Boosting immunity to stop getting sick

It’s an unfortunate inevitability that at some time or another, illness will descend upon any work place.

Gastroenteritis can be difficult to avoid and in environments where there is close contact, it can spread like wild fire. Washing hands is vital to avoid infection, alcohol gel can also be used, but is not as effective as thorough hand washing. Here’s what the NHS says on medical treatment.

From a food point of view, it is especially vital for athletes to try to maintain nutritional intake to prevent muscle wastage and maintain energy levels. Easier said than done when you can’t keep anything down! If possible, and even if there is no appetite, small amounts of plain food and higher calorie fluids eg. toast, fruit juice, breakfast cereal, plain biscuits, or any food that you feel you can tolerate should be eaten.

It is possible that following recovery from gastroenteritis, the gut may have become intolerant to lactose (milk sugar), causing continued diarrhoea, and possibly abdominal pain and bloating. This is because the enzyme, lactase, which breaks down the lactose has been affected. Normal milk can be replaced with Lactofree Milk, tolerance to other dairy products varies. A dietitian can advise further on lactose avoidance.

In a previous post, I discussed the numerous reasons for lowered immunity during training for athletes:

  • repeated cycles of heavy exertion
  • exposure to germs and bugs
  • mental stress
  • lack of sleep
  • poor nutrition
  • weight loss

The first two points, repeated cycles of heavy exertion, and exposure to bugs certainly apply to the London Irish squad in pre season training, hopefully less so the mental stress, lack of sleep, poor nutrition and weight loss.

So what can be done to reduce the possibility of becoming ill?

Nutritional immunology is a rapidly growing area, and four key principles have emerged:

1. Almost all nutrients in the diet play a crucial role in immunity. A varied, healthy diet provides all these nutrients in most healthy adults, and mega doses of vitamin/mineral supplements do not “boost” immunity above normal levels.

2. Poor energy and nutrient intake can reduce the immunity and susceptibility to germs and bugs. Poor protein intake reduces immune function and strongly increases risk of various types of infections.

3. Some nutrients (glutamine, arginine, fatty acids, vitamin E) provide additional benefits to immunocompromised persons (e.g. the frail elderly) or patients who suffer from various infections. Currently there is a lack of evidence to support the use of these in preventing exercise-induced immune suppression and protection from infection.

4. Some supplements may prove useful in countering immune suppression for healthy adults during unusual mental and physical stress e.g. omega-3 fatty acids from fish oils reduce inflammatory responses.


Of the various nutritional countermeasures that have been evaluated so far, carbohydrates before, during, and after prolonged or intense exertion has emerged as the most effective way to ensure less of a negative effect on the immune system. Athletes intent on reducing body fat by avoiding carbohydrates should be aware that this may impact on their immunity.

shutterstock_85815004Strategies to ensure good carbohydrate stores to optimise immunity:

  • Have a carbohydrate-based snack before you start high intensity training, particularly hard morning training.  If you are unable to tolerate something before you start exercise, have a source of carbohydrate during the session such as a sports drink (6-8% carbohydrate)
  • Have a carbohydrate-based snack shortly after training to start the recovery process.  This is of particular importance for athletes training more than once a day with limited time to recover for the next session.
  • Base meals around nutrient-rich carbohydrate-containing foods and fluids.  Rice, pasta, bread, cereals, fruit, starchy vegetables and low-fat milk and yoghurt are nutrient-packed carbohydrate-containing
    Balanced meals with carbs, protein & veg

    Balanced meals with carbs, protein & veg

    choices. The aim is to match daily carbohydrate needs with an appropriate amount of carbohydrate-containing foods and fluids throughout the day.



Probiotics may benefit athletic performance indirectly by maintaining gut function and health, preventing the immunosuppressive effects of intense exercise, and reducing susceptibility to illness. Substantial evidence exists indicating that probiotics can reduce susceptibility to acute infectious diarrhoea (athletes may be particularly susceptible during foreign travel). Probiotics come in tablet or liquid form eg. Yakult. Tablets tend to be more potent, and are available from health food shops.

A balanced and nutrient rich diet is fundamental to avoiding illness for those undergoing intense physical exercise. Current opinion is that athletes should invest in nutrient-rich foods and fluids that provide sufficient energy and a wide range of vitamins, minerals and other important chemicals, such as phytochemicals, found naturally in foods. When this is not possible the use of supplements such as multi vitamins and omega-3 fish oils.


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