We all consider looking after our health and especially our immune system during the winter season. Vitamin D deficiency affects almost half of the population around the world. The biggest vitamin D source is direct sun light. At this time of year, not many people can make enough vitamin D in their body, because of climate change. Three months of the winter period, Britons can enjoy the sunlight only an hour or two a day. This is because the position of the United Kingdom, during these three months, is surrounded by heavy clouds. Therefore, the duration of the sunlight during the day get shortened. People, therefore, avoid spending time outside for physical activity. Vitamin D not only helps to protect our immune system against the viruses but also reduces the risk of heart disease, cancer, fractures, type-2 diabetes and depression. This is why we should consider getting the recommended amount of Vitamin D every day.

Sources of Vitamin D

The most effective source the human body can get vitamin D from is bright sun light, that gets into the skin and produces up to 25,000 IU source of vitamin D. Vitamin D produced by the sun is a better material source and also lasts twice as long. Every year the human body typically sees from 1000 to 1500 hours of the direct sun exposure, the rest of the year other sources of the this vitamin are available. In addition, it could be a person’s lifestyle such as less time spending outdoors, sitting inside the room with no direct light and may also depression can cause vitamin D deficiency [it may not be clear how depression can be linked to lack of vit D, can you make this more explicit?]. At this stage supplements are taken, which can help to boost the vitamin source to the body and meet the recommended average criteria.

What happens if there is never enough vitamin D?

The major cause of vitamin D deficiency is natural sun light. This is why it so important to spend more time outdoors, especially for children because vitamin D deficiency can lead to bone deformities such as rickets. During the summer holidays, the majority of people exercise outside, get tanned whilst lying on the beach or spend time in the park. This time of the year is the best opportunity to gain the organic source of vitamin D. People who use sunscreen with sun protection factor of 30, reduces vitamin D synthesis in the skin by more than 95%. This happens because the sunscreen works as a blockage of synthesis and it reduces risk of cancer. Cancer is the main reason people are alarmed to use this type of protection when exposed to direct sunlight. Those with dark skin have higher levels of the pigment melanin. This makes it harder to generate vitamin D from sunlight as the pigment reduces the ability to do so. Those with darker skin would be recommended to build up their daily requirements from food and supplement sources.


There are only a few vitamin D food sources. The second best vitamin sources after the sun is supplementation. Currently, a variety of vitamin D supplements are available to the public but not many of them have more than 800 IU. Cod liver oil is the best source of vitamin that could be found but it also may be dangerous because of vitamin A toxicity. There is a recommended vitamin D intake criteria that many people use for guidelines to uptrain their vitamin D levels in the blood. Children from the early months up to teenager years are recommended to take 1000IU a day. Whilst adults from 19 to 50 years old and over are recommended to get almost double.


Vitamin D contains many clinical benefits. The main reason why vitamin D is so important to our daily requirements is because it decreases cell proliferation and increases cell differentiation which also reduces the risk of the colorectal and breast cancers, and improves the prognosis of those who diagnosed with the lung cancer. In other words, vitamin D prevents the growth of new blood vessels (angiogenesis) which prevents the pathological processes such as tumour growth, metastasis, obesity and non-alcoholic fatty liver disease. Vitamin D has anti-inflammatory effects that reduces inflammation to the biological responses to the injury or infection. Those effects could be reducing the swelling, redness and tenderness. Many studies have shown that individuals with low levels of vitamin D increases their risk of cancer, whilst in people with higher levels of this vitamin source, it can actually help to reduce this risk. During the winter period vitamin D is especially important to fight the disease, boosts weight loss and also to reduce depression.