In the dark midwinter

Few people in the world get a darker winter than the one we experience in the UK. We are so far from the equator that the sun for several months of the year has hardly any power in it at all. And as we approach Christmas, it just about gets above the horizon at midday. Unless you live in Northern Russia, one of the barely-populated regions of Canada, Greenland, Alaska or the Nordic countries (or you are stationed in Antarctica), you get a brighter winter than we do here in mainland Britain.

There is more and more acknowledgement of the effects of weak sun on our mental state. Seasonal affective disorder (SAD) is now recognised as a genuine condition, and "SAD lamps" are doing great business this winter.

Meanwhile, anyone who's done biology at school can tell you that a lack of vitamin D, which our bodies generate through contact with sunlight, can lead to rickets. But the list of serious ailments linked to insufficient vitamin D keeps growing. Recent research has even reinforced the link between vitamin D deficiency and Multiple Sclerosis (see the MS Society for more information).

Given that the winter sun in the UK is not strong enough to enable our bodies to create the vitamin D we need, it's vital we get the vitamin from other sources. There's some in oily fish and eggs, as well as fortified breakfast cereals and margarine. But given the overwhelming evidence around vitamin D, surely it should be added to more staple foods in order to ensure the population gets what it needs? It would even make sense to add it to mince pies, yule logs, christmas pudding, advent calendar treats and anything else we tend to guzzle during the dark midwinter. Fortified brussel sprouts anyone?