Vitamin D - optimising your levels through Autumn and Winter

As we say goodbye to the summer sun, our vitamin D levels start to decline as we head into autumn and winter. If you had plenty of sun exposure over the summer, your levels of vitamin D may keep you going for a while, however due to indoor lifestyles, many of us don’t even get adequate exposure in the summer, meaning that by wintertime you may find that your levels decline down to a deficient or insufficient state. Approximately 1 in 5 people in the UK have deficient or insufficient vitamin D levels. From my experience in clinic, this is something that I see a lot of, regardless of the time of year.

Vitamin D3 (the active form of vitamin D) is obtained primarily from sunlight. Here in the UK, due to our latitude, we have about 6 months in every year where the sun isn’t strong enough to provide adequate vitamin D. Other factors that put you at risk of not getting enough vitamin D are having darker skin (which requires more sun exposure as skin pigmentation reduces vitamin D production in the skin), indoor lifestyles, sunblock and clothing coverage, and age.

The current guidance from Public Health England (PHE) is to have a dietary or supplemental intake of 400 IU (10 micrograms) a day to maintain adequate vitamin D levels (1) . This is hard to obtain from dietary sources alone. The main dietary sources are egg yolk and oily fish. However 1 large egg only provides around 40-45 IU. Fish provides greater amounts with salmon supplying around 525 IU per 100g, but this is not sustainable or healthy to have every day due to toxic pollutant levels in fish. Fortified breakfast cereals can also provide some vitamin D; however most are over-processed with added sugar making them a poor nutritional choice. This makes supplementation during the colder months a smart lifestyle choice.

Vitamin D plays many essential roles in the body, more of which are emerging all the time. It is important for healthy bones by helping the body to absorb calcium, regulating cell growth and proliferation (indicating a role in cancer prevention), mental health, cardiovascular health and regulating a proper immune function. As research progresses scientists are finding vitamin D receptors in more parts of the body such as the heart, muscles fibres, blood vessels and more, meaning vitamin D has an impact on all kinds of functions that are not yet fully understood. Research has found that even insufficient levels, which typically display no symptoms, can still play a part in contributing to chronic diseases such as cardiovascular disease, cancer and diabetes (2). Additionally, a recent article in the Lancet has suggested that vitamin D should be considered beneficial in both Covid-19 prevention and risk of severity, with supplementation providing people with little to lose but potentially much to gain (3).

It is always advisable to get your levels checked before supplementing with vitamin D, as you can have too much of a good thing and complications can occur from taking too much of it. A simple test can be done by your GP or nutritionist. If you are found to have a deficiency, or even just insufficient amounts, this can be easy to correct with the right supplementation, getting you back on track to your healthiest self.