1st November 2010 Words: Lynn Clay Photos: Mike Prior & Tom Simpson
Eat and drink right this winter; you’ll curtail those colds and keep riding.
If it seems like everyone around you is sneezing and sniffling instead of hibernating, to avoid catching their colds why not take some steps to bolster your immune system during the cold season and beat those bugs?
The off-season typically sees cyclists easing off on the mileage and giving the body a bit of a rest. This tends to be a good thing, enabling a stronger immune system to fight off any bugs that are lurking around at this time of year.
Organising your diet to include lots of immune-boosting foods can give you some added protection and often means replacing some nutrient-poor calorific foods with lower calorie nutrient-rich foods that will also help you avoid weight gain in this period.
The first step towards supporting the immune system is to make sure you replace the carbohydrate you are using while cycling, refuelling straight afterwards. This is not the time to go low carbohydrate, but neither do you have to pile your plate with copious amounts of pasta or rice at each meal.
Indeed, some of the most important nutritional strategies for immune boosting have focused on carbohydrate intake before, during and after exercise, a familiar practice for most regular cyclists. Consuming carbohydrate in this way seems to diminish some of the immunosuppressive effects of training, along with decreasing the release of stress hormone (cortisol).
This means you can keep the carbohydrate content of your general meals to a moderate level. A carbohydrate-rich snack one to two hours prior to exercise, such as porridge oats, a small bagel and jam, or a carbohydrate drink will easily match the carbohydrate need just before you ride.
Healthy snack bars
While you’re on the bike, it is often easier to opt for a carbohydrate drink and, on rides of over 30 miles, complement it with carbohydrate-rich snack bars such as Eat Natural Bars, Clif Bars and Bounce Balls. In the immediate period after training, a recovery meal is essential to ensure you don’t fall prey to infection in that slightly nutrient-depleted period.
Add some glutamine
One of the purported benefits of consuming adequate carbohydrate is that this also helps to support glutamine levels in the body, which researchers have linked with immune function. A research study in 1992 suggested that a decrease in plasma glutamine following endurance exercise created an increased susceptibility to catching a common cold or infection.
The researchers found that a 5g dose of glutamine after strenuous exercise, with a further equal dose two hours later, lead to a reduction in rates of infection in the study sample of 200 athletes. Indeed, 80 per cent of those in the group ingesting glutamine reported no infections or colds, compared to only 48 per cent in the control group drinking a placebo maltodextrin (carbohydrate) drink — a staggering 32 per cent difference. You can achieve this by using a recovery drink with glutamine in it, or by using a glutamine supplement and adding it into food.
But what else will keep us well? If we aim to replace carbohydrate and supplement our glutamine, but neglect the rest of our diet, then this is missing the point. It is important to recognise what other basic foods and practices will help to keep us fighting fit.
Include antioxidant-rich foods
As oxygen use during exercise has been shown to increase free radical production, it is important to include anti-oxidant-rich foods in the diet, which can counteract these free radicals and bolster the immune system. One of the antioxidants most commonly associated with preventing colds is vitamin C, which has a reputation as a great immune system booster. Regular exercisers can generally consume their daily allowance over three servings of fresh fruit and two cups of cooked vegetables daily, selecting high vitamin C options such as sweet peppers, citrus fruits, strawberries, kiwi and broccoli.
This will, however, depend on the quality of the fruit and vegetables, and therefore it is common practice for athletes to consume a vitamin C supplement to ensure their daily intake is adequate. A 250mg daily dose has been shown to saturate the body’s stores with vitamin C.
Fruit and vegetables
Essential regardless of your level of supplementation, sticking with a high intake of fruits and vegetables should pay off. They contain hundreds of phyto-chemicals, providing many preventative health benefits, and are also excellent sources of carotenoids, that boost the activity of white blood cells.
Beta-carotene can also be converted to vitamin A in your body, an important nutrient for the immune system. When selecting your fruit and vegetables, always opt for the darker coloured varieties, as these tend to be richer in antioxidants.
Other nutrients essential to a strong immune system include zinc, iron and selenium. It has been suggested that 60 per cent of inactive UK men are zinc deficient, and as zinc is used at an even greater rate during exercise, male athletes run an even higher risk of being deficient.
Zinc deficiency can lead to poor wound healing, reduced energy levels, suppressed immune function and low testosterone production. The daily requirement is 8mg for women and 11mg for men, which can be achieved through eating foods such as steak, chicken, crab, fortified cereals, green vegetables and nuts. Not only has zinc been shown to provide general immune system support, but if you are still unfortunate enough to catch a cold, it has also been shown to reduce the duration of symptoms by almost half the time.
Iron intake can also be achieved through red meats, such as steak, and fortified cereals, with bran flakes sitting at the top of the iron-rich cereal tree. Green vegetables offer a reasonable source of iron, but the best iron suppliers without doubt are mussels, providing the 14mg daily requirement in just 100 grams. Iron levels need to be maintained with a regular intake of iron-rich foods, otherwise deficiency and fatigue will result. Women need to be particularly regimented in their intake of these foods during their menstrual periods, when iron losses in blood increase.
Zinc and iron, although needed each day, should be taken at different times of the day, as they compete for absorption, so bear this in mind when planning your meals or supplements.
Evidence continues to mount to support the use of super-antioxidant selenium for immune system support. In spite of a recommended daily intake of 55 micrograms (mcg), however, it has been estimated that the average person only consumes up to 36mcg per day. A report in The Lancet in 2000 stated that selenium deficiency could cause impairment of the function of B-lymphocytes, which are important for immune function.
