Swim Magazine

How To Protect And Boost Your Immune System When Cold-Water Swimming

The chilly, crisp winter days are upon us and those of you who are partial to cold-water swimming will be enjoying the falling water temperatures. At the same time, the approach of Christmas means lots of celebrations and you may be wondering about the best way to keep yourself healthy while enjoying parties and festivities. Dietitian Isabel Anderson has top tips on how you can optimise your eating to help fight off colds and flu and thrive at this challenging time of the year.


WORDS: Isabel Anderson

PHOTO: Shutterstock

What diet is best to boost your immune system when regularly cold-water swimming?

When your body needs to fight an illness, it requires energy. Following a long or intensive swim session you are at greater risk of illness as you will have used up some of your energy reserves. Your immune system may not now have access to the energy it requires to mount an effective immune response, and so won’t work as efficiently. It’s therefore important to ensure you’re refuelling with carbohydrates after these sessions to help protect yourself against illness.

Protein is also an important part of a swimmer’s diet as it’s needed to repair and build muscle after exercise. It’s also a crucial part of your immune system, providing the building blocks for making immune cells and antibodies which fight infections. To get the most out of the protein in your diet, include it in every meal and snack.

Your body can only process a certain amount of protein at any one time. The rest is converted to sugar for energy, then stored as fat if not used. Consuming protein in smaller amounts frequently is more beneficial than large quantities at one or two meals. Remember also the quantity you need across a day – the optimal meal portion is individual to you as it depends on your age, weight and activity levels.

Polyunsaturated and monounsaturated fats also play an important role in the immune system, with a special mention for omega 3, found in oily fish. Omega 3 is also in nuts and seeds, but the body can struggle to convert this into the active forms known as EPA and DHA. Monounsaturated fats are found in nuts and seeds as well as avocados, but an excellent source is olive oil, especially when used to dress salads or as an accompaniment to bread, rather than heated during cooking.

How to control your blood sugar levels as a cold-water swimmer

Fluctuating blood sugar levels and especially abnormally high blood sugar levels can disrupt the normal workings of your immune system. Choosing foods that are digested slowly will help your body to regulate these levels. Wholefoods containing fibre and with no or limited processing tend to be digested slower and therefore can help to stabilise your blood sugars. Adding protein will slow digestion of food and make you feel fuller for longer, meaning you’re less likely to reach for the high-sugar snacks later on, so protein is a win-win for swimmers.

If you’re swimming soon after eating, you’re likely to need lower fibre food options. Also, if you’re swimming for more than 75 minutes, high-sugar drinks and snacks are likely to be your go-to for fuelling. Don’t worry about a negative impact on your immune system, as swimming will help your body take the sugar from your blood at a faster rate to help fuel the exercise. This means your blood sugars won’t rise as much as they otherwise would with the same level of sugar. Exercise is very beneficial for controlling blood sugar levels over the longer term as well, so definitely something to be encouraged.

It’s also worth noting that stress levels and lack of sleep can negatively impact your blood sugar levels; stress especially can cause them to rise independently of what you’re eating. Both of these can also result in you reaching for high-sugar quick-fix foods to help you feel better, when actually what you need is a nutritious meal or snack to help balance your blood sugar levels and not cause a crash later on. Swimming is great for helping to manage stress, again assisting you to keep your blood sugar levels under control.

Overall, eating a wholefood diet with plenty of plants and protein sources will help keep you healthier, so you can keep swimming throughout the cold months.

Disclaimer: if you have an underlying health condition such as chronic kidney disease or diabetes then you should check any dietary changes with a dietitian. Your GP will be able to refer you.

You can read more articles about healthy diet and lifestyles in issue 7 of Swim magazine.