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I have a lot of questions about vitamin D.
Our bodies synthesize vitamin D from exposure to sunlight and absorb it from many foods. Vitamin D is important for bone health, and you may have heard about observational studies suggesting that people with high blood levels of vitamin D have many more positive health benefits, including improved health. not. Cardiovascular and brain health.
However, there is compelling research showing that vitamin D supplements do not seem to convey all of the expected health benefits and holes in the claims that many people are vitamin D deficient. I keep coming across articles that poke at me.
Now that winter is coming to an end, those of you who live in cold northern climates and spend most of your weekdays sitting indoors (like me) may be thinking about vitamin D. thought. So I called the leader of the largest randomized vitamin D trial ever conducted and asked if he could help me separate fact from fiction.
This researcher’s name is Dr. Joan Manson. He is the chief of preventive medicine at Brigham and Women’s Hospital and a professor of medicine at Harvard Medical School. She is also the principal investigator of the Vitamin D and Omega-3 Trial (VITAL), which followed approximately 26,000 participants across the United States over her five-plus years.
Manson said vitamin D is actually a hormone that stimulates receptors on almost every cell in the body. This may help explain why there was so much optimism about the potential to improve health.
However, she said the results of randomized clinical trials involving VITAL do not support many of the expectations for vitamin D, at least when taken alone. Here are some highlights from our conversation.
Vitamin D supplements have “limited effectiveness”
Participants in the VITAL trial took 2,000 IU of vitamin D3 softgels daily, 1 gram of omega-3 capsules daily, both supplements, or a placebo.
Manson and her colleagues found no effect of vitamin D supplementation on cardiovascular disease. [or] “We’re looking at the overall incidence of cancer,” she told me. It also had no effect on reducing depression, cognitive decline, atrial fibrillation, or macular degeneration. Researchers found that the supplements did not even significantly reduce the risk of bone fractures.
“This interpretation does not mean that vitamin D doesn’t matter, but rather that we only need small to moderate amounts of vitamin D,” Manson says. “Most people get enough vitamin D from their diet and from occasional sun exposure to reap its benefits. Even supplementing with vitamin D has very limited benefits. ”
Cancer, autoimmune diseases, new coronavirus
Some of the most promising evidence from the VITAL trial was in advanced and metastatic cancers. Although overall cancer diagnoses did not decrease, researchers did notice a reduction in cancer deaths among participants who took vitamin D supplements.
“[It’s] suggesting that vitamin D may play a role in influencing tumor biology, [or] The tumor itself may be less likely to become invasive or metastatic, making it less likely to become a deadly cancer,” Munson said.
Another promising area is autoimmune diseases such as rheumatoid arthritis and psoriasis.
“We saw [a] There was a 22% reduction in autoimmune diseases,” Manson told me. “We know that vitamin D improves immune function and reduces inflammation. That’s why we are currently using vitamin D to reduce the severity of COVID-19 and prevent the prolongation of COVID-19. We hope to publish our results by the end of this spring. ”
There were hints in the data that Black adults may benefit more than other groups from vitamin D supplementation, which reduces memory loss and invasive cancer overall, but Munson said further research is needed on this. warned that it was necessary.
Another interesting finding suggests that people with a BMI below 25 are more likely to benefit from supplements than people who are obese or overweight. But more exploration is still needed, Munson said.
Vitamin D deficiency myths
Although most of the participants in the VITAL study were not vitamin D deficient, Munson stressed that vitamin D deficiency is a known risk to bone health and must be treated. Those at highest risk of deficiency include: These include nursing home residents, people taking osteoporosis medications, and people with certain medical conditions such as Crohn’s disease or celiac disease. But for most other people, testing or supplements are not necessary.
If you’re concerned about your vitamin D levels, Manson recommends eating more foods rich in vitamin D, such as fortified dairy products, wild mushrooms, and fish like salmon, sardines, and tuna.
You can go outside for 15 minutes during the day a few times a week, but you should avoid prolonged exposure to the sun without sunscreen as it can increase your risk of skin cancer and skin aging. she said.
If you’re still concerned, Munson said taking a daily vitamin D supplement of 1,000 to 2,000 IU per day is a “very reasonable” option, especially during the winter months. “We know that long-term that dose is very safe,” Munson told me.
“But it’s not mandatory to do that,” she added.
Manson recommends resisting any advice that recommends megadoses.long-term She said the safety of doses such as 5,000 IU or 10,000 IU a day has not been thoroughly tested.
Go outside and take a multivitamin
One of the biggest takeaways from our conversation is to exercise outdoors if possible. Physical activity is great for your health, and in addition to vitamin D, it can have benefits like improving your mood and feeling connected to nature. I’m also strongly considering adding a multivitamin to my daily routine.
Manson said there is evidence that multivitamins are “much more powerful” when it comes to cognition than vitamin D as a standalone supplement. One of the large placebo-controlled trials known as the COSMOS trial Recently, we found promising evidence that a daily multivitamin can slow memory loss and cognitive decline in older adults.
Of course, it would be great if one pill could magically improve many aspects of your health. But, as Manson points out, vitamin D and other nutritional supplements “are in no way a substitute for a healthy diet and a healthy lifestyle.”
“Being physically active outdoors is almost like a magic bullet for future health,” she says.
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