Vitamin D overdose warning as expert reveals four symptoms of taking too much

 The NHS is urging millions of Brits to take vitamin D for their health, but an expert has cautioned that certain symptoms and side effects need to be monitored. It is advised to take the supplement over the darker winter months.

An NHS spokesperson wrote on X, formerly Twitter: "From October to March we can't make enough vitamin D from sunlight, so to keep bones and muscles healthy, it's best to take a daily 10 microgram supplement of vitamin D. You can get vitamin D from most pharmacies and retailers."

While experts agree that many people across the UK should be taking vitamin D supplements, especially during the winter, this advice comes with a significant caveat. Sunlight is crucial for vitamin D production as UVB rays from the sun trigger a chemical reaction in the skin.

This process converts 7-dehydrocholesterol into vitamin D3, which is vital for calcium absorption, bone health, and immune system support. The UK Government recommends that everyone should consider taking a daily vitamin D supplement of 10 micrograms (400 IU) throughout autumn and winter.

The sunlight in this period isn't strong enough for the body to produce sufficient vitamin D, and getting enough through diet alone can be difficult, reports the Mirror. But Tobias Mapulanga, biomedical scientist and co-founder of Repose Healthcare, has issued a warning about symptoms to watch for.

He said: "As the NHS encourages vitamin D in winter, many people are reaching for bottles in the darker months and accidentally overshooting, then blaming the fallout on seasonal bugs.

"When constant thirst and needing the loo more often; queasiness, tummy pain or constipation; headaches or brain fog; and new aches or cramps appear soon after increasing your intake or adding sprays or gummies, that points to a supplement backfiring."

He added: "The stakes are clear: the right amount supports you, but doubling up can turn a well-meant routine into feeling worse rather than better."

Research showed that 42 per cent of surveyed UK adults had taken vitamin D supplements within the previous 12 months, yet Which? found supplements, including vitamin D, being sold with doses up to 12.5 times the recommended safe upper limit.

NHS England recorded 42 reports over a two-year period of high‐strength vitamin D being administered more frequently than intended, with certain cases requiring hospital treatment for hypercalcaemia.