• Chelssie Li

How to REALLY 'boost' immunity: Vol. 2

Updated: Apr 21, 2020

Welcome back to another blog about optimising immunity! If you haven't read volume 1 about the basics of immunity vs lifestyle and how nutrition plays a part, please read my previous post before reading this one.

In this blog post, I'm going to share about different nutrients that play an important part in immune function, as well as foods that are rich in these nutrients.

Remember: Meeting the daily requirements of these nutrients will suffice. Any additional intake will unlikely benefit you further (or very marginally).


1. Vitamin A

Responsible for integrity of cells and mucous formation, women will need 700mcg/day and men 900mcg/day.

Rich food sources: Broccoli, tomato, carrot, sweet potato

NOTE: Vitamin A toxicity could lead to death. If you were to take supplements, double check its vitamin A content and make sure what you're having doesn't exceed 3000mcg/day.

2. Vitamin C

The one that gets too much spotlight. Yes, as an antioxidant, vitamin C deficiency compromises immune function, but we only need about 45mg per day - that's equivalent to half a cup of orange juice!

Studies show that supplementing vitamin C will only show very marginal improvements once a cold is developed (i.e. reduced duration and severity of cold). It doesn't seem to reduce cold incidence, unless if you're constantly under physical stress (e.g. soldiers, athletes, work requiring heavy physical work). It's important to note that this is only shown in people who had low vitamin C levels to begin with.

We can easily obtain vitamin C from our fruits and vegetables, and any excess are excreted via urine as our bodies cannot store vitamin C. If you don't belong to the vulnerable group mentioned above, you don't need to supplement at all - your foods have got your back!

Rich food sources: Strawberries, citrus fruits, broccoli, capsicum, kiwi, brussels sprouts

3. Prebiotics

Prebiotics often hides under the spotlight of probiotics - but in my opinion they're the true heroes. Firstly let's differentiate the two:

Prebiotics: The foods you feed to your gut microbiome for fermentation.

Probiotics: The live microorganisms themselves that does the fermentation

Feeding your gut with good prebiotics means that the good gut bacteria will grow in abundance, and a good profile of gut bacteria is shown to optimise your immune function. Nutrients that are prebiotics include resistance starch and soluble fibre.

Rich food sources: oats, garlic, onion, leek, banana (unripened), cooled pasta, rice and noodles.

4. Zinc

Another nutrient that takes the spotlight! Interestingly, AFTER the onset of a cold, a dosage of ≥75 mg/day of zinc acetate may reduce overall cold duration and some of the symptoms. However, it may not

In adults, zinc acetate doses of ≥75 mg/day taken after the onset of a cold until the cold is gone may reduce overall cold duration and the duration of some symptoms. However, regular zinc supplementation, if you're not deficient to begin with, will not prevent a cold.

Rich food sources: beef, lamb, sunflower seeds, oysters, some cereals (check nutrition content)

Stay tuned for volume 3, where we'll dive into the evidence behind MORE nutrients and their links to immunity!

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