To the growing list of health problems that aren’t likely to be eased or prevented by taking vitamin D supplements (provided you aren’t deficient in the vitamin), you can add chronic knee pain and depression, according to two of the latest analyses from the landmark clinical trial called VITAL (VITamin D and OmegA-3 TriaL). That study tested vitamin D pills (as well as supplements of omega-3 fatty acids, or fish oil) against a placebo in nearly 26,000 generally healthy adults 50 and older. We reported on its earlier results in our February 2019 and May 2020 Wellness Letter issues.
The first of the latest papers, in Arthritis & Rheumatology in June 2020, examined data from 1,398 VITAL participants who had chronic knee pain due to osteoarthritis. Over an average of five years, there was no significant difference at any point in participants’ reported pain, stiffness, or function—such as the ability to climb stairs, rise from sitting, or get in and out of a car—between those who were randomly assigned to take vitamin D (2,000 international units, or IU, a day of D3) or omega-3s (1 gram a day) and those who took a placebo. The supplement users also were no less likely overall to need a total knee replacement, and they used about the same amount of pain medication, including opioids.
The second analysis, in the Journal of the American Medical Association in August 2020, included 18,353 VITAL participants who had either no history of depression or no depressive episode in the two years prior to the start of the study. Those who took vitamin D were no less likely than those in a placebo group to be newly diagnosed with depression or (if they’d had depression previously) to have a recurrence of depression over the next five years. Nor did vitamin D improve mood scores compared to placebo. The authors concluded that “the findings do not support a role for supplemental vitamin D3 in depression prevention among adults.” The study did not look at the effect of omega-3 pills on depression.
What to do: If you don’t know if your vitamin D level is adequate (as established by a blood test), we continue to advise taking a modest supplement (800 to 1,000 IU a day) to ensure that you’re meeting the recommended daily intake. That’s because of the many health problems that have been associated with low blood levels of vitamin D and not because taking extra D will confer special health benefits, which is looking ever less likely. Select groups might need more supplementation, including people who take medication that can interfere with vitamin D metabolism, such as some cancer therapies and antiseizure drugs.
