16/10/2012 13:27 BST | Updated 16/12/2012 05:12 GMT

Five Tips to Bullet-Proof Your Immune System This Winter

With memories of the Olympic summer fading fast, and the spectre of the cold and flu season looming, can anything be done to avoid the long winter months being punctuated by predictably periodic bouts of sneezes, sniffles and days off work cradling a Lemsip? Rather than lurching from one virus to the next, is it possible to bullet-proof your health this winter?

Of course, there's no end of so-called 'advice' out there on the best way to boost your immune system, but the reality is it's a pretty mixed bag of offerings, ranging from sound and sensible advice, to pure ill-conceived cobblers, and pretty much everything in between. So it's high time to cut through this mire of misinformation and give my five tips to bullet-proof your immune system this winter - and guess what, there's not an Echinacea tincture or Vitamin C pill in sight.

1.Big-up seasonal fruit & veg

I know, totally obvious, so let's get this one out of the way first. Max-up the amazing seasonal produce that winter has to offer to keep your fruit and veg intake high - think warming winter stews and casseroles and thick, hearty vegetable-based soups. Packing in your fruit and veg means that you'll ingest a veritable smorgasbord of nutrients to keep your immune system finely tuned, such as vitamin C, carotenoids such as beta carotene and lycopene, flavonoids, and a host of other phytoprotectants. Rather than grabbing for the nearest pot of antioxidant vitamin pills (like vitamins C and E), reach instead for Mother Nature's finest, with the likes of kale, purple sprouting broccoli, cabbage, carrots, red onions, mushrooms, garlic, citrus fruits, and frozen berries being notable winter winners.

2. Seek out selenium

There's a lot of fuss about what vitamins and minerals we should take, and mostly, it's wide of the mark. Selenium is different. Unlike most of the other widely touted nutrients, we experience a genuine lack of selenium in the British diet . Selenium is essential to health, being integral to our antioxidant defence system, with a dietary deficit paving the way to a compromised immune system, and ultimately even increasing susceptibility to serious illnesses such as cancer. As we detail in The Health Delusion, for women in the UK, a selenium supplement of 50-60mcg daily will raise levels to the ideal range. For men in the UK, a supplement of up to 100mcg daily is recommended.

3. Don't be D-ficient

As summer fades, so do our vitamin D levels. From now (October) till the end of March, even on a sunny day, it's impossible to make vitamin D in Britain, plunging as many as 90% of us into deficiency. Vitamin D bolsters our resistance to disease and is crucial for a strong immune system. Whilst the jury is out on exactly how effective vitamin D is in staving off colds and flu (you can read more on that here), the smart money is on keeping your vitamin D intake at an optimal level. As we've discussed in detail in The Health Delusion, adults in the UK can achieve and maintain an ideal vitamin D level (20-32ng/ml) this winter by supplementing 1,100-1,200 IU of vitamin D daily from October through to March.

4. No guts, no glory

There's an old adage taken from Hippocrates that says 'all disease begins in the gut' and with two thirds of our total immune response controlled by the gut it's easy to see why. As well as being important for the smooth running of our digestive system, research is now showing how our friendly bacteria play an important role in keeping our immune system in good working order too. That makes nourishing our friendly bacteria, by supplementing with either a reputable brand of probiotics (friendly bacteria) or prebiotics (a type of fibre that feeds our friendly bacteria) a natural way to bolster a stronger and more balanced immune system this winter.

5. Stay active

Whilst extricating yourself from a warm cosey duvet and embarking on exercise on dark, cold, winter days may seem a bleak prospect, it could put a sizeable dent in the risk of succumbing to the common cold. For example, a study of around 1,000 adults found that those who frequently engaged in regular exercise almost halved the number of days spent with upper respiratory tract infections, compared with their sedentary counterparts [1]. Not only that, even when they did fall ill, they suffered less severe symptoms. But beware too much of a good thing, as extreme and excessive exercise can have the opposite effect on immunity.

Note: The information in this article should not be treated as a substitute for professional medical advice; always consult a medical practitioner

[1] Nieman DC et al (2011) Upper respiratory tract infection is reduced in physically fit and active adults. Br J Sports Med 45(12):987-92