Health & Wellbeing

Trial finds vitamin D supplements may reduce risk of autoimmune disease

Trial finds vitamin D suppleme...
Over a five-year follow-up, a trial found lower rates of autoimmune disease in those taking vitamin D supplements compared to those taking placebo
Over a five-year follow-up, a trial found lower rates of autoimmune disease in those taking vitamin D supplements compared to those taking placebo
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Over a five-year follow-up, a trial found lower rates of autoimmune disease in those taking vitamin D supplements compared to those taking placebo
Over a five-year follow-up, a trial found lower rates of autoimmune disease in those taking vitamin D supplements compared to those taking placebo

New data from a large placebo-controlled clinical trial investigating the effects of daily vitamin D and omega-3 use indicates the supplements may reduce the risk of developing autoimmune disease. At the five-year follow-up, the trial found those taking vitamin D alone, or in conjunction with omega-3, showed lower rates of autoimmune disease compared to those taking placebo.

Called VITAL, the ongoing trial has enrolled more than 25,000 participants who were randomly assigned to one of four groups: vitamin D and omega 3 (2,000 IU plus 1 gram of fish oil per day), vitamin D plus placebo, omega-3 plus placebo, or double placebo. At the time of recruitment the participants were aged over 50 and generally healthy.

The trial has been running for over five years now and several studies have already been published looking at the effect of these supplementations on cancer risk, cardiovascular risk and depression. For the most part, the trial has found little benefit to vitamin D and omega-3 supplementation in otherwise healthy subjects.

This latest analysis of the trial data looked at the emergence of newly diagnosed autoimmune diseases during the five-year trial. Autoimmune diseases in the trial included rheumatoid arthritis, polymyalgia rheumatica, autoimmune thyroid disease, psoriasis, and inflammatory bowel disease.

Overall, after five years, those taking either vitamin D alone or vitamin D alongside omega-3 displayed significantly lower rates of autoimmune disease compared to those in the placebo group. Little difference was seen in rates of autoimmune disease between the placebo group and those taking omega-3 alone, suggesting the benefits detected were primarily due to vitamin D supplementation.

Another important finding was the longer the trial went on, the lower the risk for autoimmune disease in the vitamin D group. Looking at the data from just the last three years of the trial saw 39 percent fewer cases of autoimmune disease in the vitamin D group compared to placebo. This suggests the greatest benefits of vitamin D supplementation in terms of autoimmune disease comes from a cumulative effect over several years.

"This is the first direct evidence we have that daily supplementation may reduce AD [autoimmune disease] incidence, and what looks like more pronounced effect after two years of supplementation for vitamin D,” said senior author Karen Costenbader. “We look forward to honing and expanding our findings and encourage professional societies to consider these results and emerging data when developing future guidelines for the prevention of autoimmune diseases in midlife and older adults."

This study is, of course, not without limitations. Despite the large number of trial participants and the robust protocol there was a relatively small volume of autoimmune disease diagnoses. Due to the slow onset of many autoimmune diseases a longer follow-up will be necessary to better understand the efficacy of these supplements as preventative tools.

The trial also solely focused on older healthy adults so there is no indication the results are transferable to younger populations or those already diagnosed with autoimmune disease. However, Costenbader is relatively comfortable recommending the vitamin D/omega-3 combination to those over the age of 50 looking for ways to reduce their risk of autoimmune disease.

"Now, when my patients, colleagues, or friends ask me which vitamins or supplements I'd recommend they take to reduce risk of autoimmune disease, I have new evidence-based recommendations for women age 55 years and older and men 50 years and older," noted Costenbader. "I suggest vitamin D 2,000 IU a day and marine omega-3 fatty acids (fish oil), 1,000 mg a day – the doses used in VITAL."

Another recently published study looking at vitamin D and overall mortality tracked more than 20,000 people taking either vitamin D or a placebo for several years. It found no difference in all-cause mortality or from cancer and cardiovascular disease when comparing the vitamin D group and placebo.

The new study was published in the journal The BMJ.

Source: Harvard Gazette

I'd be curious to know if it helps aid with patients who already have an auto-immune disease.
One limitation of these studies is the lack of data correlated to blood levels of D. Oral intake of D3 has a wide bioavailability range (10x). The amount of sun exposure is also a factor unrelated to the oral dose of D3. Studies have shown that it would take a daily dose of 5,000 IU to bring 90% of the population up to a meaningfully therapeutic blood level of 40-60 ng/ml for diseases such as cancer. An oral dose of 2,000 IU as in this study can only hint at the benefits of an oral dose that is customized individually to a target blood level.

The same limitation also goes for the omega-3 fish oil supplement. Once again it takes a blood test to know how much to take to get to a therapeutic level. 1,000mg per day of anti-inflammatory omega-3 oil is pretty low when trying to offset the high omega-6 pro-inflammatory intake in the typical western diet.

Other cohort studies have shown the benefits of both of these supplements when measured against the actual blood levels.

This can not be a one-size-fits-all solution with anything less than 5,000 IU D3 per day. However, once we know that it is beneficial, can it be ethical to have a placebo-controlled study? It is also quite expensive and would have difficulty with compliance levels to have a large-scale study that measures blood levels, so I am not holding my breath to see this trial repeated properly.

Personally, I have been participating in a cohort study on D3 for many years now. I require a lot more than 5,000 IU per day to reach a target blood level. My fish oil requirement is 3x of their study and I eat a very low omega-6 Mediterranean diet. At an advanced age, I am reaping the health benefits.
Did the study consider whether there is any toxicity in taking vitamin D supplements? Do a search on that term "is there any toxicity in taking vitamin D supplements", and you will find several responses which say there can be.
@see3D, exactly, one wonders whether they controlled for location of the subjects. A northerner who spends a higher proportion of their time indoors might already start with vitamin D deficiency due to lack of sun exposure.