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I'm a Doctor and Warn You Know This Before Taking Vitamins

10 things to know before taking vitamins, doctors say.

Millions of people take vitamins on a regular basis to stay healthy, but they may not provide the benefits you think, according to some doctors. Experts warn it's important to thoroughly research each brand, understand the potential risks and consult your physician first. Eat This, Not That! Health talked to several doctors and medical experts who explained what to know before taking vitamins. Read on—and to ensure your health and the health of others, don't miss these Sure Signs You've Already Had COVID.


Don't Take Vitamins in Substitute of a Healthy Diet

mediterranean diet

We can get a lot of our vitamins from having a healthy diet. Dr. Jacob Hascalovici says, "It's true that aging can make it a bit more difficult to get all the nutrients women's bodies need to stay strong and healthy, but that doesn't mean that women always need to turn to supplements for their vitamins and nutrients. If you have concerns, you may want to evaluate your overall eating habits first — you may already be getting enough nutrients if you're eating a wide range of colorful fruits and vegetables along with whole grains, nuts, beans, low-fat dairy and lean proteins. It may also be a good idea to talk to your doctor or nutritionist before adding in a supplement, as people's specific nutritional needs can vary. It is possible to ingest certain vitamins and supplements in higher than ideal levels, which can have negative impacts over time, which is why there's no one-size-fits-all approach when it comes to nutritional supplements." 


Many Vitamins Are Not Regulated

Headquarters of US Food and Drug Administration (FDA)

"The purity of supplements depends largely on the manufacturer, and it is sometimes hard to say which are good or bad," Dr. Jae Pak, M.D., of Jae Pak Medical explains. "That said, my advice is to fully vet the supplier where you are purchasing supplements, and always speak to your doctor before adding any vitamin into your routine. [Vitamins] are not regulated by the Food and Drug Administration, which means even the most expensive vitamins may not be as pure as you think they are. Some products contain more fillers than actual helpful ingredients, so it is important to know and trust the manufacturer you're sourcing them from."


There's Harmful Interactions with Vitamins and Certain Medications

Pharmacist wearing protective hygienic mask and making drug recommendations in modern pharmacy

Dr. Pak warns, "Another thing many don't consider when taking vitamins and supplements is that they could interact with other medications and supplements you're taking. They may also have harmful side effects in addition to any perceived benefits. For these reasons, it is important to consult with a trusted health care provider before beginning any vitamin or supplement regimen."

Dr. Ani Rostomyan is a Doctor of Pharmacy, Holistic Pharmacist and Functional Medicine Practitioner who specializes in Pharmacogenomics and Nutrigenomic consulting says, "From a Pharmacist standpoint, always inform us about vitamins and herbal supplements you take, since some may interact with medications, like St. John's Wort may interact with some medications due to impaired metabolic pathways of certain medications, through  induction of cytochrome P (CYP) 1A2, 2C19, 2C9, and 3A4, as well as intestinal P-glycoprotein/multidrug efflux pump (MDR)-1 drug transporters."


Consider Food First

Happy woman eating healthy salad sitting on the table with green fresh ingredients indoors

Rachel Fine, a Registered Dietitian and owner of To The Pointe Nutrition  says, "In general multivitamins are not technically needed if one is eating a diet abundant in a variety of plant based foods. However, given our busy schedules and reliance on convenient options it may be beneficial for women to consider multivitamins as a means of filling in the gaps."

Dr. Pak adds, "A well-balanced, colorful diet is the best way to fill nutritional gaps. I recommend exploring professional nutrition counseling before heading down the slippery supplements slope." 


Be Cautious with Megadoses

middle-aged woman looking at supplement bottles
Shutterstock / Dean Drobot

Fine explains, "The most common deficiencies in women are calcium, vitamin D and iron. Since there's no standard formula for multis composition, it can vary greatly. It's important to make sure your tablet is not overdoing it with some nutrients. For example I suggest choosing a tablet with no more than 1000 IU of vitamin D and no more than 500 mg calcium. If you're getting in 2-3 servings of calcium-containing foods (like dairy) in your diet then you may choose a tablet with a more modest amount of calcium (100-400mg)."


