlm.nih.gov/21310306/