How to Actually Build Your Immune System (Not Just "Boost" It)
Everyone's talking about "boosting" their immune system. But boosting implies a quick fix, and your immune system doesn't work like that. It's not a switch you flick with a green juice or an overpriced supplement pack. It's something you build, consistently, through the food you eat, the way you live, and the targeted support you give your body.
As a nutritionist, I want to break this down properly for you, because there is so much noise out there and most of it is trying to sell you something that won't actually do much. Real immune health comes down to five things: getting in the right immune-supporting nutrients through food, reducing chronic inflammation, looking after your gut, nailing your lifestyle foundations, and then adding some extra support on top when you need it.
Let's go through each one.
1. Immune Nutrients
The most important thing you can do for your immune system is make sure it has the raw materials it needs to actually function. That means focusing on:
Vitamin A (liver, ghee, egg yolks), Vitamin C (kiwi, berries, citrus, camu camu), Vitamin D (sunlight, wild-caught fatty fish), Vitamin E (cod liver oil, sunflower seeds, almonds, salmon), Zinc (oysters, red meat, liver, pumpkin seeds), Iron (red meat, spleen, liver), Protein (meat, fish, eggs), and Omega-3s (wild-caught fatty fish like salmon and sardines, or a quality fish oil supplement) — EPA and DHA directly support immune cell function and help regulate the inflammatory response.
These nutrients build and support immune cells. Without them, you're essentially trying to build a house without a foundation.
2. Anti-Inflammatory Support
Chronic inflammation is one of the biggest drains on your immune system. When your body is stuck in a low-grade inflammatory state, your immune resources are constantly being diverted, leaving you more vulnerable to getting sick and slower to recover.
Focus on foods that actively work against inflammation: extra virgin olive oil, wild-caught fatty fish like salmon and sardines, avocado, turmeric, and ginger. A simple habit I love recommending is making a lemon, ginger, and turmeric shot at home. It takes five minutes and your body genuinely feels the difference.
3. Gut Support
Around 70% of your immune system lives in your gut, which means your gut health and your immune health are basically the same conversation. Bone broth, fermented foods, collagen, PHGG, and colostrum are all things I reach for here.
But I also want to say this: if you feel like you're doing everything right and your immune system is still struggling, your gut might need more attention than diet alone can give it. Things like undiagnosed food intolerances, SIBO (small intestinal bacterial overgrowth), bacterial imbalances, low stomach acid, and parasites can all quietly undermine your gut health and by extension your immune resilience. Even thyroid dysfunction can affect gut motility and the diversity of your microbiome, which then loops back and affects immunity. These are things that don't always show up on a standard blood test, and they're exactly the kind of thing I dig into with clients.
A really easy place to start from a food perspective is making a chicken soup using a whole chicken. The bones and skin create a broth that's naturally rich in minerals, gelatin, and collagen, all of which support your gut lining and by extension, your immune system.
4. Lifestyle Foundations
This is the one people want to skip, but honestly it underpins everything else. Your immune system is tightly linked to your nervous system, which means chronic stress, poor sleep, and not moving your body will always catch up with you.
The things that matter most here are sleep, stress regulation, daily movement, eating enough real food, staying hydrated, and breathwork. If you're not doing these consistently, no supplement is going to compensate for it. Start with sleep. It's almost always the highest leverage place to begin.
5. Extra Support
Once the foundations are in place, there are some tools I reach for and recommend to clients when they want to go a bit further. Here's what I'm currently using and why.
Colostrum Pure Premium Powder
Colostrum is the very first milk produced after birth, and it is one of the most impressive immune-supporting substances I know of. This one from Oxymin is collected from the first milking only, within 16 hours of calving, which matters because that's when concentrations of immunoglobulins (IgG, IgA, IgM) and proline-rich polypeptides (PRPs) are at their highest. PRPs are really important because they help regulate immune response. They can both upregulate a sluggish immune system and calm down an overactive one. It's also rich in lactoferrin, a protein that binds to iron and makes it unavailable to pathogens. I add a teaspoon to my morning smoothie or stir it into water (make sure you don’t heat it).
Shop here.
Cell Squared Organic Beef Spleen & Liver
I know, organ meats aren't exactly a glamorous sell, but hear me out. Liver is one of the richest sources of bioavailable vitamin A, and spleen specifically is rich in heme iron - two of the most critical nutrients for immune cell production and function. If you're someone who gets sick often or feels run down constantly, low iron and zinc are usually the first things I'd look at. These capsules are a food-first way to address that without having to actually cook liver every week. Use code RACHEL10 for 10% off.
Shop here.
Cell Squared Ghee
A staple in my kitchen and one of the most underrated immune foods. Ghee is clarified butter, meaning the milk solids are removed, which makes it much easier to digest for people who are dairy-sensitive. What's left is a fat rich in fat-soluble vitamins, particularly A, D, E, and K2, all of which are directly involved in immune regulation. Vitamin A in particular is essential for maintaining the integrity of your mucosal barriers, your gut lining, respiratory tract, and sinuses, which are your body's first line of defence against pathogens. Cook with it, put it in your coffee, or just take a small spoonful. Use code RACHEL10 for 10% off.
