Blog post written by Conrad Goodhew - performance dietitian (NZRD)
When it comes to immunity, we need to tackle it from all angles. The messages are the same as always; however, I think we all now have an incentive to listen and think about the positive habits that we can create during this time. This is a simple guide to get your understanding of immunity up to scratch.
The reason for a picture of a castle, it will represent our immunity. It is our defence mechanism – we are able to build and repair it, but it takes lots of little bricks to create a large wall.
What is immunity?
Immunity (noun): the body’s ability to avoid or not be affected by infection and disease.
Many think immunity is ‘activated’ when we get sick, but in reality, it is a sign of good or poor health. Our immune system protects us from chronic illness, such as cardiovascular disease (CVD) and cancer, but also acute illness, such as a bacterial or viral infection. A healthy diet is one key modifiable factor to improve immune function, reduce inflammation, and boost overall health.
Your immunity, put simply, works in 3 stages: protection, fighting and memory. Our organs (yes, skin is one too) each have specific roles in working in tandem to ensure your body is functioning the best it possibly can. The body manages chronic illness (e.g. CVD), viruses, and bacteria differently – this is why experts are asking for specifics around what type of illness you have (i.e. it warrants a more in-depth discussion).
What foods do we target?
There are no specific targets in building immunity, it is just important that you are getting a variety of foods and colours to ensure you are getting enough of the right nutrients. Think of each of your bricks a different micronutrient, i.e. one is Vit D, one is Zinc, etc. Your body needs a range of vitamins and minerals to function effectively; however, Vitamins A, D, C, E, B6 and B12, Folate, Zinc, Copper and Selenium have been found to be crucial for the functioning of your immune response – I’m not suggesting that you go and stock up on each of these supplements, but to recognise that there is no one ‘fix-all’ vitamin/mineral.
Whole foods provide maximum nutrients: So, think lots of fruit and vegetables (5+ serves per day, more is better), whole grains and good quality fats. This is the reason why we don’t encourage removing any given food group.
Benefits of food
Fruit and Vegetables: They provide a range of vitamins and minerals, they also contain things such as phytochemicals which are powerful antioxidants that fight damage caused by free radicals. They are also packed with fibre.
Whole grains and Legumes: Full of B-Vitamins and fibre. Fibre is vital for the use of our gut microbe (good bacteria) to assist in our overall health. Here is a tip: try to hit a fibre target of >35g per day from food, as this will mean that you are consuming more whole food, which also has additional B-Vitamins.
Fish and Seafood: Omega 3s and Vitamin D. Both of these are unable to be produced by the body so therefore you will be relying on your diet to ensure you get enough of each. Found in some other food sources, such as in nuts and seeds, but are most abundant in this food group.
Dairy, Eggs and Meat: A great source of protein, minerals, and fat-soluble vitamins (plus overall calories). They also provide cholesterol which plays a vital role in the production of steroid hormones in the body.
Nuts and Seeds: Fibre, plant-based omega-3s, unsaturated fats, plus a range of minerals. This group are great to add to many breakfast meals or salads to improve nutrient density.
Green Tea: Has been found to have anti-inflammatory properties which can assist with immunity, due to its major component of epigallocatechin-3-gallate (EGCG).
Herbs and Spices: Epidemiology studies have shown that herbs and spices can play a pivotal role in overall health and inflammation management. They are ‘calorie-free flavour’ so it’s basically a no-brainer when it comes to adding these to your everyday meals.
Starving a cold
Overall energy is vital for immune function there is no such thing as 'starving a virus’. Studies have shown that a reduction in calories can benefit longevity of life; however, there is also evidence that a significant reduction in calories can impair immune function. In lay terms, it is ok to continue to reduce your calories by 10-15% without significant complications; however, significant dietary intervention (i.e. your typical ‘diet’ today) can have consequences. It is also important to note that your body’s energy requirements will also increase when you are unwell.
The importance of hydration is well-known; however, I still want to touch on this. The best way to test your hydration status is from your urine in the morning. If it is golden, you need to ensure you are drinking enough during the day. If you find that you are drinking lots of water (worth tracking this), and are still waking up very yellow, I suggest you look into the use of hydration tabs as there is a chance you may have an electrolyte deficiency – mainly for those in physical jobs or who exercise often (since electrolyte deficiency is associated with sweat loss).
During a fever or illness, hydration is vital to ensure the body’s systems are working effectively. Our kidneys and liver are our best defence to ‘detox’ the body, and euhydration is important to ensure that blood can pass through these systems effectively to clear out the nasties. This is vital when you are sweating a lot!
Sunlight is essential for Vitamin D production, as it is difficult to meet recommendations through diet alone. When you can, aim for 15 minutes exposure of the chest, face and arms in the morning or afternoon. Use sun protection for prolonged exposure. Sunblock may inhibit the production of Vitamin D; however, systematic reviews indicate that the chance of this causing any deficiency is low.
