The Scientific Advisory Committee on Nutrition (SACN) today published new recommendations that everyone should consume 10micrograms of vitamin D daily, the equivalent of about 400 International Units (IU).
The main way we get vitamin D is through our bodies synthesising it on exposure to sunlight, but it can also be taken in through diet – eggs, oily fish, and fortified foods such as cereals, are all good sources, although it’s not considered possible to get sufficient vitamin D from diet alone. For this reason, there were concerns that the general population had low vitamin D levels, especially in winter when sunlight is limited, prompting the Department of Health the ask SACN to review the evidence.
Dan Lock, a postgraduate student studying vitamin D and gut health at the Institute of Food Research, has produced this blog article in response to the new recommendations.
“This recent update from PHE regarding minimum daily vitamin D intake is evidence-based, well referenced, and seems pertinent in light of the prevailing consensus amongst vitamin D researchers; that poorer health outcomes are associated with reduced circulating levels of vitamin D.
It is previously established that vitamin D directly promotes bone health and muscle function throughout life, which is particularly important in early years, and in later life when the ability of the skin to synthesise vitamin D wanes (compounded by the fact that many older people are less active and so experience less direct sunlight).
Furthermore, when we look at large swathes of the population, it is also apparent that insufficient levels of vitamin D are associated with small increases in the chances of developing other diseases, affecting bowel health, the immune system, and cognitive function.
What is not yet well established, is if these associations are a direct result of having low vitamin D, or if there are other dormant heath conditions (such as a poor diet or exercise regime) that indirectly cause vitamin D levels to drop, whilst at the same time precipitating a decline in general health. Importantly, there’s little harm to be done by addressing both lifestyle factors and vitamin D insufficiency simultaneously.
Previous recommendations were probably conservative in light of recent advances in our understanding of vitamin D, particularly for at-risk groups and during the winter months, and it’s also true that serious complications from vitamin D supplementation are negligible at the minimum levels suggested by these new guidelines.
(It’s worth noting that clinical vitamin D deficiency and vitamin D insufficiency are two different things, the latter having no immediate consequence for health – these new guidelines are certainly no cause for alarm; the majority of adults in the UK are rarely clinically deficient, perhaps more, intermittently experiencing insufficient levels of vitamin D (especially those with darker skin or during the winter months). Equally, circulating vitamin D is relatively stable, which means if you were supplementing and happened to miss a day by mistake, there’d be no need for concern of either short or long-term consequences.
Anyone considering long-term supplementation is well advised to consult their GP first; vitamin D is processed by the liver and the kidneys, and so some people with underlying heath conditions might be more prone to undesirable side effects involving these organs”.
Dan Lock MRSB