Here’s what you need to know about the potential side effects of certain supplements
An expert warned of some risks when taking supplements(Image: Getty)
A pharmacist has issued a health warning, claiming you could be “over-stacking” your supplements. You may not realise that certain dietary supplements can’t be taken together or doubled up.
Many of us are aware that vitamins and minerals are required to help keep the body functioning at its best. While we should be able to get everything we need through a healthy, balanced diet, this isn’t possible for everyone.
Therefore, taking supplements is a popular way to ensure you’re not missing anything. But you must ensure you follow instructions, either on the bottle or from your GP, to take them correctly.
Hanna Yusuf, prescribing pharmacist at Chemist4U, warned that you could be leaving yourself vulnerable to side effects and other problems. “The intention behind supplements is usually good, but the execution often isn’t,” she said.
“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.”
She added: “When it comes to supplements, simplicity and consistency is usually safer and more effective than stacking multiple products.” Hanna then shared some of the most commonly used supplements, the risks people overlook, and how to take them more safely.
You must ensure you follow instructions, either on the bottle or from your GP, to take them correctly(Image: Getty)
Vitamin D
The NHS recommends that Brits take vitamin D from October to March. This supplement can help boost mood, immunity, energy in the darker months
But Hanna warned of the risks people can miss: “Too much over time can raise calcium levels, which may cause nausea, confusion, kidney strain and (in severe cases) kidney damage. The biggest issue is accidental doubling up via multivitamins and standalone vitamin D and immunity products.”
She therefore advised you stick to recommended daily guidance for most adults (often 10 micrograms / 400 IU in winter) and avoid stacking products containing vitamin D unless advised by a clinician. You should take extra caution if you have kidney disease, sarcoidosis, hyperparathyroidism, or a history of kidney stones.
Iron
People take iron for fatigue, low energy, and hair loss. “Iron is one of the easiest supplements to take unnecessarily and excess iron can cause stomach pain/constipation, worsen nausea, and in some cases contribute to iron overload (especially in people with haemochromatosis),” Hanna said. “It can also interfere with absorption of other medicines, and some medicines can reduce iron absorption.”
She said: “Don’t self-prescribe iron for tiredness. Get a blood test first and if advised to take it, follow dosing guidance and timing instructions carefully (some people tolerate alternate-day dosing better than daily).”
High doses of vitamin C can cause diarrhoea and stomach upset(Image: Getty)
Omega-3
Many people take omega-3 for heart health, inflammation, and brain health. “Can increase bruising/bleeding tendency in some people (especially at higher doses or alongside blood thinners/antiplatelets) and can cause reflux burps or stomach upset,” Hanna said. “Quality and dose vary widely between products.”
She advised: “Prioritise oily fish in the diet where possible; if supplementing, choose a reputable product with clear EPA/DHA amounts, and speak to a pharmacist or GP if you’re on anticoagulants/antiplatelets or have surgery planned. “
Magnesium
Hanna said: “Can cause diarrhoea and low blood pressure at higher doses, plus there’s higher risk in kidney disease (reduced ability to clear magnesium). Some forms are more likely to upset digestion.”
Instead, she recommended: “Food first (nuts, seeds, leafy greens, wholegrains). If supplementing, start low, avoid stacking with ‘relaxation’ blends that also include magnesium, and get advice if you have kidney issues. “
Vitamin C
People often take vitamin C supplements to boost their immunity. But Hanna said: “High doses can cause diarrhoea and stomach upset and in some people it may increase kidney stone risk.
“Also, it doesn’t cancel out poor sleep, diet or stress. Aim for food sources first (citrus, berries, peppers, broccoli). If supplementing, avoid mega-doses as a daily habit.”
Zinc
Hanna 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.”