Vitamin D is not a vitamin, but actually, a hormone produced by the body. It is one of the immune system’s champion fighters. Modulating both innate and acquired immunity, it helps to activate the T cell response to infections and has been shown to reduce the risk of developing respiratory tract and autoimmune conditions. The sun plays an important role in the body’s synthesis of vitamin D during spring and summer.
This is why vitamin D deficiencies are often seasonal, as reduced exposure to sunlight during the darker months typically results in commonplace illnesses like colds and flu. The body synthesises 90% of its vitamin D from contact with direct sunlight, although from September to early April this is hugely reduced for those who live in countries like the UK, so it’s a good idea to take a supplement. Not only can vitamin D help support the immune system, it can also contribute to reducing inflammation in the airways.
In fact, low levels of vitamin D can increase the risk of having an asthma attack. Vitamin D is essential for heart and lung health and while the sun is its most powerful source, supplements are a really easy way to keep levels topped up during winter, particularly between October and March.