Australian researchers have found a direct link between vitamin D deficiency and dementia.

Dementia is a chronic condition that affects cognitive functions and is doomed to worsen over time. It is also a common condition; It is estimated that 55 million people worldwide suffer from dementia. And millions of new cases are added every year. However, a considerable number of these can be prevented, researchers now say in the magazine American Journal of Clinical Nutrition† And in a fairly simple way too. Namely by taking extra vitamin D.

From suspicion to confirmation

In their research article, the scientists write that they have found a direct link between a deficiency of vitamin D and dementia. “Vitamin D is both a nutrient and a prohormone and we know there are still many situations where people don’t get enough vitamin D,” said researcher Elina Hyppönen. Scientias.nl† It has been suspected for some time that this can also have an effect on the chance that people will have to deal with dementia. “Vitamin D receptors can also be found in the human brain and we have long suspected that this may have implications for the development of cognitive disorders, such as dementia.”

To confirm that suspicion, Hyppönen and colleagues looked at data from nearly 300,000 Britons who participated in a long-term biobank study that aims to find out the extent to which genetic predisposition and environmental factors influence the development of a variety of diseases and conditions. “We know that some people always have slightly lower vitamin D levels than others in the same situation,” Hyppönen explains Scientias.nl from. “And that’s simply because of their genes. In this study, we grouped the subjects who, based on their genes, had a lower vitamin D content, versus the subjects who had more vitamin D based on their genes.” And then it was determined for each group how many people had actually developed dementia and how great the risk of dementia was for each of these groups. “If vitamin D really has an effect on the risk of dementia, then you should find evidence for it in this genetic analysis and that’s exactly what we did.”

Shortage

“We were also able to investigate how the genetic advantage of people who always have slightly more vitamin D than others in a comparable situation, is related to the risk of dementia if the vitamin D concentrations are really very low. The results of that analysis are particularly exciting, as we show that the effect of vitamin D on dementia risk is much stronger and may even be limited to people with very low levels of vitamin D. It suggests that attempts to increase the vitamin D levels to boost concentration, only help if you really have a deficiency.”

Effect on the brain

Hyppönen and colleagues also have ideas about how such a vitamin D deficiency increases the risk of dementia. “There are several ways in which vitamin D can affect the brain. First of all, the presence of vitamin D receptors in the hypothalamus suggests that the vitamin has a neurosteroid function and promotes the growth and maturation of the neurons. Secondly, vascular mechanisms may also play a role, as active vitamin D is associated with a lower risk of thrombosis and regulation of blood pressure. Third, vitamin D may keep the brain healthy by limiting neurovascular damage from inflammation and also curb amyloid proteins, which are commonly seen in Alzheimer’s.”

Preventing dementia

The findings of Hyppönen and colleagues are particularly relevant for countries and regions where vitamin D deficiency is prevalent. Because – with the help of simple supplements – there is still a lot to gain. “For example, in the UK population we observed, up to 17 percent of dementia cases could have been prevented by raising vitamin D levels to normal levels.”

Of course, dementia is a fairly complex condition, and there are many other factors that influence the likelihood of a person developing the disease. “A healthy lifestyle, with reasonable amounts of exercise, a healthy diet and maintenance of a normal weight also help. Just like making sure you are mentally challenged.” But vitamin D also plays a role. “When it comes to vitamin D, the most important thing is to avoid developing a deficiency. In situations where access to sunlight-induced vitamin D production is limited – as is the case for many people who live in nursing homes, for example – this can be difficult and contribute to their risk of dementia.” It certainly does not mean that these people need a huge dose of vitamin D, Hyppönen emphasizes. “Just the supplements you can get at the drugstore. And in my opinion, consideration should be given to standard, moderate vitamin D supplements for elderly living in nursing homes.”

A shortage?
How do you know if you have a vitamin D deficiency? If it is an extreme shortage, you can definitely notice that. You may then develop symptoms such as fatigue, muscle aches, bleeding gums, weaker bones or joint pain. But a limited deficiency is a lot more difficult to determine, because it gives no or hardly any symptoms. “There is a simple blood test that can determine the vitamin D level,” says Hyppönen. In people younger than 70 years, the vitamin D content should be 30 nano-mol per liter or higher. For people older than 70 years that is 50 nano-mol per liter or higher.

Vitamin D is a well-known and much-discussed vitamin, which was also frequently discussed during the pandemic, for example. Hyppönen is aware of this and hopes that her study will provide some direction in the discussions that are being held about the vitamin. “There is a lot of controversy about the health effects of vitamin D,” she says. “It ranges from extreme optimism, seeing the vitamin as a life-saver, to complete write-off of any importance this vitamin may have to health. Our study provides context to evidence previously collected on this vitamin and shows that – as you might reasonably expect – a lack of vitamin D is clearly harmful, including for brain health.” That said, that’s certainly no reason to run to the drugstore and stock up on supplements right now. “Most of us are probably okay,” Hyppönen emphasizes. “And there’s no reason to overdo it and aim for a really high vitamin D level, because there’s probably little benefit.” So also for the vitamin D content: act normal. Then your health will benefit.

“But for anyone who for some reason doesn’t make enough vitamin D from sunlight, dietary changes may not be enough and supplements may be necessary,” Hyppönen said. And in that scenario, the supplements can make a big difference. “Dementia is a progressive and debilitating disease that destroys individuals and their families. If we can change that reality by making sure none of us are severely deficient in vitamin D, it could (…) improve the health and well-being of thousands.”