4 Immune Boosting Nutrition Strategies

The following is not to be taken as medical advice, and I want to establish that in no way is this advice guaranteed to safeguard or cure you from COVID-19.

Rather, the information presented is associated to general immunity, which may or may not translate to the virus in question.
Regardless, I believe that in such an uncertain time, taking additional steps to potentially better your situation is a factor that each should consider through a comprehensive cost: benefit ratio. A few 1%’s can quickly add up, and im sure many would appreciate a few 1%’s at the present moment.

I also want to stress that due to the fact I am not aligned with a supplement distributor, I have no invested interest in pushing any particular products. 

1. Calories

One of the most important things you can do to keep your immune function high is to ensure that the body has sufficient macronutrients keep everything functioning exactly as it should be. When dieting, especially to lower body fat percentages, our immune systems can be compromised which can result in us becoming run down and susceptible to all infections, not just CORID-19 (Venkatraman and Pendergast, 2002). For those not dieting, getting sufficient calories in as an example of low hanging fruit which will assist your immune system in working precisely how it is supposed to. If you are dieting, whether it be for lifestyle purposes or for competitions, consult with your coach in order to formulate a plan of attack. 

2. Protein

It is well accepted that protein deficiency impairs host immunity with particular detriments to the immune system. Insufficient protein intakes result in increased infection rates and morbidity in hospitalized patients (DALY et al., 1990). While your nutrition will certainly be taken care of by some of Australia’s best healthcare professionals if you are hospitalized, if housebound or even simply looking to ensure immune function is not compromised, eating sufficient protein is going to be a factor on your to do list. Due to other benefits of protein such as satiety and muscle sparing effects, dietary intake should start at approximately 1.2g/kg, although this may be greater, or perhaps less depending on your individual circumstances, and it is recommended your consult your coach, dietitian or general practitioner if you would like a more accurate amount.

3. Vitamins and minerals

Vitamins and minerals play nuanced and complex roles in various physiological processes within the human body, and thus will be required in specific doses in order to maintain optimal functioning of both the metabolism and immune systems. Non-perishable foods are the ones most likely to be stockpiled during panic mode, and while they are not necessarily the foods most void of nutrients, they are usually purchased due to the convenience factor, rather than because of their nutritional value. If you face yourself with the executive decision of what to buy, and are faced with options of non-perishable foods, try to opt for those with the higher nutritional value, such as tins of vegetables, fruit salad and legumes, instead of simply stockpiling rice, pasta and frozen pizzas.

Vitamin C

Vitamin C is a water-soluble vitamin and powerful antioxidant and a cofactor for a family of biosynthetic and gene regulatory enzymes. Vitamin C contributes to immune defence by supporting multiple functions in both the innate and adaptive immune system. Vitamin C plays an integral role in upholding epithelial cell integrity by upholding oxidative scavenging activity, thus potentially protecting against environmental stress. Vitamin C accumulates in phagocytic cells (phagocytes are a type of immune cell that protect the body by ingesting harmful foreign bacteria) and assists in the process of microbial killing (Carr and Maggini, 2017). A diet that supplies 100-200mg of vitamin C per day is sufficient in saturating plasma concentrations in healthy individuals and should be sufficient in upholding immune function. Given that vitamin C is water soluble, supplementing with 500mg-1000mg daily during this uncertain time period would most likely be beneficial (Carr and Frei, 1999).

Vitamin D

Vitamin D is a fat soluble vitamin which we can get from direct sunlight, as well as from fortified milk and some fish variants (sardines and mackeral). Vitamin D has been showed to increase immune function, with those who previously experienced vitamin D deficiency benefitting the most. Given that Australia has one of the highest rates of vitamin D deficiencies in the world, a high-quality vitamin D supplement may be beneficial to those looking to bolster their immune systems, as there have been multiple studies associating lower levels of vitamin D with increased risk of infection (Hewison, 1992). 

Deficiency risk factors include:

  • Infants not exposed to sunlight
  • The elderly have less ability to synthesize Vitamin D in the skin
  • Institutionalized people (or quarantined)
  • People with dark skin
  • People who live in cold climates.

Adequate intake is set at 200iu a day for those under 50, with increased doses up to 600iu reccomnded for elderly populations (70+). Given that vitamin D toxicity is highly unlikely to occur with any dosage less than 10,000iu/daily, a high-quality vitamin D supplement could be some low hanging fruit to boost immune function, particularly if one is housebound.  


Zinc is a trace mineral needed for the activity of nearly 100 enzymes, and plays an integral role in our immune system. Zinc may be a tricky one to supplement with, as supplemental doses may decrease the bioavailability of copper in the body (cue Lyndon ominously uttering “for every gimmie, there’s a gotcha”). Furthermore, higher levels of supplementary iron may impact zinc absorption, and thus predispose those taking iron supplements to zinc deficiency. 

It is recommended you consult with your GP or dietitian before taking a zinc supplement, and if you’re looking for whole food sources of increasing zinc levels, oysters and animal meats (particularly red meats) are your best options).

To supplement, 30mg of zinc gluconate, picolinate or carnosine are good options. 

4. Ashwagandha (KSM-66) – 

It is established that elevated periods of cortisol for prolonged periods can have a negative impact on the immune system. Factors which may put you at risk for elevated cortisol include

  • Lack of sleep (Less than 7 hours per night)
  • High amounts of perceived stress
  • High chronic caffeine consumption (which most likely is linked to low calorie sleep)
  • High training volumes

Ashwagandha is a safe and effective adaptogen which can be used to assist decrease stress and serum cortisol.

In one study where the subjects were administered 300mg of ashwagandha root extract daily, the subjects reported a significant decrease in stress assessment scores compared to the placebo group after 60 days of consumption. In addition, the serum cortisol levels were substantially reduced when compared to the placebo group (Chandrasekhar, Kapoor and Anishetty, 2012).  

Although there is need for greater reach on higher dosages, 300mg-900mg seems to be the doses consistent in the literature for getting positive benefits.   


Carr, A. and Frei, B., 1999. Toward a new recommended dietary allowance for vitamin C based on antioxidant and health effects in humans. The American Journal of Clinical Nutrition, 69(6), pp.1086-1107.

Carr, A. and Maggini, S., 2017. Vitamin C and Immune Function. Nutrients, 9(11), p.1211.

Chandrasekhar, K., Kapoor, J. and Anishetty, S., 2012. A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of a high-concentration full-spectrum extract of Ashwagandha root in reducing stress and anxiety in adults. Indian Journal of Psychological Medicine, 34(3), p.255.

DALY, J., REYNOLDS, J., SIGAL, R., SHOU, J. and LIBERMAN, M., 1990. Effect of dietary protein and amino acids on immune function. Critical Care Medicine, 18(Supplement), p.S94.

Hewison, M., 1992. Vitamin D and the immune system. Journal of Endocrinology, 132(2), pp.173-175.

Venkatraman, J. and Pendergast, D., 2002. Effect of Dietary Intake on Immune Function in Athletes. Sports Medicine, 32(5), pp.323-337.


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