The Healthy Food Guide team believe that making small diet and lifestyle changes brings the best long-term gains. We look at the science behind the headlines and promote a balanced way of eating.

Some studies have linked a lack of this essential vitamin to Seasonal Affective Disorder


Vitamin D is made in the body when the skin is exposed to UVB rays from sunlight. But in autumn and winter, when our skin is exposed to little sunlight and weak rays, we make far less of it. Studies show during winter and spring, when we’ve gone for several months with little sunlight, we’re more likely to have extremely low levels of vitamin D in our blood than in summer and autumn.

Can a lack of vitamin D affect your mood?
There’s much debate about whether this lack of vitamin D affects our mood and results in depression. Research does show vitamin D has an important role to play in the brain – receptors for the vitamin have been found in many parts of the brain, including the areas linked to depression – but exactly how it works isn’t fully understood. One theory is a lack of vitamin D results in lower levels of mood-enhancing serotonin, which makes us more prone to depression.

Indeed, studies confirm a connection between low levels of vitamin D in the blood and an increased risk of depression. But a recent review of the research, published in The British Journal of Psychiatry, confirmed it’s unclear whether a deficiency in fact causes depression or whether low vitamin D levels are the result of being depressed. Being such a new area of research, we can’t draw any firm conclusions – but we do know vitamin D is essential for good health, so if we’re not getting it from sunlight, we need to eat more vitamin D-rich food or consider a supplement.

So should you take a vitamin D supplement?
There’s no firm evidence to show taking a vitamin D supplement will help treat or prevent Seasonal Affective Disorder, but it’s unlikely to cause any harm or make your symptoms worse (although you might not see an improvement, either).

For adults under the age of 65 and children over the age of three, there are currently no UK guidelines as to how much vitamin D we should have each day. However, the World Health Organization recommends 15mcg for over 65s, 10mcg for 51 to 65-year-olds and 5mcg daily for everyone under the age of 50 (the latter is what appears as the RDA on food labels).

In the UK, the Department of Health advises pregnant and breastfeeding women, adults over 65 and people who aren’t exposed to much sunlight to take a daily 10mcg supplement of vitamin D – and that would seem to be a good amount to take. (It’s wise, however, to avoid any supplements containing more than 25mcg vitamin D a day, as this could cause health problems).

Eat more vitamin D-rich foods, too. The best sources are oil-rich fish and eggs, with smaller amounts in meat. Margarines have to be fortified by law, but many cereals, yogurts and soya milks also have added vitamin D.