Contrary to what may be being banded around on social media, there is no scientific evidence any one food or specific vitamin, nutrient or behaviour can actually boost and enhance your immune system. However what we do know is that there are a combination of lifestyle factors that can help us to maintain a healthy immune system.
It is well documented that taking part in some daily activity benefits the immune system. While some of us have had to change our usual routines, presently in the UK (at time of publication) we are still able to get outside and exercise alone as long as we maintain the regulations around social distancing. However there are also a number of ways of staying active indoors; many gyms are using technology to bring classes into the home space, online programs by PTs and coaches, and even just having a good old dance around the kitchen to some feel-good tunes. These are all great not just for your physical and mental health, but also maintaining your immune system.
However, what you do need to be mindful of is that this is also not the time to stress your body out by overcompensating and training harder or more frequently than you have done before. While it may provide some distraction from the current situation, there are a number of studies that have shown that overreaching the body in this way, can actually depress the immune system.
Good nutritional practices are necessary for performance and immune health. While healthy eating guidelines around consuming an increased volume of foods high in antioxidants are important, it also pays to focus your attention on all food groups. One of the key aspects of sports nutrition is tailoring requirements to training needs; so as load and intensity increases then nutritional intake will also need to marry this for an optimal outcome.
In addition to food intake, hydration plays a critical role in immune health. Hydration should not be ignored as it encourages the production of saliva which contains high levels of IgA; the body’s first line of defense. (Walsh NP, et al.2011).
While this is usually easy to manage during the warmer months, it can be a challenge in the winter when many of us find it more difficult to drink. Herbal tea, no added sugar squashes and flavoured waters can all encourage the consumption of fluid to maintain hydration around and during training sessions; post exercise milk based recovery drinks can encourage rehydration as well as glycogen restoration and muscle repair. (Gleeson, 2016).
One of the most important nutrients vital to consume, with regards to maintaining immune health in those that are physical active, is carbohydrate. Ensuring sufficient amounts throughout the day, particularly in high intensity or volume training blocks encourages appropriate fuelling and recovery for the body, preventing, the suppression of the immune system, which can be a result of inadequate fuelling. With many of us trying to maintain some form of training, all be it different to our norm, it is still important to consider your nutritional practices around training, whatever form of shape this takes.
As a recommendation, aim for a third of a plate at every meal of wholegrain nutrient dense carbohydrates such as sweet potato, pasta, rice etc. on training days and a quarter plate on non-training days. In addition, leading into higher intensity and longer endurance days, take on more carb based snacks and during endurance training session that are over 90 minutes, aim for 30-60g of carbs an hour.
In addition, these whole grains along with beans and pulses are prebiotics, nutrients necessary for the correct action of probiotics to encourage a positive environment for gut flora to thrive, benefitting immune health.
Another nutrient to be mindful of is Iron. Low iron levels can leave you more susceptible to contracting infections. Good dietary sources include red meat, eggs, fortified cereals, wholegrains, dried fruit, legumes, tofu and nuts. However remember that it is much harder to obtain iron from plant based sources; combining these with Vitamin C can help to enhance absorption.
The final point on iron is there is no need to supplement if you do not have low iron levels and taking a supplement is not going to “boost” your immune system. Studies have shown that only those who have low levels of haemoglobin or ferritin stores actually benefit from taking a supplement.
While you can obtain most of the nutrition you need through your diet, there are two supplements that are worth considering.
One of the main challenges, especially for UK based individuals due to the limited/lack of sunshine, is to ensure enough Vitamin D
Vitamin D is a very important nutrient when it comes to immune function and mood (He et al, 2013; He et al, 2016). Luckily it is very easy to supplement. The general recommendations in the UK are that we supplement from September through to April. From April through to September, the advice is to get outside for a minimum of 20 minutes a day without sun cream (this can then be applied after 20 minutes), between the hours of 11-3pm in order to absorb sufficient sunlight to make Vitamin D within the body. During these challenging times, even if you are able to just stand outside or sit in your garden for 20 minutes, it will definitely give you a boost. If this is not possible, then I would recommend maintaining supplementation during the current climate.
One thing to point out is that the darker you skin, the more difficult to make Vitamin D so you may need a bit more time outside but also still need supplementation in addition.
Numerous studies have demonstrated that a 12-week course of high strength probiotics can prevent the incidence and reduce the severity of upper respiratory tract infections in athletes in the lead up to and after a major competition (Gleeson & Thomas 2008, Cox et al 2010; Gleeson et al 2011; West et al 2011, 2014). While all our races for the first half of the year may be cancelled, many of us are still maintaining some form of training routine while we can and so this is probably worth considering.
While managing training and nutrition are critical for a healthy immune system, there are key lifestyle behaviours that can also have a big impact.
In order to maintain immune health it is important to obtain sufficient sleep each night, ideally around 8 hours. Few people know that Growth Hormone, responsible for physical repair is at its highest around 12-2am. Aiming to get to bed early enough will ensure that you make the most of this. To minimise sleep disruption aim to turn off laptops and phones at least 30 minutes before your preferred sleep time, as the blue light interferes with melatonin production - a key hormone required for quality sleep (Peake JM, et al. 2017).
In addition, as stated earlier, ensuring sufficient rest and recovery, both physical and nutritional are key to prevention of depressing immune function.
One we all need to be mindful of presently is managing stress. Stress not only impacts sleep but also the rise in cortisol can interfere with normal immune function. Many of us are going to be experiencing very difficult emotions in response to our present situation but it is really important to be able to reach out and ask for support. Try not to stay in your own thoughts too much – talk to friends and family. As much as possible try and stay in the moment. None of us know what will happen in the days and weeks to come but it is very easy to become catastrophic with your thoughts so where possible find ways to stay grounded, focused and anchored by daily activities that provide you with some calm and enjoyment.
Takeaways to support your immune health:
- Moderate physical activity can maintain a healthy immune system but overreaching/training actually depresses it.
- Carbohydrates, Vitamin D and Iron play a key role.
- Stay hydrated as this helps to produce saliva which is your first line of defense
- Pay attention to your sleep which aids physical and mental recovery
- Find strategies to manage stress
Sports and Eating Disorder Dietitian from Bradford-O-Avpn