Further research has suggested that daily intakes of 297mcg per day improve markers of immune function, increasing the body’s resistance to viral infections. Foods naturally rich in selenium include white fish such as sole and swordfish, and meats such as kidney, turkey and chicken. Snacking on Brazil nuts, sunflower seeds and dried apricots can also help you to top up your daily supply, and a simple sandwich at lunchtime can also contribute, with wholemeal bread supplying a small amount.
The power of protein
Protein requirements in the diet should also be met, as low protein diets have been shown to compromise the immune system. General recommendations for protein intake for non-exercisers are 0.8 grams of protein per kilogram of body weight. Exercise, however, increases the demand for protein to between 1.4 and 1.8 grams per kilogram of body weight depending on training load.
This protein should be derived from a mixture of animal and plant sources, if your diet permits. Products such as dairy colostrum and whey protein can not only aid this protein intake but are also both easily digested in the body and have been linked with an increase in immune response after a period of supplementation.
Having the proper balance of fat in your diet, and choosing good fats, can also give your immune system a boost. While a very high-fat diet can compromise immune function, a very low-fat diet does not provide adequate amounts of essential fatty acids. Polyunsaturated oils that provide omega-6 and omega-3 fatty acids are good for the immune system.
While omega 6 oils are in plentiful supply in the average diet, omega 3 fatty acids are generally in greater demand. Walnuts, oily fish and flaxseed oil are good sources of this healthy fat, and in their absence, an essential fatty acid supplement should be used to provide between three and six grams daily.
Sun & Vitamin D
Essential fatty acid supplements will not only provide omega 3 but also top up your vitamin D intake. Vitamin D is also now recognised as playing a large role in the maintenance of a healthy immune system, with poor status linked to a reduction in lung function and the development of several cancers. Protecting the lung and respiratory tract from infection by stimulating the production of cells that fight infection, vitamin D has been studied for its potential role in providing protection from swine flu as long ago as 1949, so its resurgence in the last few years with swine flu travelling to the UK from Mexico, was no surprise.
Indeed, vitamin D deficiency has been shown to predispose individuals to respiratory infections, making them far more vulnerable to any flu, never mind the swine variety, and with cyclists generally suffering from more upper respiratory tract infections, it seems to make sense to ensure you are getting your daily complement.
The problem with vitamin D is that the main source is sunlight, and therefore, from October to March in Britain, our stores are generally being depleted.
Even if you’re getting outside regularly on the bike during these months, the lack of sunlight and angle of the sun mean that your body won’t be making any vitamin D.
In fact, even in the summer months, the body is unlikely to absorb sufficient vitamin D from the sun if you are outside before 10am or after 3pm, due to the sun’s angle, so dietary sources become necessary whenever there is difficulty obtaining sun exposure, to stop your stores from dwindling and to strengthen your immune system.
Dietary sources of vitamin D include egg yolk, oily fish, shitake mushrooms and fortified foods such as margarine. Therefore, for those of us who are not lucky enough to be jetting off to sunnier climes for a winter-sun training holiday, it’s wise to include these foods in your diet over the autumn and winter.
Fish is the richest food source, so it’s wise to eat it regularly to benefit not only from vitamin D but also from the omega 3 fats known to provide anti-inflammatory and heart health benefits. Sardines on toast, a salmon bagel or a mackerel salad all provide simple and effective vitamin D-rich post-ride lunches, and choosing a roasted salmon fillet and vegetables or tuna pasta with shitake mushrooms for an evening meal will provide plenty of vitamin D, too.
Including a vitamin D-rich food option in your diet each day during the autumn and winter seasons is likely to give you all the vitamin D you need for mood and immune support.
Supplements provide an alternative, with cod liver oil providing 400 to 1,000 international units (IUs) of vitamin D in one teaspoon, and vitamin D tablets can also be bought over the counter in many health food shops. Although vitamin D is linked with a variety of health benefits, if you’re supplementing, 1,000 IUs per day (25mcg) is recognised as the safe upper intake in the UK.
Sup it up
It seems that drinking the right stuff could keep you well, too. Ensuring you are drinking enough water is the first step to getting your fluid intake right, but with many of us overdoing the coffee and tea, we could also be stressing our adrenal glands from all that caffeine.
Caffeine in small doses doesn’t appear to be an issue, but swapping some of those hot drinks for green tea instead will reduce your caffeine intake while increasing your intake of immune booster theanine, which is abundant in green tea.
Experiment with different kinds, as some varieties of green tea are, let’s say, an ‘acquired taste’. Otherwise, opt for a honey and lemon or peppermint tea instead if you just can’t handle the green stuff.
With a well-balanced diet full of nutrient-rich foods, and avoidance of saturated fat-rich, processed or sugar-rich foods, you should find that not only is your natural immunity strengthened, but you will probably find it easier to maintain your weight during the off-season.
7 top immune-boosting foods
Green tea — full of the immune booster theanine
Sardines — rich in vitamin D and omega 3 fats
Brazil nuts — good for super-antioxidant selenium
Chicken — stuffed with cold-fighting zinc
Mussels — the best food for boosting iron intake
Sweet red peppers — full of carotenoids, which boost the activity of white blood cells
Broccoli – high in vitamin C
This article first appeared in the November 2010 issue of Cycling Active magazine.