In the United States, vitamin D is the most popular supplement, while fish oil (an omega-3 fatty acid supplement) is third on that list, according to a recent market study. In fact, they are the goose that lays the golden eggs: the supplement industry is worth over a billion.
But despite what the label may promise, scientists know little about what these supplements actually do to benefit the body or brain, and are still looking at who precisely might benefit from taking them. Now, however, they are getting closer, as a new study suggests that vitamin D supplementation may be linked to a positive immune effect.
A new data analysis published in The British Medical Journal says that people who take vitamin D regularly are less likely to develop autoimmune diseases than those who don’t. Autoimmune conditions like lupus or rheumatoid arthritis arise when the body’s own immune system goes rogue and attacks healthy tissue.
The same analysis found less clear links between taking fish oil supplements and autoimmune diseases, but the results here are a bit more complicated.
What does the scientific community say about these supplements?
Vitamin D supplements can help many people who don’t get enough vitamin from their food or from sunlight; in fact, too little vitamin D can compromise bone and dental health.
Some scientists also believe that vitamin D does more than help the body absorb calcium. And there is evidence to suggest that it has health benefits. cognitive and cardiovascular, and may play a role in the immune system.
On the other hand, fish oil has been shown to lower cholesterol and arthritis and relieve symptoms of ADHD (attention deficit hyperactivity disorder), with research even suggesting it decreases inflammation. But the data so far is not overwhelmingly conclusive.
Proof of how many times researchers have tested vitamin D and fish oil for various medical uses is in the extensive fact sheets from the National Institutes of Health (NIH) Office of Dietary Supplements. The problem is that most of the evidence falls short of that institution’s standard for recommending a supplement for use beyond those stated above. However, the new analysis hints at a different benefit.
How was the new study conducted?
The data in the new study comes from a wealth of health information and research collected from the study. VITAL (vitamin and omega-3 assay). In 2010, scientists wanted to study the effect of vitamin D and fish oil on cancer prevention and cardiovascular health over the course of at least five years.
The study included 25,871 adults with no serious health problems at the start. Some received vitamin D (at 2,000 international units per day), others fish oil (at 1,000 milligrams per day), others received both, and another group received a matching placebo. But this was all random; people didn’t know if they were in the supplement or placebo groups.
All participants agreed to limit the amount of vitamin D they took outside of the trial to no more than 800 IU per day (the upper end of the NIH recommended daily dose) and agreed not to start taking fish oil at all.
The initial results, published in 2018, are not a resounding endorsement of vitamin D or fish oil for cancer or cardiovascular health. But ultimately, the study and its data have served as the basis for researchers to return again and again to investigate this topic.
It was a long-term, placebo-controlled study involving thousands of people from relatively diverse backgrounds. And out of that came the new study: Current researchers looked at the rate of autoimmune disease in VITAL study participants.
What do the results indicate?
Over the course of five years or more, people taking vitamin D were found to be 22 percent less likely to develop an autoimmune disease. After two years, the difference was widening: People in the vitamin D group had 39 percent fewer diagnoses than people in the placebo group. This finding suggests that taking the supplements over time may be key to the protective effect hinted at here.
Meanwhile, people taking fish oil appeared to be 15 percent less likely to be diagnosed with an autoimmune disease, although this is not statistically significant, according to the researchers. However, when they took into account people who had symptoms of an autoimmune disease but no diagnosis, the rate jumped to 18 percent, which is statistically significant.
On the other hand, people taking vitamin D and fish oil may fare even better: In this group, participants had 30 percent fewer autoimmune disease diagnoses than the placebo group.
There are many autoimmune diseases, all of which have varying degrees of severity and effect on a person’s quality of life. As many as 23.5 million Americans have one, and some of them have shorter life expectancies than the general population.
Like all chronic health problems, autoimmune diseases can decrease a person’s quality of life. For example, inflammatory bowel disease, which can manifest as Crohn’s disease or ulcerative colitis, was the most common diagnosis among VITAL study participants.
This disease can cause diarrhea, fatigue, abdominal pain and cramps, blood in the stool, and unintentional weight loss. The thing is, together, these symptoms can hamper a person’s ability to participate in everyday activities that others take for granted, like going to work, traveling, or just dining out.
So is it good to take vitamin D and fish oil?
Vitamin D supplements are plentiful and non-toxic, so while their effect on immunity is still up for debate, taking them may not hurt.
One-third of American adults are deficient in vitamin D, and medical professionals largely agree that supplements can help people get enough vitamin D (and may even be better than sunlight due to cancer risk) of skin). You can also incorporate more foods rich in vitamin D in your diet: from fortified cereals and milk to oily fish, such as salmon or mackerel.
According to the authors of the new analysis, the results suggest that vitamin D represents a simple intervention that could reduce the burden of autoimmune diseases. This is explained in the document:
“Autoimmune diseases are a heterogeneous group of conditions with similar underlying pathogenic mechanisms and together are associated with considerable morbidity and mortality. The clinical importance of these findings is high, because these are well-tolerated non-toxic supplements, and other effective treatments to reduce the incidence of autoimmune diseases are lacking. Additionally, we saw consistent results across all autoimmune diseases and increasing effects over time.”
As for the use of fish oil, it is something that is still being deliberated. But like vitamin D, fish oil can also come from the diet. Either way, it’s best to check with your doctor before making any major changes to your diet or if you want to take supplements for the first time.