Several years ago, research revealed that three-quarters of all US teens and adults are deficient in Vitamin D, also known as the “Sunshine Vitamin” . This is possibly due to a combination of factors, such as increasingly sedentary lifestyles, an aging population and fear of sunburn or skin cancer.
Another factor which may be overlooked is the increase in statin (cholesterol-reducing) drugs. A certain amount of cholesterol is necessary, in order for sunlight to be converted into Vitamin C.
Deficiency is more common among the elderly, pregnant or breastfeeding mothers, people who cover up for religious or cultural reasons, and those with darker skin tone. The darker your skin, the more sun exposure required to produce adequate Vitamin D levels.
It is well-documented that adequate Vitamin D levels are required for healthy bones and teeth. This is because Vitamin D is needed for the body to utilize calcium. Healthy levels of Vitamin D, in this regard, is particularly important for growing children, and also the elderly, as adequate levels can help prevent bone fractures and breaks, resulting from falls.
It is also well-known that adequate Vitamin D is required for healthy immune function. In fact, lack of sunshine during the cooler months (which can last for six months of the year, or more, in some countries), may be at least part of the reason that winter is referred to as “flu season”. People become more prone to infection as their Vitamin D levels diminish, which doesn’t happen immediately, but accumulates over time, since Vitamin D is a fat-soluble vitamin.
A recent review found that Vitamin D could help prevent upper respiratory infections, such as pneumonia, bronchitis, etc. These findings were particularly pronounced in those who started out with lower levels .
While Vitamin D plays an important role in preventing infection, it may also play some kind of regulatory role in the immune system that prevents it from attacking its own cells. It has been revealed that lack of Vitamin D is a risk factor for developing auto-immune disease.
Vitamin D also seems to play a protective role in preventing cancer, including skin cancer, which is rather ironic.
Deficiency is a risk factor in seizure disorders, such as epilepsy. Unfortunately, some seizure medications tend to exacerbate deficiency, as they interfere with Vitamin D metabolism. It is recommended that people with seizure disorders or on seizure medications be tested for Vitamin D levels, and take corrective action if required.
Low levels of Vitamin D have been linked to mood disorders, such as seasonal affective disorder (SAD), also sometimes known as “winter blues”. Lack of natural light also affects serotonin levels, which also helps to regulate mood and sleep patterns. Many of us spend 23 out of 24 hours per day indoors. Indoor light is vastly different to light exposure outdoors, with indoor light providing about 100 units (lux) of light, while sunshine provides about 20,000 lux. Even an overcast day provides around 7000 lux of light.
Sunlight is the major precursor of Vitamin D, however small amounts are found in oily fish, and free-range eggs and milk.
Experts suggest that everyday exposure during summer will provide enough Vitamin D for the average person; however, we may need to make extra effort to take in sunshine during the cooler months.
 Lite J. Vitamin D deficiency soars in the US, study finds, Scientific American, https://www.scientificamerican.com/article/vitamin-d-deficiency-united-states/. Accessed 11th March, 2017.
 Martineau AR, Jolliffe DA, Hooper RL et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. The BMJ 2017;356:i6583