Eating for Mental Health
This is a different type of illness, but still an illness nevertheless, so I will touch on it. There is a large amount of literature available that shows the strong link between a good quality diet, high in fibre and nutrients, and reduced signs of anxiety and depression. Here is a quote published by the Nutrition Society at Cambridge that sums it up the best.
"Due to the scale of the burden of mental, neurological and substance-use disorders and the universality of food as a modifiable risk factor, even small improvements in the nutritional environment may translate to large gains in mental health and wellbeing at a population level."
In lay terms, if you emphasise improving your diet, there is a very strong possibility that it might improve your mental health too.
THIS IS THE GLUE THAT HOLDS YOUR CASTLE TOGETHER
I cannot emphasise the importance of ensuring that you have good sleep hygiene. Targets for sleep are 7-9 hours per night. It is vital to understand the impact sleep deprivation has on suppressing our immune system. Sleep is non-negotiable and there is no pill that can reverse the effects of poor sleep hygiene. Most importantly, sleep is not money, you cannot accumulate it over time or pay off the debt later.
How do I get quality sleep then?
Create regularity: Your circadian rhythm is very important tool for you to understand. Hormones are released at different times during the day that are based on your previous blueprint. Set regular exercise, bed and wake times to ensure there is some consistency in your life.
Avoid weekly jetlag: Think of your 6 am wake-ups during the week, then 2 days per week (weekend) you sleep in until 11 am. You are essentially getting jetlagged 2 x per week. Think about how you would feel if you were to cross a 4h time zone twice each week. To those of you who do shift work, I apologise.
Sleeping pills and alcohol: these may help you get to sleep, but it is not quality sleep. It is important that we move through the stages of sleep (i.e. N1,2,3, REM) to ensure quality.
For years, it has been thought that exercise temporarily suppresses your immune system, due to the changes that occur in the para- and sympathetic nervous systems. However, evidence suggests this is not the case. Exercise can become an issue during times of over-training (mostly high volumes of high-intensity). This is commonly seen in athletes and those weekend warriors without a structured training plan. Disordered eating can also be seen within these groups and is a compounding factor. Put simply, exercise won’t suppress your immune system acutely; however, chronic overtraining and poor training prescription (alongside poor nutrition) will have a negative impact over time.
How about ‘sweating out your illness’? Well here are a few things you need to consider: Are you contagious and do you really have to go to a public gym (there are so many online workouts available)? Don’t be the dick that brings an illness into the gym as you think ‘you’re ok’.
Where is the illness located? Use this simple guide to determine what to do:
‘Above the neck’: Things like a runny nose, congested sinuses, sneezing or a minor sore throat. This is considered a common cold and you are usually ok to train. Still consider the intensity of your workout as you may be better to go for a walk or light jog as opposed to doing a HIIT workout, for example.
‘Below the neck’: Such as chest congestion, cough or gastro issues. This can include a fever, fatigue or muscle aches. This is when your body is in full recovery mode, and it requires more energy than your exercise does. Also, deep breathing can further increase the severity of your cough (due to the bug moving further into your lungs).
Don’t forget simple gym etiquette too! Wash your hands, cough/sneeze into your elbow, use a towel and wash the equipment down!
Treat exercise as the moat to your castle – it is vital to improving your defensive systems, but it also can be hugely detrimental if it overflows.
Supplementing nutrients every day is like trying to add a brick that is already there, what happens is your body just gets rid of it (or it can become toxic). Supplements should be used when there is a potential for bricks to be missing (i.e. you have an underlying reason why you are unable to meet your requirements), but are not necessary when the overall quality and variety of what is consumed is good.
Some high dose supplements will be like throwing a flaming ball off of your castle, but others will be like throwing a bucket of water – it may look like you have slowed it down, but in reality, it has had no impact.
Supplements that can assist during infection (adults), best to have available during early stages (i.e. scratchy throat) – practical recommendations:
Vitamin C: 5-8g per day for 7 days only, as there is potential for Vit C overdose for long periods of time. This is well above RDI.
Vitamin D: 4000iu per day for 7 days: Even with sunlight exposure this will be under the threshold for toxicity. Only beneficial for specific illnesses; however, there is no harm in supplementing this without any specific diagnosis for a short amount of time to boost your immunity.
Zinc: 75-100mg/day from early-onset throughout the duration of a cold.
Lastly, Probiotics: 1 x daily probiotic containing ~1010 Lactobacillus and/or Bifidobacterium species. There is some evidence that taking probiotics may aid in the prevention of URTI’s; however, more research is required.
If you made it this far, fantastic! Remember that our immune system is like a castle, and there are multiple factors that create our defence. So, next time someone tries to sell you a ‘this will fix your immunity’ product, remember a single brick won’t stop an army.
This is an example of some of the information I would discuss during consultations and seminars – it’s not all just about what you are eating. If you are interested in finding out more please check out my services online
It is important to note that the information supplied within this blog does not detail all of the available evidence and is not an individualised plan. It is written for the 'average person' so that they can digest the science.