Many households have a cabinet stocked with various vitamins and dietary supplements promising better sleep, healthier hair, or improved digestion. Most people grab them without much thought, assuming more is better and that anything sold without a prescription must be perfectly safe. But Rojina Shams Nateri, a pharmacist at Roseway Labs, is raising the alarm about a widespread habit that could be doing more harm than good. Speaking to The Mirror, she outlined exactly where people tend to go wrong and what they should be doing instead.
The biggest issue Nateri points to is the unintentional stacking of supplements that share the same active ingredients. Someone might be taking a multivitamin, an immune-boosting formula, and a standalone zinc or vitamin C supplement all at once without realizing the overlap. “One of the most common mistakes I see is people combining winter supplements that contain the same ingredients,” she warned. “You might be taking a multivitamin, an immune support product, and extra zinc or vitamin C and suddenly, without even realizing it, you’ve tripled your intake.”
The assumption that vitamins carry no real risk is something Nateri directly challenges. Just because a product is available over the counter does not mean it should be taken carelessly or in unlimited quantities. “People think vitamins carry no risk because they can be bought without a prescription,” she said plainly. “That simply isn’t true.” This misconception is particularly dangerous because it leads people to layer multiple products together, believing the worst that can happen is they spend a little extra money on supplements their body doesn’t need.
The specific risks vary depending on which vitamin or mineral is being overconsumed. Zinc is a good example of how a beneficial nutrient can backfire when taken in excess. Intakes higher than 9.5 mg per day for men and 7 mg per day for women can actually interfere with the body’s ability to absorb copper, and over time this can paradoxically weaken the very immune system people are trying to support. Vitamin D is another one to watch closely, as consuming more than 100 micrograms (4,000 IU) can push calcium levels in the blood to dangerous heights. And vitamin A, because it accumulates in the body’s tissues rather than being flushed out, poses a liver damage risk if the daily threshold of 1.5 mg is consistently exceeded.
Vitamin C gets a lot of attention as a seemingly harmless immune booster, but Nateri points out that the body’s ability to absorb it is actually limited. “When intake exceeds 200 mg per day, the body largely excretes the surplus,” she explained, noting that the recommended daily amount is just 40 mg. Flooding the system with high-dose vitamin C supplements, then, is largely a waste and not as protective as people assume. Beyond the specific nutrients, Nateri also highlighted that supplements can interfere with prescription medications in ways patients may not anticipate. Calcium, magnesium, iron, and high doses of vitamin C can all reduce how well the body absorbs antibiotics, thyroid medications, and certain blood pressure drugs. “If you’re taking any prescription medication, even short-term, always consult your doctor or pharmacist before starting supplements,” she advised.
When it comes to what is actually worth taking, Nateri does have some sensible suggestions. Vitamin D during the winter months is reasonable for most adults, given how little sunlight people get during that time of year. Omega-3 fatty acids containing EPA and DHA are worth considering for their role in supporting both brain and heart health. Magnesium can also be genuinely useful for people dealing with sleep difficulties or muscle tension. Her overarching message, though, is one of perspective: “Supplements should support your health, not replace quality sleep, a balanced diet, and medical advice. If you’re unsure, ask your pharmacist. You could avoid doing yourself more harm than good.”
It is worth understanding a bit more about how dietary supplements are regulated and why the confusion around them is so common. In the United States, supplements are regulated by the Food and Drug Administration (FDA) under the Dietary Supplement Health and Education Act of 1994, but they are not subject to the same rigorous approval process as prescription drugs before reaching store shelves. This means manufacturers are not required to prove their products are safe or effective before selling them to the public. Fat-soluble vitamins such as A, D, E, and K are stored in the body’s fatty tissues and liver, meaning they can accumulate to toxic levels far more easily than water-soluble vitamins like C and the B vitamins, which are generally excreted in urine when consumed in excess. The upper tolerable intake levels for vitamins and minerals are established by the National Academies of Sciences, Engineering, and Medicine and serve as a guide for how much is too much. Many popular immune-support blends on the market contain ingredients that overlap significantly with standard multivitamins, which is precisely the combination problem Nateri is warning against.
If you’ve ever wondered whether your supplement routine might be working against you, share your thoughts and experiences in the comments.