Consider Timing

Woman holding pills on her hand.

"One advantage of taking a vitamin with a lower amount of calcium (such as 200mg) is that there is less of a chance of the calcium interfering with iron absorption," Fine states. "If you tend to be deficient in iron (which is quite common for menstruation women) it's best to take your multi separate (at least 2 hours) from your iron supplement."


Ask Yourself Why You Need Vitamins

A woman is looking through her medicine cabinet.

Dr. Rostomyan says, "Everyone's needs are unique and can't be standardized to one size fits all, health care providers will be able to decide and recommend your own nutritional needs based on your health needs, status and preferences. For example, living in certain geographical areas, like northern countries, may put you at a greater risk for Vitamin D deficiency, or if you are abiding certain vegan diets, you may be more prone to iron or vitamin B group deficiencies."


What to Know If You're Pregnant or Considering Getting Pregnant

Female doctor is checking pregnant woman with stethoscope

It's always important to take care of your health, but especially during pregnancy. Dr. Hascalovici explains, "Women sometimes can benefit from specific nutritional support, however, including from supplement powders, particularly if they are pregnant or are trying to become pregnant, are trying to increase muscle mass, are vegetarian or vegan, or are over 50. Calcium, vitamin D and the B vitamins might be worth looking into if you fit one of these categories. You'll likely want to choose powders from natural instead of synthetic sources, and you may benefit from whey or soy protein powders, too."

Dr. Kecia Gaither, MD, MPH, FACOG, double board-certified in OB/GYN and Maternal Fetal Medicine, Director of Perinatal Services at NYC Health + Hospitals/Lincoln in the Bronx, also recommends vitamin D. 

"It's beneficial for a multitude of bodily functions. Aids with bone development for both mother and fetus. It also boosts immunity- pregnancy has a physiologic immune suppression on the body such that the fetus can thrive. Vitamin D has been shown to aid in diminishing symptoms of depression, is good for cardiovascular health and decreases the incidence of preterm labor. For melanated individuals, it's important to know that Vitamin D is made in the skin in conjunction with sunlight– this process is inhibited by melanin– it's important to get your levels checked. 


Don't Take Calcium and Iron Together

woman takes medicine capsules

Lisa Richards, nutritionist and author of the Candida Diet explains, "When it comes to taking an iron supplement, or a multivitamin which contains iron, it is important to avoid taking calcium or consuming calcium around the same time. The term elemental iron refers to the amount of iron that is absorbed from each capsule. There are two forms of iron; heme (from animal sources) and non-heme (from plant-sources). Heme iron is absorbed at approximately 25% while non-heme is absorbed at around 17%. Most iron supplements on the market are made from non-heme sources, which is great for vegan dieters, but should be paired with a vitamin C source for better absorption. All iron supplements should be taken at least 2 hours pre or post-meal to prevent the mineral from having to compete with other minerals for absorption, specifically calcium."


Consider Nutrigenomic Testing

Woman technician with multipipette in genetic laboratory PCR research

Dr. Rostomyan reveals, "Due to advances in science in genomic and precision medicine and nutrition, Nutrigenomic testing has become also used to determine unique personalized nutritional needs of a person, based on Nutrigenomics testing. As a Pharmacogenomics and Nutrigenomics Pharmacist, I find it very helpful to run the Nutrigenomic testing and take the guesswork out of the way, helping patients to incorporate personalized nutrition and vitamin supplementation." And to get through this pandemic at your healthiest, don't miss these 35 Places You're Most Likely to Catch COVID.

Heather Newgen
Heather Newgen has two decades of experience reporting and writing about health, fitness, entertainment and travel. Heather currently freelances for several publications. Read more