Column 7, May 2008

Immunity and Running

There are a vast number of benefits to be gained from recreational running, including improvements in our cardiovascular health, mood, self-esteem, immunity, weight control and protection against muscle and bone loss with age.

Can distance running or intense running sessions reduce our immunity though?

There is some evidence to show that immune function is suppressed in high performance runners, and that the incidence of colds and flus increases during periods of endurance training. A single bout of acute intense exercise may also suppress immunity for several hours afterwards.

As a competitive runner, it can be immensily frustrating to be landed with a cold in the days before a race! So here’s a few nutritional strategies to reduce your chances.

Nutritional strategies to maintain good immune function in distance runners

Consume 30-60 of carbohydrate/hr during runs/races longer than 90mins. Blood glucose levels drop after about 90mins running, triggering the release of cortisol and other stress hormones, which in turn suppress the immune system. Consuming carbohydrate helps to maintain blood glucose levels, improve performance, and maintain immune function.

Eat a balanced diet that is high in unrefined carbohydrates and contains adequate protein and polyunsaturated fats. Distance runners are generally aware of consuming enough carbohydrate, but in pursuit of leanness, they sometimes underemphasise the importance of dietary fat. Deficiencies in protein (required in higher amounts by endurance runners), or fat, will impair immunity.

Lose weight sensibly (if required) under the guidance of a Sports Nutritionist, and at a gradual rate of around 0.25kg/week. Over-restriction of calories will impair immune response. Nutrient supplementation may be recommended during this period of time.

Avoid becoming underweight. It’s a fine line between being a lean, mean, endurance running machine and being a weak, sickness prone waif. If your Body Mass Index has dropped below 19 (calculated by dividing weight in kg by height in metres squared, eg a 1.65m tall runner weighing 54kg has a BMI of 54kg ÷ (1.65 x 1.65) = 19.8) then I would suggest consulting a sports doctor or sports nutritionist in conjunction with your coach. Individuals vary in their optimal weight for performance and health.

Test for and treat nutrient deficiencies. B12, Iron and Zinc deficiencies are common in runners, and will impact immunity. If deficiency is an issue, then regular (3 monthly) blood monitoring is advisable.

Consume foods rich in vitamins A, C and E, beta-carotene, B6, B12 and the minerals zinc, iron and selenium (see ‘immunity super foods’). These nutrients are involved in immune response or contain powerful antioxidant nutrients and phytonutrients that neutralise cell-damaging free-radicals produced during long-distance running.

Avoid over-supplementation. Mega dosing on vitamin E, iron and zinc for example can actually reduce immunity.

Immunity ‘Super foods’

Berries – of any kind are some of the highest antioxidant phytonutrient foods

Apricots, Carrots, Pumpkin, Spinach – rich in beta-carotene, which our body converts to vitamin A

Walnuts – rich in phytonutrients, vitamin E

Flaxseed/Linseed – Rich in linolenic acid, a polyunsaturated fatty acid essential to immune function

Wholegrains and Cereals, Brown Rice, Kumara, Chickpeas – high in Vitamin B6

Fish and Seafood – Rich in B6 and selenium (NZ’s soil is low in selenium, so our seafood tends to have a higher content than our meats)

Citrus fruit/Kiwifruit/Red Peppers – loaded with vitamin C

Lean Venison, Beef and Lamb – iron, zinc, B12

‘Live’ Yoghurt and Yoghurt ’Shots’ – a natural source of probiotics

Mussels – packed with iron, zinc and selenium

Supplements

A range of supplements are promoted to boost immunity, but scientific evidence to show they prevent exercise-induced immune impairment is inconclusive.

Also be aware that many nutritional products cannot guarantee they are free from banned sporting substances (with the exception of USANA). My view is if it does no harm, you can afford it, and you believe it works for you, it will probably have a positive effect!

Supplements promoted as ‘immune-boosting’

Vitamin C – some studies have shown that consuming 600mg-1g/d can help reduce colds in marathon runners. This level can only be achieved through supplementation (the exception to the mega dosing rule).

Vitamin E – although beneficial from dietary sources, mega dosing may suppress immunity

Zinc – may reduce duration of colds if taken within 24hrs of initial symptoms.

Probiotics or ‘friendly gut bacteria’ - some studies indicate a reduction in the length and severity of colds/flus in distance runners.

Garlic – may protect against colds.

Echinacea – some studies show a protective effect in preventing colds when taken short term before competition. May reduce severity and duration of colds.

Glutamine – a branched chain amino acid important in certain immune cell production. Supplementation during and after exercise shows conflicting results.

Other unproven supplements include olive leaf, bee propolis, ginger, and green tea.

Immunity Boosting Winter Smoothie Recipe

Blend together...

½ c (1 sml tub)             ‘Live’Yoghurt (eg Yoplait Elivae, Anchor Symbio)

¾ c                                  Frozern Berries

½ c                                 Grape or Cranberry Juice (also very high in antioxidants)

Small handful           Walnuts and Linseed

dollop                             Manuka Honey (optional)

Non-nutritional advice to prevent the winter bugs taking hold!

Get enough sleep - When travelling to races, plan stop-overs on long-haul trips. Discuss pharmaceutical options with your doctor (eg melatonin) to quickly alter your body’s clock onto the local time zone. Use ear plugs, eye masks, or travel with your own pillow if it improves sleep.

Manage stress and stay positive – running in itself can be a stress reliever, but there are many other techniques which will reduce circulating stress hormones, and therefore vulnerability to sickness.

Avoid over-training - You own perception is good indicator of whether you are recovering from runs, or chronically fatigued. More definitive indicators include reduced running performances, increased EMHR (early morning heart rate), and reduced max HR during ‘lactate’/’anaerobic threshold’ workouts. If the heart rate changes by 5-10 beats you need to discuss recovery strategies with your coach.

Rest or train easy when sick – learn when to back off. Training hard through sickness can result in post-viral chronic fatigue, and recurring sickness.

Dress warm after runs

…and remember… when it’s cold, wet and windy out there running, the coffee, hot food and snugly warm clothes feel insanely more enjoyable!

Have fun!

Marnie Oberer