Doctor urges Britons to start taking vitamin D as sunlight wanes
GP warns about seasonal drop in sunshine, says around one in six adults are deficient and urges supplements to protect bones, muscles and immunity
As daylight hours shrink and autumn weather arrives, a GP is urging people across Britain to begin taking vitamin D supplements to avoid seasonal deficiency and protect bone, muscle and immune health.
Dr. Donald Grant, a general practitioner and senior clinical adviser at The Independent Pharmacy, said the reduced sunlight in the coming months means "our bodies will no longer be able to naturally create enough vitamin D." He warned that deficiency increases the risk of conditions such as rickets and osteoporosis and can contribute to muscle weakness and a higher risk of falls in older people.
Vitamin D helps the body absorb calcium and plays a role in normal muscle and immune function, Dr. Grant said. He noted that natural dietary sources include oily fish, red meat and egg yolks, but added that the vitamin is primarily produced by the skin after exposure to sunlight — a process that becomes less effective as the UK moves into darker months.
Public-health measurements of adequate vitamin D vary. The institute of medicine in the United States sets a minimum threshold at about 20 nanograms per millilitre, while the NHS cites 12 ng/ml as a healthy base level. It is currently estimated, Dr. Grant said, that around one in six adults in the UK do not get enough vitamin D, with older people needing particular attention.
The NHS recommends 400 IU of vitamin D per day for many people. Dr. Grant said he believes supplements that provide more than this minimum can offer stronger support for immune, bone and muscle functions as the weather darkens. He advised that people seek medical advice from their GP before adding supplements, particularly if they have an existing health diagnosis.
Medical guidance notes that excessive vitamin D can cause the body to absorb more calcium than it needs, leading to calcium accumulation in the bloodstream and deposition in tissues such as the kidneys, lungs and heart. Symptoms associated with too much vitamin D or resultant high calcium levels can include nausea, vomiting, constipation, dehydration, bone pain and kidney stones.
Research has also explored vitamin D's relationship with inflammatory conditions. A 2017 study led by researchers at the University of Birmingham suggested maintaining sufficient vitamin D levels might help prevent the onset of inflammatory diseases such as rheumatoid arthritis. Study author Dr. Louisa Jeffery said the findings indicated that while vitamin D may contribute to prevention, patients who already have rheumatoid arthritis may not gain the same benefit at standard doses and could require higher amounts.
Health authorities and clinicians continue to recommend that people consider seasonal supplementation where appropriate, especially during months with limited sunlight. Those who are pregnant, elderly, housebound, have darker skin, or have conditions that affect vitamin absorption have been identified in previous public-health advice as groups that may be at higher risk of deficiency, and are often urged to discuss supplementation with their GP.
Dr. Grant said starting supplements earlier in the autumn can "combat the lack of sunlight, avoiding the risk of nutrient deficiencies throughout the colder period," but reiterated the importance of personalised medical advice to balance benefits and risks.
Anyone considering a change in supplementation is advised to consult their GP or a qualified healthcare professional to determine an appropriate dose and to rule out potential interactions with existing medications.