Is taking a stack of supplements at the same time dangerous?
Whether a supplement stack is smart or dangerous depends on which substances you combine and whether you also take medicines. Always tell your doctor or pharmacist what you are taking, and be especially careful with St John's wort and goldenseal.
The biggest risk of a supplement stack lies not in the pills themselves, but in combinations with prescription medicines. Nearly a quarter of American adults combine prescription drugs with supplements. Most people do not mention this to their doctor or pharmacist, which means problems are easily missed.
Not every supplement carries the same risk. St John's wort and goldenseal cause demonstrable, clinically relevant interactions. If you take prescription medicines, avoid those two. Substances such as curcumin, garlic or green tea extract can sometimes cause problems, but that evidence comes largely from studies in cells and has rarely been confirmed in people. Supplements such as ginkgo, valerian and cranberry have little chance of interactions and are probably safe to combine for most people.
Sometimes a combination is actually worthwhile. Children receiving antibiotics are less likely to develop diarrhoea if they also take probiotics at a high dose (at least 5 billion live bacteria per day): the risk drops from 23% to 8%. Across 24 studies involving more than 4,400 children, no serious side effects were found. In severely ill or children with weakened immune systems, greater risk has been reported outside those studies, so caution is warranted in those cases.
Want to keep your muscles strong later in life? There is preliminary evidence in older adults for substances such as MitoQ, urolithin A, omega-3 fatty acids and the combination of glycine plus N-acetylcysteine. However, the studies are small, we do not know whether these substances are safe over the long term, and several researchers who assessed this work received funding from supplement manufacturers. NAD+ supplements (a substance that helps cells produce energy) are often promoted as beneficial for muscles, but research shows that any possible effects on movement do not come from improved energy production in muscle cells. The reason manufacturers give therefore does not hold up.
The practical lesson: if you take prescription medicines, always tell your doctor or pharmacist which supplements you are also taking. A broad stack taken without a specific reason offers no proven benefit for most healthy people, while the risk of interactions is real. Targeted use, based on a specific complaint or deficiency, has more backing than swallowing a handful of pills all at once as a precaution.
All claims are drawn from three publications: a narrative review on interactions between supplements and medicines, a combined analysis of studies on probiotics in children during antibiotic treatment, and a review on muscle-supporting supplements in older adults with reported conflicts of interest. No large independent studies are available on taking a broad supplement stack as a whole.
Does taking iron help, or is it actually a risk?
Taking iron clearly helps if you have a deficiency or anaemia, but is pointless and potentially risky if that is not the case. Have your iron levels checked before starting supplements.
Which supplements are best avoided when taking blood thinners?
Ginkgo biloba, ginger, garlic, cranberry and St John's wort are best known as risky combinations with warfarin and similar blood thinners. Tell your doctor or pharmacist which supplements you use, because even seemingly harmless products can affect the balance of blood clotting.
Which supplements or medications are best not combined with NAD+?
The combination of NAD+ supplements, particularly nicotinamide, with platinum-based chemotherapy is the most concrete reason for caution. For other interactions the indications are preliminary, but worth discussing if you use multiple substances.
Is spermidine from food just as good as a supplement?
There is no evidence that a spermidine supplement does the same thing as spermidine from food; supplements may be neutralised by the body and the effective dose in humans is unknown. If you want to increase your spermidine intake, opt for spermidine-rich foods.
Which supplements are worthwhile after forty?
A few supplements have reasonably solid backing after forty: calcium plus vitamin D for bone protection, B vitamins and a daily multivitamin for cognitive maintenance, and adequate protein for muscle preservation. Collagen is worthwhile for skin.
Is colostrum (beestings) a worthwhile supplement?
For now, colostrum has the strongest indications as an aid against respiratory tract infections in athletes; for most other claims the evidence is too thin or too contradictory to recommend anything.