Experts warn Brits to take vitamin D now as sunlight fades and winter health risks grow

Summer has ended abruptly in the UK, with dark skies and relentless rain replacing weeks of sunshine. But the gloomy weather brings more than just a dampened mood. According to health experts, it could leave millions at risk of a serious deficiency that impacts bones, muscles, and the immune system.

Dr Donald Grant, GP and senior clinical advisor at The Independent Pharmacy, has warned that the sudden loss of sunlight threatens the nation’s levels of vitamin D, a vital nutrient that the body mainly produces through direct sun exposure. As daylight hours shrink heading into autumn and winter, he says many people will struggle to get enough of it naturally.

“Vitamin D is primarily produced through direct sunlight, and as we head into the colder, less sunny months, many people will struggle to get enough,” Dr Grant explained. He emphasised that the vitamin plays a crucial role in several areas of health, from strengthening bones to keeping infections at bay.

Vitamin D helps the body absorb calcium, which is critical for bone strength and protection against conditions such as osteoporosis and rickets. It also supports the immune system, which is especially important during the colder months when colds, flu, and other viruses circulate more widely. On top of that, vitamin D contributes to muscle function, and deficiencies can increase the risk of weakness and falls, particularly among older adults.

“Like any essential nutrient, vitamin D supports the body in a number of ways,” Dr Grant said. “While most vitamins can be obtained from a balanced diet, vitamin D is the exception because it relies heavily on sunlight. That’s why supplements are such a valuable option at this time of year.”

The warning comes as supermarkets, pharmacies, and online retailers all report strong availability of vitamin D tablets, which cost as little as a few pounds. Dr Grant recommends that people start supplementing now, before levels drop too low, to ensure they are protected as the winter months take hold.

Although foods such as oily fish, red meat, and egg yolks can provide some natural vitamin D, diet alone is rarely enough to meet the body’s needs during the UK’s long, dark winters. For most people, supplements are the most reliable way to maintain healthy levels throughout the season.

The advice reflects government guidelines that already recommend vitamin D supplementation, particularly for vulnerable groups. During the summer months, the body is usually able to make sufficient amounts from sunlight, but once September arrives, the risk of deficiency begins to rise sharply.

For Dr Grant, the message is clear: it is not worth waiting until health problems appear. “With the weather remaining unsettled, it’s important to stay on top of your nutrient intake,” he said. “Taking vitamin D now will help protect your health through the months ahead.”

The call is timely. Research consistently shows that vitamin D deficiency is widespread in the UK, particularly during winter, and can have long-term consequences. As infections rise and immunity becomes more critical, experts say that topping up levels with a daily tablet could be the simplest and most effective step people can take to safeguard their health.

As the country braces for the colder, darker days, health professionals hope the public will take the warning seriously. A small daily pill, they argue, could make the difference between entering winter strong or vulnerable to a host of preventable problems.