A prescribing pharmacist has issued a stark health warning to the British public, cautioning that many individuals could be unknowingly putting themselves at risk by "over-stacking" dietary supplements on a daily basis. The expert emphasises that while the intention behind taking vitamins and minerals is typically positive, improper use can lead to unintended harmful consequences.
The Growing Concern Over Supplement Misuse
Hanna Yusuf, a prescribing pharmacist at Chemist4U, has raised significant concerns about how Brits are consuming supplements. She explains that while vitamins and minerals are essential for optimal bodily function, and a balanced diet should ideally provide all necessary nutrients, supplementation has become increasingly popular. However, this trend comes with considerable risks if not managed correctly.
"The intention behind supplements is usually good, but the execution often isn't," Yusuf stated. "We regularly see people unintentionally doubling up on vitamin D, taking high-dose vitamin C powders daily, or supplementing magnesium 'just in case'. Some supplements can cause side effects, interact with medicines, or mask underlying issues. If you don't actually need them, they can be unnecessary at best, and harmful at worst."
Common Supplements and Their Overlooked Risks
Yusuf has detailed specific risks associated with several widely used supplements, urging the public to exercise greater caution and seek professional advice.
Vitamin D: The Accidental Overdose Risk
While the NHS recommends vitamin D supplementation from October to March to support mood, immunity, and energy during darker months, Yusuf warns of potential dangers. "Too much over time can raise calcium levels, which may cause nausea, confusion, kidney strain and, in severe cases, kidney damage," she explained. "The biggest issue is accidental doubling up via multivitamins and standalone vitamin D and immunity products."
Her advice is to adhere strictly to recommended daily guidance for most adults, typically 10 micrograms or 400 IU in winter, and avoid stacking products containing vitamin D unless specifically advised by a clinician. Extra caution is necessary for individuals with kidney disease, sarcoidosis, hyperparathyroidism, or a history of kidney stones.
Iron: The Unnecessary Supplement
Often taken for fatigue, low energy, and hair loss, iron supplementation can be particularly problematic. "Iron is one of the easiest supplements to take unnecessarily," Yusuf noted. "Excess iron can cause stomach pain, constipation, worsen nausea, and in some cases contribute to iron overload, especially in people with haemochromatosis. It can also interfere with absorption of other medicines, and some medicines can reduce iron absorption."
She strongly advises against self-prescribing iron for tiredness, recommending a blood test first. If supplementation is advised, careful adherence to dosing guidance and timing instructions is crucial, with some people tolerating alternate-day dosing better than daily intake.
Omega-3: Quality and Interaction Concerns
Popular for heart health, inflammation reduction, and brain function support, omega-3 supplements carry their own risks. "Can increase bruising and bleeding tendency in some people, especially at higher doses or alongside blood thinners or antiplatelets, and can cause reflux burps or stomach upset," Yusuf said. "Quality and dose vary widely between products."
Her recommendation is to prioritise oily fish in the diet where possible. If supplementing, choose a reputable product with clear EPA and DHA amounts, and consult a pharmacist or GP if taking anticoagulants, antiplatelets, or planning surgery.
Magnesium: Digestive and Kidney Risks
Yusuf highlighted that magnesium supplements "can cause diarrhoea and low blood pressure at higher doses, plus there's higher risk in kidney disease due to reduced ability to clear magnesium. Some forms are more likely to upset digestion."
She advocates a "food first" approach, suggesting nuts, seeds, leafy greens, and wholegrains. If supplementing, start with low doses, avoid stacking with 'relaxation' blends that also contain magnesium, and seek advice if kidney issues are present.
Vitamin C: Not a Cure-All
Frequently taken to boost immunity, vitamin C supplements require careful management. "High doses can cause diarrhoea and stomach upset, and in some people it may increase kidney stone risk," Yusuf cautioned. "Also, it doesn't cancel out poor sleep, diet or stress. Aim for food sources first like citrus, berries, peppers, and broccoli. If supplementing, avoid mega-doses as a daily habit."
Zinc: Short-Term Use Advised
Regarding zinc supplementation, Yusuf added: "Nausea and stomach pain are common with higher doses; long-term high intake can interfere with copper absorption and contribute to deficiency. Use short-term only if appropriate, don't stack multiple zinc-containing products, and avoid long-term high-dose use unless advised."
Prioritising Safety and Professional Guidance
Yusuf's overarching message is clear: "When it comes to supplements, simplicity and consistency is usually safer and more effective than stacking multiple products." She urges Brits to ensure they follow instructions either on the bottle or from their GP, and to consult healthcare professionals before starting or combining supplements. This approach helps mitigate risks of side effects, medicine interactions, and potential masking of underlying health issues, ensuring supplementation supports rather than compromises wellbeing.
