We get it - if you're going to the trouble of swallowing your daily supplements, you want to know the best time of day to take it. There's no point in spending money on extra vitamins and minerals if they're not going to get absorbed that well, or you're just going to pee it out.
Which is why people are curious about the best time to take probiotics and vitamins - in particular vitamin D, a nutrient that most people in the United States do not consume enough of, according to the National Institutes of Health (NIH). Weirdly, that doesn't mean many Americans are truly deficient in it - when participants in the ongoing National Health and Nutrition Examination Survey (NHANES) had their blood levels tested, just 5% were at risk of deficiency. That may be because many of them got added vitamin D from sun exposure - aside from consuming it through supplements or food, your body makes its own vitamin D when it's exposed to the sun.
But you can't get all you need through sun exposure alone (especially because we all need to be protecting ourselves from the sun's damaging rays) and you may not be getting what you need through the food you eat. That's why it's "very reasonable," to take a supplement to be sure, says JoAnn Manson, M.D., MPH, DrPH, a Professor of Medicine at Harvard Medical School and chief of the Division of Preventive Medicine at Brigham and Women's Hospital in Boston.
Dr. Manson is one of the directors of the ginormous and ongoing VITAL study, which is looking at whether taking vitamin D3 or omega-3 fatty acid supplements reduce the risk of various major conditions. The study found that most people do not need to take a vitamin D supplement to avoid being deficient, but that it's safe to take 1000-2000 IU a day as a type of insurance. "Most multivitamins have vitamin D, so that is one way to do it," she says.
Vitamin D helps you absorb calcium, which of course helps to build and maintain strong bones. In fact, the two - calcium and vitamin D - together can help protect you from osteoporosis, a disease that weakens your skeleton and makes bones more likely to break if you should fall, adds Carol Haggans, MS, RD, a spokesperson for the NIH Office of Dietary Supplements. Your muscles also need it to do their thing, as do your nerves, which carry messages between your brain and your body. Oh, and without vitamin D, your immune system would be less adept at fighting off bacteria and viruses.
Most of us - healthy adults between 19 and 70 - should try to consume 600-800 IUs, says Haggans (the recommended amounts are different for healthy people who are older or younger.)
But some folks need more than the suggested amount for their age group. Breastfeeding moms should take note: "It's recommended to give breastfed infants a supplement, because breastmilk doesn't provide infants with enough vitamin D," says Haggans.
Others who may need more vitamin D that the recommended amounts:
It's also important to make sure you don't overdo it. "More is not better, and megadosing should be avoided," says Dr. Manson. The upper limit per day for everyone over 9 years old is 4000 IUs, unless you've been screened by your doctor and have issues specific to you that they feel require a higher dose. Extremely high levels can cause symptoms like vomiting, muscle weakness, confusion and pain, among others, according to the NIH; extremely high levels can lead to kidney failure, irregular heartbeat and even death.
It just plain doesn't matter, as long as you take it with food, says Dr. Manson. Her advice: Take it when you'll remember to take it - morning, noon or night - and take it with a meal, she says. "It is important that it be taken with food, because vitamin D is a fat-soluble vitamin," meaning it does not dissolve in water and is absorbed with fat, so it is better if there's a little healthy fat to mix it up with, says Dr. Manson. "Often it will come in a soft gel with a little oil in it to help it absorb, but it's still best to take it with food."
Both vitamin D2 and D3 are good, but "D3 has better bioavailablilty," says Dr. Manson, meaning that it's more easily used by your body.
But that doesn't mean any old brand will do. Dietary supplements are not approved by the FDA prior to going to market, so we recommend that you do a bit of research or ask your doctor for a good brand. You'll want to look for options that have been third-party tested for purity, potency and safety and can confirm that what is on the label is actually what is in the bottle - look for NSF or USP logos on the label.
Below, you'll find some picks that have been recommended by the experts in the Good Housekeeping Institute.