With food or without? Morning or night? The answer depends on what supplement you're taking.
According to the Council for Responsible Nutrition’s 2019 Consumer Survey on Dietary Supplements, more Americans are taking dietary supplements than ever before. More than three-fourths (77%) of Americans surveyed reported they consume dietary supplements.
Adults between ages 35 and 54 are the biggest consumers of dietary supplements (81%). Vitamins and minerals were the most commonly consumed supplement category, with 76% of those surveyed reporting they had taken these products in the past 12 months.
Yet the predominance of research, and the advice of nutrition experts, suggests that taking vitamins and minerals is unnecessary for most individuals. “When my patients are able to consume a balanced diet consisting of a variety of foods including fruits and vegetables, I generally don't encourage an additional multivitamin supplementation,” says Kristen Smith, registered dietitian, bariatric surgery coordinator for Piedmont Healthcare in Atlanta and spokesperson for the Academy of Nutrition and Dietetics.
Thus, if you're taking or thinking about taking supplements, the first question to ask is whether you need them. “It is best to consult with a registered dietitian nutritionist to, one, identify if you can meet your needs from food; two, if you should supplement with a multivitamin or individual nutrient based on a health condition, diet gap or risk of deficiency from a medication interaction; and three, whether the supplement could actually be harmful,” says Melissa Majumdar, a registered dietitian, metabolic and bariatric coordinator with Emory University Hospital Midtown in Atlanta and an Academy of Nutrition and Dietetics spokesperson.
Some people certainly can benefit from a vitamin supplement. “In cases when a patient is pregnant, has malabsorption or history of intestinal surgery, is not capable of eating a balanced diet or has a known deficiency, I will recommend a multivitamin to help supplement their micronutrient intake,” Smith says.
For anyone taking a dietary supplement – whether they really need it or not – there are certain guidelines to follow in order to maximize their effectiveness. These can relate to timing, whether to take with or without food and how to avoid taking too much of a nutrient, which could be harmful.
Talk to a Health Care Professional
Once you decide if you need or desire a supplement, talk to a physician or nutrition expert about timing, “based on the specific goal of the supplement,” Majumdar says. A health care professional can help you create a personalized schedule for your vitamin regimen, Smith adds.
As a general rule, most people need to take a high-dose multivitamin/multimineral with food to prevent an upset stomach. “Nutrients found in multivitamins like iron, zinc and B vitamins can make someone feel nauseous if taken on an empty stomach,” Majumdar says. So time your vitamin or mineral with a snack or at mealtime.
But not all snacks or meals fit the bill. “That being said, taking supplements alongside foods high in phytates or tannins can prevent absorption,” Majumdar says. “Foods like whole grains, beans, nuts and seeds are high in phytates, which make great foods for overall diet but not great foods to pair with supplements.” Phytates, she explains, are phosphorus stored in plants; the phytates bind to minerals and make absorption difficult. “Consider taking the multivitamin/multimineral two hours after a meal so your stomach isn't completely empty, but the phytates don't fight the absorption,” she advises.
Fat-soluble vitamins such as vitamin A, D, E and K are typically better absorbed when taken with a fat-containing food such as olive oil, nut butter or avocado, Smith says.
As for when to take vitamins, the evidence is unclear. But some mealtimes make more sense than others, depending on the vitamin or mineral. “The timing of when you take certain vitamins is important, however not necessary to be considered for all of them. Work with your health care professional to determine what is best for you,” Smith says.
To reiterate, most people get all the vitamins they need from a well-balanced diet. A few vitamins, though, are most commonly taken as a supplement, and it's important to understand how to take them safely and effectively.
Iron. Majumdar says that iron is best absorbed on an empty stomach, but can be difficult to tolerate, causing upset stomach, nausea and constipation. “Consider first trying it on an empty stomach, and if not tolerated, take at night before bed,” she suggests.
Taking iron in smaller, divided doses throughout the day can also help with toleration. “Generally, the side effects are mild enough to sleep through, and if you avoid eating a few hours before bed, you can maximize absorption. Iron competes for absorption in the small intestine with calcium and zinc, so taking iron at least two hours apart from these nutrients is ideal,” she says.
Since multivitamins often include iron, consider taking iron separately if it’s needed for a true iron deficiency. But beware of overdosing. “Excess iron is stored in the liver and if taken in excess amounts, can be damaging, so consult a medical professional like a registered dietitian nutritionist before taking iron,” Majumdar says.
The Recommended Dietary Allowance – or the National Food and Nutrition Board's suggested dietary intake – for all age groups of men and postmenopausal women is 8 milligrams a day; the RDA for premenopausal women is 18 mg/day. The Tolerable Upper Intake Level – the maximum dose that can be taken without risking overdose or serious side effects – is 45 mg/day for adults, according to the National Institutes of Health.
A specific type of iron known as heme iron, which is found in meat and other animal products, is better absorbed than nonheme iron, found in vegetarian foods like nuts, seeds and beans. “Heme sources of iron can enhance absorption of nonheme iron, the form in supplements, so taking iron alongside a food with heme-iron, like dark meat chicken or red meat, can help,” she says.
Vitamin C. Food sources of vitamin C, like peppers, oranges, melons and kiwi, can enhance absorption of iron. So, if you are diagnosed with a true iron deficiency, be sure to combine your iron supplements with vitamin C-rich foods or supplements. Consider washing down your iron pill with a glass of orange juice in the morning at breakfast.
Calcium. Many adults and children are not meeting calcium needs from food, Majumdar says. (The National Institutes of Health recommend anywhere from 1,000 milligrams a day for children age 4 to 8 up to 1,300 mg a day for teens, adults and pregnant or lactating women.) Not only is calcium often deficient, but this mineral also requires vitamin D to be absorbed. “And with vitamin D being one of the most common deficiencies among Americans, one should first have vitamin D levels checked,” Majumdar says. “If not treated, calcium will not be properly absorbed, and the body will borrow calcium from the bone to keep blood levels stable.”
Calcium may affect how the body absorbs iron, zinc or magnesium, Smith says; “consider taking calcium at least two hours apart” from those minerals. Also, the form of calcium is important. “Calcium citrate can be taken with or without food, but calcium carbonate requires an acidic environment to be broken down, so taking alongside food can increase the calcium digestion,” Majumdar says.
It's believed that the body cannot absorb more than 500 to 600 milligrams at one time, so “calcium may require taking in split doses throughout the day,” Smith says.
Vitamin D. Along with helping the body absorb calcium and keep bones strong, vitamin D is necessary for muscle, nerve and immune system health. The skin uses sunlight to manufacture this vitamin, but many people, especially in northern latitudes in winter, fail to make enough. Likewise, very few foods contain vitamin D, except those fortified with the vitamin, like cereals and milk products. Supplements are helpful, but too much can be harmful – from stomach distress to, in extreme cases, kidney failure, irregular heartbeats and death. Upper limits are 100 micrograms per day for anyone over age 9, so consult with a dietitian or physician before starting this or any dietary supplement.