People have been warned not to take too much (Image: Getty)
The late Dr Michael Mosley highlighted vitamin D as an important nutrient that may support mental health and help protect against dementia.
On BBC Radio 4’s Just One Thing with Michael Mosley, he explained that vitamin D may help protect the brain. He also noted that in the UK, sunlight levels in winter are too low to produce enough vitamin D naturally, saying: “In the winter, I take this tiny little pill every day.”
He added: “Taking this cheap, little supplement could bolster your immune system, making you less likely to catch a cold. And there is mounting evidence that in high doses it may even protect you from cognitive decline and dementia.”
Mosley revealed that “since its discovery in the 1920s, vitamin D’s best-known role is keeping bones healthy by increasing our body’s absorption of calcium. That’s why rickets, which used to be very common, is rare now”.
Mosley made an exception for the supplement, explaining: “Now, I don’t normally recommend supplements on Just One Thing, but for vitamin D, I am making an exception.”
He explained that while many know it’s great for our bones, studies show it’s better for us than we think. Mosley noted that “scientists have discovered vitamin D receptors in nearly all the cells of our body, suggesting that its health benefits extend far beyond bones”.
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Vitamin D and dementia
On its website, the BBC reported that Dr David Llewellyn from the University of Exeter analysed a large US study that followed over 1,600 people. It found that those with vitamin D deficiency were more than 50% more likely to develop Alzheimer’s or dementia. In people with severe deficiency, the risk was more than doubled – about 125% higher.
Llewellyn said: “It was the first compelling evidence to link low levels of vitamin D in the blood to an increased risk of dementia.”
Speaking about the link between the vitamin and brain health, the university Professor notes that it appears to interact with the hallmarks of Alzheimer’s disease with the BBC noting it can “chop up abnormal proteins that form in the brain, such as amyloid plaques and tau, and clearing them.
“Other scientists have argued that it also helps to protect the blood supply to the brain and reduce inflammation,” says Llewellyn, “and that might be helpful with other types of dementia like vascular dementia.”
Do I get enough vitamin D from the sun?
In the UK during winter, there isn’t enough sunlight for most people to make adequate vitamin D. In spring and summer, the skin can produce vitamin D from sunlight, but in winter the sunlight is too weak and limited. As a result, vitamin D deficiency is common and may have a greater impact on health than previously understood, according to Llewellyn.
Some groups of people are at even higher risk of vitamin D deficiency, so it becomes a greater health concern for them. “If you have dark skin you don’t produce as much vitamin D from exposure to the same amount of UV radiation,” explains Llewellyn. In the UK, over 50% of people of South Asian descent are actually deficient in vitamin D during the winter months.
On top of this, vitamin D deficiency gets more common with age as our skin becomes less efficient at producing vitamin D: “More than half of older adults are below the threshold for deficiency,” he added.
How much vitamin D do I need?
The NHS says as “it’s difficult for people to get enough vitamin D from food alone, everyone (including pregnant and breastfeeding women)”, many people “should consider taking a daily supplement containing 10 micrograms of vitamin D during the autumn and winter.”
It adds: “Between late March or early April to the end of September, most people can make all the vitamin D they need through sunlight on their skin and from a balanced diet. You may choose not to take a vitamin D supplement during these months.”
It further warns: “If you choose to take vitamin D supplements, 10 micrograms a day will be enough for most people. Do not take more than 100 micrograms (4,000 IU) of vitamin D a day as it could be harmful. This applies to adults, including pregnant and breastfeeding women and the elderly, and children aged 11 to 17 years.”