Boosting the Immune System
With the mornings becoming cooler and days getting shorter, it’s a good time to look at some of the myths that exist around nutrition and the immune system. Knowing what really works will help keep you healthy and consistently on the training track over the winter months.
MYTH: Vitamin C prevents colds
THE FACTS: Despite its popularity in the general population, there is little evidence to support the use of high doses of Vitamin C for preventing the onset of the common cold. But, there is some research to suggest that Vitamin C may have favourable effects on reducing the duration of cold symptoms. At the moment, however, there is insufficient evidence to make recommendations on the optimal dose and duration of supplementation to promote a speedy recovery from a cold.
YOUR BEST OPTION: Boost your intake of foods high in vitamin C at the first signs of a cold. Fruits and veggies including oranges, capsicum, dark leafy greens (e.g. kale, spinach), broccoli, berries, kiwi fruit, mandarins, tomatoes and chilli are all high in vitamin C and a great addition to a cold busting diet.
MYTH: Dairy makes you congested so you should avoid it when you already have a stuffy nose
THE FACTS: Numerous studies have found that milk is not associated with increased mucous production. Some people may experience a thin coating in the mouth after drinking milk. The good news is that this is not mucous and is usually only a temporary sensation so no need to cut out dairy when you’re in the midst of a cold. In fact, yoghurt and specialised drinks such as Yakult are an excellent source of probiotics. Probiotics are live microorganisms that have been shown to have beneficial effects on preventing the start of a cold as well as reducing the duration and severity of cold symptoms.
YOUR BEST OPTION: Including yoghurt in your diet each day provides you with a good dose of probiotics to help boost your immune function. Top your morning muesli with some, mix with fruit as a snack or tuck into a tub as a recovery snack after training. Alternatively start including probiotic drinks such as Yakult as part of your daily nutrition plan.
MYTH: A daily multivitamin or dose of ‘supergreens’ powders will keep your immune system firing
THE FACTS: Although there is some support for multivitamin and supergreen supplements the main benefit seems to occur in people with poor quality diets that don’t consistently achieve adequate intakes of fruit and vegetables. Often touted as a good “insurance policy” unfortunately multivitamins and supergreens are only a band-aid solution. There is also a growing body of research to indicate that chronic supplementation of antioxidants from pill/tablet/powder form can actually be detrimental for performance in athletes.
YOUR BEST OPTION: For the best immune boosting results you need to fix the underlying issue – your mum was right after all; veggies really are good for you! A diet rich in fruits and vegetables that provides a variety of nutrients will offer greater benefit to your immune system (and be less likely to undo your hard training) than supplementing one or a few nutrient/s in isolation.
MYTH: Vitamin D is only important for bones
THE FACTS: Vitamin D is most well known for promoting bone health but now its important role in immune function in the body is becoming better understood. Vitamin D is particularly important for T-cell mediated immunity – a fancy term for the bug fighters in our body. As we head in to the winter months, it’s a timely reminder that even if you train and compete outdoors, you can be at risk of Vitamin D deficiency (especially those living in the southern states of Australia where the latitude limits UVB exposure and therefore Vitamin D synthesis). If you train indoors or you catch only a glimpse of sunshine at the start and end of the day, it might be worth checking in with your GP to check your Vitamin D levels and see if you need a top up over winter.
YOUR BEST OPTION: Get out for a walk in your lunch break! Recommended sunlight exposure during winter for people living in the north of Australia (e.g. Cairns) is ~9-12 minutes/day, in Brisbane or Perth is ~15-19 minutes/day and in the southern states is between 26-47 minutes/day. Dietary sources of Vitamin D are limited but small amounts can be found in oily fish, egg yolks, mushrooms and fortified milks and margarine. Given the difficulty in obtaining Vitamin D from the diet and limited sunlight exposure in the winter months, supplementation with Vitamin D3 is likely required for athletes who are Vitamin D deficient (but check in with your GP first).
MYTH: You should cut down your carbohydrate intake over the winter months to avoid growing a ‘winter coat’
THE FACTS: Although you may need to tweak your carbohydrate if you’re hibernating from training over winter, there is good evidence to support the role of carbohydrates in counteracting the immune suppressive effects of exercise. Exercise leads to increased levels of a number of stress hormones and carbohydrate has been shown to be beneficial in dampening this response. So, if you’re training through the winter months, it’s important that you are mindful of your carbohydrate intake around exercise, especially during any heavy training phases.
YOUR BEST OPTION: If you’re taking a break from training over winter, make sure that you adjust your carbohydrate intake to match your training load to avoid an unwanted increase in weight while energy needs are reduced. But, if you’re planning on braving the cold, remember to fuel your body before, during and after training with quality carbohydrates to not only keep you training well but to fight off any colds too.
So there you have it, a quick snapshot of the latest information on the role of nutrition in immune health. If you’d like more information to help you perform and stay healthy this winter, check in with an Accredited Sports Dietitian.
