ITV regular guest Dr Amir Khan shared a "dangerous" warning to millions of Good Morning Britain (GMB) viewers on Friday. The full-time NHS GP appeared live on the show via videolink to discuss vitamin and mineral supplements.

It comes after experts at Which? found supplements containing huge doses being sold on online marketplaces. Which? looked at Vitamin D, Vitamin A, Vitamin B6 and Zinc supplements listed for sale on popular platforms, and Dr Amir Khanhas warned some online brands "have dangerously high levels of vitamins and minerals in".

He continued: "Lots of people think when it comes to vitamins and minerals, more is better, but actually too much can cause harm.

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"Vitamin D is a good example, we should all be taking a vitamin D supplement between the months of October and April because there just isn't enough sunlight here in the UK for our skin to make it. But the NHS recommends 10 micrograms per day of vitamin D, now we can probably tolerate up to 100 micrograms per day of vitamin D, but what we're finding in some of these brands is that there's up to 1,250 micrograms - that's huge dosage.

"Remember vitamin D helps you absorb calcium from your food, but too much calcium can cause problems with your kidney and your heart."

The doctor went on to say that too much vitamin A can cause liver toxicity, too much vitamin B6 can affect your nerves and too much zinc, which many people take for colds, can affect how you absorb iron. This can led to anaemia, and can affect your copper absorption, too.

Dr Amir added: "The problem we have is a lot of these online or imported brands aren't regulated, labels can be misleading, and there's a social media trend right now called 'megadosing' encouraging people to take huge doses of vitamins and minerals, which is really harmful.

"My advice is always stick to a recommended or known brand, or get your supplements from a pharmacy. Stick to the NHS recommended doses, or the ones prescribed by your doctor, and if you're unsure your community pharmacist is a really good person to speak to."