But are you wasting your money on vitamins and minerals you don’t need or possibly harming yourself by taking high doses? Here’s the lowdown.
Adding supplements only makes sense for some of us, experts say, such as the elderly, pregnant women, breastfeeding babies and people who have certain diseases or conditions that affect absorption of nutrients, potentially resulting in nutritional deficiencies.
In fact, mitigating nutritional deficiencies is where supplements “are best utilized” according to Craig Hopp, deputy director of the division of extramural research at the National Center for Complementary and Integrative Health, part of the US National Institutes of Health.
“Anytime somebody is missing major food groups, the first question is, can we target the missing nutrients with food? If not, then we would look into a supplement,” said registered dietitian nutritionist Melissa Majumdar, who is a spokesperson for the Academy of Nutrition and Dietetics.
But there’s a big difference between taking a pill as “nutritional insurance” if your diet is low in one or more nutrients versus taking it in the hopes of warding off disease. And even if you’re popping a pill to simply up your vitamin C or calcium intake, health professionals agree it’s not a substitute for a healthy diet.
“Eating a healthy diet is going to do far more for you than any supplement you can take, and yet we have a whole industry that is based on selling us all types of supplements,” said Martha H. Stipanuk, James Jamison professor of nutrition emeritus in the division of nutritional sciences at Cornell University.
“When we look at health outcomes, no one supplement will have the effect of an overall healthy diet, in terms of immunity or chronic disease.”
“Fruits and vegetables have phytochemicals and fiber; when you pop a pill, you never get the same outcomes,” said Lisa Young, a registered dietitian nutritionist and adjunct professor of nutrition at New York University.
Experts worry that high doses of nutrients can give a false sense of promise.
“Often you feel you won’t necessarily have to concentrate on getting these nutrients from your diet,” said Young, who added that she often sees this with clients in her private practice. “You might feel like, ‘This is insurance and I don’t have to eat well,’ and it might have a negative effect.”
Supplements: The state of the science
“At the moment, evidence to support the use of individual vitamins and minerals for treatment or prevention of chronic disease outcomes is weak,” Hopp said.
“A diet high in fruits in vegetables includes [lots of] vitamins and minerals … and is epidemiologically associated with reduced instance of a whole host of chronic diseases,” Hopp said. “But we have not seen that you can dietary supplement your way to good health. They are dietary supplements, not substitutes.”
“There are some data that support benefits of certain supplements on specific outcomes, but many recent systematic reviews are concluding that, for most supplements, we have insufficient quality data to allow us to make strong recommendations,” Stipanuk added.
Studies are usually relatively short-term — two or three years at the most — and many lack appropriate control groups, Stipanuk explained. And when there are positive outcomes in observational studies, researchers can’t necessarily prove that the supplement is responsible for the beneficial effect.
Too much of a good thing
In fact, high doses of some vitamins and minerals — particularly vitamin A, vitamin D, niacin, folic acid, calcium and iron — can build up to toxic levels and have adverse side effects.
For example, once you are over 50, you are at very low risk of iron deficiency, and there is no need for iron supplements, Stipanuk explained, but you could develop gastrointestinal irritation or more serious iron deposition in the liver and other tissues if excess iron is routinely taken.
“We want to sway people away from taking supplements without the guidance of a registered dietitian nutritionist or medical professional that understands the pathways and interactions of a particular nutrient,” said Majumdar, who added that taking too much zinc can interfere with iron or calcium absorption, and could potentially cause deficiencies of these minerals.
“There are upper limits of safe intake, and it’s very easy to exceed those limits for some nutrients when you combine various food sources of a nutrient, including fortified foods, along with a supplement and a multivitamin,” Stipanuk said.
“You don’t want to be taking one thing from too many sources,” Stipanuk advised. “The various sources could add up to an amount that far exceed need, and that may have an adverse effect.”
Digestive problems can occur in some people, even with proper doses. “Some say I can’t take calcium carbonate because I get a stomachache or that iron is constipating,” Young said.
Because each person’s needs are so different, it’s important to ask your doctor to refer you to a registered dietitian nutritionist. (Registered dietitian or registered dietitian nutritionist are the correct terms — technically anyone can say that he or she is a “nutritionist,” but only those who have met criteria established by the Academy of Nutrition and Dietetics can call themselves an RD or RDN.)
Where supplements make sense
Here’s where supplements can come in handy, according to guidelines from national health organizations. Before you add any supplements to your diet, however, meet with a health care provider who can determine what is best for you based on your individual health history and lifestyle habits.
If you are pregnant, consult your OB/GYN for a prenatal vitamin recommendation.
Postmenopausal women: If you are postmenopausal or at risk for osteoporosis and you avoid dairy and other food sources of calcium like almonds, tofu or canned salmon with bones, consider a calcium and vitamin D supplement, to help keep bones strong and reduce bone loss.
To optimize calcium absorption, consume no more than 500 milligrams at one time.
For vitamin D, “consider how much vitamin D you routinely get from fatty fish and fortified milk (or other products), and choose a supplement on the lower side, perhaps 100% or less of the RDA,” Stipanuk advised.
The daily upper limit for vitamin D is 4,000 IU for children 9 years and older, adults and pregnant and lactating teens and women.
Eye, heart, gastro and other conditions:
Treatment with omega-3 supplements is reasonable for those with “prevalent coronary heart disease such as a recent MI,” however, according to the 2017 advisory. (MI stands for myocardial infarction, another term for heart attack).
And if you avoid fish entirely, aim to increase your consumption of plant-based omega-3s such as chia, flaxseeds and walnuts. You can also consider taking an algae oil supplement, which mimics the nutrients from fish, Majumdar explained.
Iron, calcium and vitamin B12, among other vitamins and minerals, are common deficiencies in these groups of patients.
Medication interactions: Additionally, some medications can interact with nutrients and affect their absorption.
Athletes: Endurance athletes could be at risk for iron deficiency as a result of sweat loss, lack of iron intake and breaking down of red blood cells with repeated foot strikes, Majumdar said, though she added that athletes should check iron levels before considering an iron supplement.
Calcium supplementation among female athletes may be necessary, depending on one’s dietary intake of calcium. And athletes with a history of stress fracture, bone or joint injury, signs of overtraining or muscle pain or weakness may require an assessment of vitamin D intake.
Supplement savvy: What to look out for
Because supplements are regulated as food and not drugs, they don’t have to prove that they are safe or even that they work before they are sold in stores. Be a savvy consumer by following this guidance:
Avoid mega doses, and look for 100% of the Daily Value for vitamins and minerals. According to Young, “1,000% [of the Daily Value] is a red flag.”
The USP logo “is a pretty good indication of a company who is trying to produce a high-quality product,” Hopp said. “It identifies that the product meets standards for identity, quantity and purity,” Majumdar added.
You can also look for the NSF logo on products. According to Stipanuk, NSF independently certifies some supplements such as fish oils and multivitamins and their ingredients.
The program tests products or ingredients for harmful levels of contaminants and certifies that supplements contain the ingredients listed on the label and contains no unsafe levels of contaminants such as heavy metals, pesticides and herbicides.
Keep in mind, supplement manufacturers cannot claim that their product will diagnose, cure, mitigate, treat or prevent a disease. “Raise a red flag if the supplement is claiming any of the above or if your interpretation is leading you down that direction,” Majumdar said.
“Instead of taking a supplement because you think it can prevent a disease, talk to a registered dietitian nutritionist about what can,” Majumdar added.
Lisa Drayer is a nutritionist, an author and a CNN health and nutrition contributor.