Skip to content

Don't Take This Vitamin Anymore, Experts Warn

Doctors reveal which vitamins to stay away from and why.

Supplements are commonly taken to help maintain good health and combat a vitamin deficiency, but many experts question the validity of vitamins due to lack of regulations, harmful side effects and the ineffectiveness of many. Americans have been taking vitamins for decades, but do they really help? Dr. Jagdish Khubchandani, MBBS, Ph.D. Professor of Public Health New Mexico State University says, "Vitamin pills cannot counter the effects of poor diet, lack of exercise, remaining isolated or indoors all the time, drinking or smoking a lot- these habits independently affect physical and mental health and one must stay away from these." Eat This, Not That! Health talked to experts who explained the hidden dangers of vitamins and warned which ones to stay away from.  Read on—and to ensure your health and the health of others, don't miss these Sure Signs You've Already Had COVID.


Do Your Research

older woman using laptop

Dr. Jae Pak, M.D., of Jae Pak Medical explains, "Many people turn to supplements because they feel good about doing something natural for their bodies that is thought to improve health, but they don't always live up to their hype. The purity of supplements depends largely on the manufacturer, and it is sometimes hard to say which are good or bad. That said, my advice is to fully vet the supplier where you are purchasing supplements, and always speak to your doctor before adding any vitamins into your routine." 


Harmful Side Effects

young woman with nausea in all denim outfit sitting on bed
Shutterstock / New Africa

Vitamin consumption in the form of pills has to be carefully measured, Dr. Khubchandani warns. "Vitamins are not candies that people can consume as much as they want. Taking too many pills can cause acute side effects such as vomiting, nausea, diarrhea, confusion, etc. Chronic side effects depend on the type of vitamin consumed in high amounts over time. Depending on the type of vitamin, chronic side effects can range from kidney stones to kidney failure, liver failure, excessive weight loss, hemorrhage, fractures, heart and brain diseases (cardio and cerebrovascular problems)."

RELATED: Signs You Have Memory Loss, Say Experts


Evening Primrose

Evening primrose oil in a glass bowl, with fresh evening primrose flowers in the background.

Nancy Belcher, PhD., MPA says, "Evening primrose oil is a botanical that is said to help relieve hot flashes, but inflammation, blood clotting problems, nausea, diarrhea and a suppressed immune system are possible side effects." 


Dong Quai

Dang gui (angelica sinensis) and dang gui ginseng slice on wooden spoon, traditional chinese herbal medicine.

Belcher states, "Dong quai, which has been used in Chinese medicine to treat gynecological conditions for more than 1,200 years, should never be taken by people who have fibroids or blood clotting problems, as bleeding complications may occur."

RELATED: Signs Omicron is in Your Body, Say Experts


St. John's Wort

st johns wort

Dr. Ani Rostomyan, a Doctor of Pharmacy , Holistic Pharmacist and Functional Medicine Practitioner who specializes in Pharmacogenomics and Nutrigenomic 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."


Diet Supplements

Dietary supplements, vitamins, plate

Dr. Khubchandani, MBBS, Ph.D. Professor of Public Health New Mexico State University explains, "One of the most wasteful and rising trends is the use of diet supplements.From a $1billion business of these products, we are now looking at more than $30 billion in sales of these supplements. No one tests these supplements for efficacy and they are not well regulated. They create a false sense of security and wellbeing among people. In fact, studies show that most of the common diet supplements have negligible effects or possibly, harmful effects. The worst among these diet supplements could be weight loss supplements that can have many side effects and harmful long term effects. Unfortunately, they are marketed heavily and consumers are attracted because so many people want to lose weight, feel healthier, and not seek proper medical care when needed."




Biotin is a popular supplement that some people take for several reasons. According to WebMD, "It is also commonly used for hair loss, brittle nails, and other conditions, but there is no good scientific evidence to support these uses."

New York City dermatologist, Dr. Dina Strachan says, "Taking biotin can cause a false diagnosis of hyperthyroidism or suggest that a thyroid hormone dose is too high.  Biotin interferes with the laboratory tests to measure thyroid function."

RELATED: Places You Shouldn't Go Even if They're Open, According to an MD


Be Careful of Iron Supplements

Red pills of Iron supplements

Lisa Richards, a nutritionist and author of the Candida Diet states, "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." 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 about Heather