When it comes to our immune system, it’s very easy to think of it as something that can be trained, strengthened or “boosted”. If you’re already at a healthy weight, staying active, eating a diet rich in protein, fruits, vegetables, wholegrains and healthy fats along with getting enough sleep, not smoking, not drinking excessively and managing stress, your immune system is going to be running just fine.

This is great news because as long as we keep these behaviours up we will be giving ourselves the best chance at fighting off foreign invaders.

Nutrition:

If you are following a nutrient rich, whole foods based diet then you’re already doing your body a world of good when it comes to optimising your immune system.

Adequate protein intake ensures we are creating the antibodies and enzymes that operate within the immune system.

Omega 3 fatty acids and other healthy fats in combination with fibre help regulate inflammatory markers.

A high amount of fruits and vegetables provide polyphenols which help promote immunity to foreign pathogens.

In addition to the above, the following have been shown to speed up recovery when we are struck down by a cold, flu or fever,

Vitamin C:

This important antioxidant has many roles in regulating the immune system that include:

• Protecting biomolecules such as amino acids, lipids and carbohydrates from oxidation due to environmental pollutants such as smoking and foreign pathogens.
• Production of nor-adrenaline and vasopressin that are central to the cardiovascular response to infection.
• Collagen formation leading to enhanced wound healing.

There are many more benefits but the take home message is that for optimal immune function, vitamin C is essential.

Aiming for 200mg per day from fruits and vegetables should be the daily minimum. However, when sick, supplementing with an additional 1000-2000mg can help with recovery.

Zinc:

The multiple ways in which zinc can impact the immune system include:

• Development and function of cells of the innate immune system.
• Macrophage (the cells that help clear inflammation) formation.
• Stabilization of membranes, reducing the oxidative stress that comes with being ill as your body fights off the infection.

Outside of poor immune function, zinc deficiency has also been linked to alopecia, diarrhoea, depression, low testosterone in males, delayed wound healing, poor appetite and mental lethargy.

Oysters and red meat are the best sources of zinc. Two or three oysters, 3-4 ounces of calf’s liver, or 8-12 ounces of red meat, can each meet the daily target on their own.

Good sources of zinc for vegetarians and vegans include whole grains, tofu, tempeh, legumes, nuts, seeds and fortified breakfast cereals but try to ferment or soak these products prior to consumption.

If going down the supplemental route, zinc sulfate, gluconate, acetate, and citrate are the best studied forms of zinc and work well. Aim for 7-15mg per day on an empty stomach.

Vitamin D:

Almost every cell that is part of the immune system appears to have a receptor for Vitamin D and a deficiency has been linked to depression, osteoporosis, respiratory infections, heart disease, breast and prostate cancers.

Estimates of the prevalence of vitamin D levels less than 50 nmol/L (or 20 ng/ml) have been reported as 24% (US), 37% (Canada), and 40% (Europe).

Also, middle east and South Asian countries, in spite of having abundant sunlight, have the highest rates of vitamin D deficiency. The prevalence of vitamin D deficiency in the general population in South Asia is reported to be in the range of 67-82% and in the middle east around 20-80%.

Unfortunately, it’s virtually impossible to meet our minimum vitamin D requirements through food alone which is why exposing ~40% of our skin to sunlight (10-30 minutes each day) or supplementation is recommended.

1000-2000IU per day will be enough to get most people in the sufficient range but mega dosing (10,000IU and above) is not advised as Vitamin D toxicity can lead to renal or heart failure due to extremely high levels of calcium in the blood (hypercalcemia).

Gut Health:

70% of our immune system actually resides in our gut and interacts with our very own microbiome.

Making sure that we feed our ‘gut bugs’ with good quality prebiotics from a diverse range of fruits, vegetables and wholegrains will not keep our digestion running smoothly, but can also help strengthen our immune system.

Sleep:

The need for sleep increases even further when we are sick so this can be a great time to really clean up your sleep hygiene.

• Install F.Lux on your laptop if you are prone to using electronics late into the night. Ideally no electronics would be the best but we need to be realistic too.
• Try not to eat too close to bedtime, especially if it is a heavy meal (at least 4 hours prior).
• Have a wind down routine you do every day as this will start to prepare the body and mind to sleep. Our bodies love routine.
• Keep a similar sleep/wake time, even on weekends.
• Use a form of continuous, non-distracting ambient noise (e.g. a fan or “white noise” machine / phone app).
• Maintain a cool temperature and adequate ventilation in the bedroom.
• Avoid napping during the day (if you must, limit the nap to less than 30–45 minutes).
• Reserve the bed for sleep and sex only. do not use the bed for work, watching television, or using other electronics.

Conclusion:

• Once you’re nailing the basics, there is no need to “boost” things any further.
• Eat a diet rich in protein, healthy fats, fruits and vegetables.
• Prioritise vitamin c, zinc and vitamin D when ill.
• Look after your gut.
• Get enough sleep.