Recruit Vitamin D to help win the war against winter bugs


Everyone in the UK should take vitamin D as a supplement – nutritional therapist Karen Geary explains what, how and why

Between October and April (when our shadow is longer than our height in the sunshine), we need to find vitamin D in food and supplements

In the UK, the National Institute for Health and Care Excellence (NICE) suggests that around 10 million people may be deficient in vitamin D. Why is it important, how do you get it and how do you know how much to take?

Why vitamin D?
We need vitamin D for our immune system to function. Immune cells have vitamin D receptors on them – when it is absorbed into the cells it provides a protective effect against infections and suppresses the replication of some viruses. These immune cells are mostly in the gut and it is thought that vitamin D may also support the integrity of the lining of the gut. There is also a suggestion that vitamin D may provide protection against other conditions (you can read more about that here). In other studies, vitamin D deficient individuals were found to be at higher risk of COVID-19 infection as compared with vitamin D sufficient patients.

How do I get vitamin D?
Our bodies cannot make vitamin D without sunlight and food (and then only in small amounts), so we need both sources or to use supplements. Vitamin D is fat-soluble, which means you need to eat fat to absorb it. Foods with vitamin D include oily fish, organic dairy, beef liver, mushrooms which have been exposed to sunlight, tofu, fortified milk products, fortified cereals and eggs. But we have to eat an enormous amount to get anyway near the recommended minimum amount – like 3kg of cheese, several cans of tuna and eight eggs! In the summer, when our skin is exposed to sunlight, 90 per cent of our total vitamin D comes from sunshine and we are likely to be making enough. However, between October and April (when our shadow is longer than our height in the sunshine), we need to find it elsewhere.
In food and supplements, there are two types of vitamin D: D2 which is found in plants, and D3, found in animal products. Our body makes D3, its preferred form, so it is important that you buy supplements in D3 form. Fortified foods are usually supplemented with D2.

Ed’s Note – I thought a vitamin deficiency sounded over-dramatic and ‘doesn’t-actually-happen-to-normal-people-like-us’.
Until, that is, my then-13 year old was diagnosed as vitamin D deficient after a couple of very worrying months. Dose yourselves, and dose your teenagers. The impact of low vitamin D levels is very real and deeply unpleasant.

How much to take?
An optimum level of vitamin D is between 75nmol/L and 100nmol/L. You can get an at-home test for £29 at and you can calculate how much you may need here.
Did you know that NHS and Public Health England recommends that anyone over 12 months old should take a supplement at a minimum of 400iu of vitamin D per day from October to March? This level, by the way, is barely enough to maintain current levels. Did you also know that the US – which is at a lower latitude than the UK (except Alaska) – recommends higher amounts, and with an upper tolerable limit?
It is always better to tailor the dose to suit you by testing your current levels.
However, if you are unable to take a test, a top-up dose over the winter of 2,000 to 3,000iu’s as a daily food supplement is sufficient and at this level is unlikely to lead to a too-high level unless your D3 is already too high, which is rare. Note this is much higher than the NHS recommendation. There are infant and junior supplements at a smaller dose also available. BetterYou offers good quality highly absorbable supplements. Unless you are taking blood thinners, I would always recommend taking vitamin D3 with vitamin K2. This is because the current research shows that vitamin K2 ensures that the calcium transported by the vitamin D is absorbed by your bones where it is needed.

We have to eat an enormous amount to get near the required vitamin D levels

Vitamin D from sunlight.
There is a wonderful free app for tracking this – though it is for the summer more than winter
Lack of sleep, stress, sugar, alcohol and poor diet can all deplete your immunity and no amount of supplementation can compensate for poor lifestyle. So always consider supplementation as part of a wider lifestyle approach to winter wellness.


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