Shop here.
PHGG (Partially Hydrolysed Guar Gum)
This one flies under the radar but I recommend it a lot in clinic. PHGG is a prebiotic fibre that feeds the beneficial bacteria in your gut. Since around 70% of your immune system lives there, keeping your microbiome diverse and thriving is one of the most powerful things you can do for immunity. What I love about PHGG is that it's gentle. Unlike some fibres it doesn't cause bloating or cramping, which makes it a great starting point for people with sensitive guts. It also supports the production of short-chain fatty acids like butyrate, which help maintain gut barrier integrity and regulate inflammation. I mix it into water or a smoothie daily.
Shop here.
The Beauty Chef Glow
Glow is a fermented whole food powder, and the fermentation process is what makes it stand out. Fermentation increases the bioavailability of nutrients and creates natural probiotics, so you're getting gut support alongside a solid nutrient profile including vitamin C and zinc, both foundational for immune cell production. There's also a blend of fruits, vegetables, and herbs that are naturally high in antioxidants. I think of it as a daily insurance policy. It's not doing one dramatic thing, it's just quietly supporting all the systems that keep you well.
Shop here.
Sodii Everyday Hydration Salts
Hydration is one of the most overlooked pillars of immune health. When you're even mildly dehydrated, your lymphatic system, which is responsible for moving immune cells around your body and clearing waste, slows right down. Sodii contains sodium, potassium, and magnesium in balanced ratios to actually get water into your cells. I use this most mornings before coffee, and especially if I've been sweating a lot or feeling run down. Proper electrolyte balance also supports your mucosal membranes, which are a physical barrier against viruses and bacteria. Use code RACHELKAY15 for 15% off.
Shop here.
MitoMag
Magnesium deficiency is incredibly common and I see it constantly in clinic. Magnesium is involved in over 300 enzymatic reactions in the body, including the production of glutathione (your body's master antioxidant) and the regulation of inflammatory pathways. When your body is under stress, whether that's emotional stress, illness, or poor sleep, it burns through magnesium fast. Supplementing with a quality form like this helps keep your stress response and immune response from dragging each other down.
Shop here.
Marine Collagen
Your gut lining is your immune system's gatekeeper. When it's compromised, partially digested food particles and pathogens can pass through and trigger chronic immune activation. Marine collagen is rich in glycine and proline, two amino acids that are the building blocks of the proteins that hold your gut lining together. It also supports your mucosal lining more broadly, including in your respiratory tract. I add this to my morning coffee or smoothie and it dissolves completely. You don't even know it's there.
Shop here.
Bone Broth Body Glue
Similar to collagen but in whole food form, which is exactly why I love it. Bone broth is rich in gelatin, collagen, glycine, glutamine, and minerals, all of which support gut lining integrity and immune function. Glutamine is the preferred fuel source for the cells that line your gut, and without enough of it, that barrier starts to break down. The Gevity one is highly concentrated so you get a meaningful dose without having to drink litres of the stuff. Add it to soups, sauces, or just dissolve in hot water.
Shop here but also available at Woolworths.
Ultimate Omega
Omega-3 fatty acids are one of the few supplements I'd recommend to almost everyone, because most people are simply not eating enough oily fish to get adequate EPA and DHA. These two fatty acids are directly involved in immune cell function and in resolving inflammation once your immune system has done its job. That resolution phase is something people don't talk about enough. It's not just about firing up an immune response, it's about your body being able to switch it off again too. I recommend Nordic Naturals because the quality and purity standards are genuinely some of the best in the industry, and the triglyceride form they use is much better absorbed than the ethyl ester form you find in cheaper fish oils.
Shop here.
Turmeric+ Boswellia, Curcumin and White Willow
Turmeric on its own is great, but this formula goes further. The active compound in turmeric is curcumin, one of the most well-researched natural anti-inflammatories out there. What I love about this formula is that it combines turmeric with boswellia and white willow bark, which all work on inflammation through different pathways, meaning you're getting much broader support than a standard turmeric capsule. Black pepper is included too, which is important because curcumin is poorly absorbed on its own and the piperine in black pepper helps your body actually use it. Chronic inflammation is one of the biggest drains on immune function, so this is always going to be worth addressing.
Shop here.
The way I always frame it with clients is: food first, always. These tools work with a good diet, not instead of one. But if you're eating well, you're taking the right things, and you still feel like your immune system is letting you down, something deeper is usually going on.
That's exactly what I work on insideThe Sparkle Method, my 3-month 1:1 program for women who are done guessing and tired of being told everything looks normal. We do a proper deep dive into your symptoms, your health history, your nutrition, your stress, and your pathology using functional optimal ranges, not just "you're in range, you're fine." Then we build a plan that's actually tailored to your body.
If that sounds like what you've been looking for, you can find out more and work with mehere.
Rachel x
This post is for educational purposes only and is not intended as medical advice. Always consult your healthcare practitioner before starting any new supplements, especially if you have an existing health condition or are taking medication.