How to boost your immune system

What is an immune system?

Your immune system is designed to protect your body against infections (bacteria, viruses, parasites etc).

The immune system is made up of two different parts:

  • The innate immune system
  • The adaptive immune system

The innate immune system is like your first line of defense. It’s a non-specific guard against all potential invaders. For example, your skin is a physical barrier which prevents pathogens getting in and when you cut your self you increase your risk of infection as pathogens have a way of getting in. There are lots of different parts of the innate immune system, tears, saliva, stomach acid, and special cells like neutrophils, macrophages and natural killer cells.

The adaptive immune system is the second line of defense and they are specific – in that they recognise specific pathogens and kill those in a targeted response. B and T cells are the main cells involved in this. If the pathogen is new to the body, it can take some time for specific B and T cells to be created to recognise that particular pathogen and create the army needed to remove it from the body. But if it’s the second or third time the body has been exposed to that particular pathogen then the B and T cell army can act very rapidly – which is why, for many illnesses you only get sick from it once.

What parts of my body are involved in immunity? (in brief)

  • Skin – a physical barrier against all pathogens
  • Bone marrow – all blood cells and immune cells are made in the bone marrow.
  • Lymph nodes – are all over our body and act as a filter for all pathogens.
  • Spleen – filters the blood – it gets rid of old blood cells and stores cells involved in our immune response

What can I do to prevent myself from getting sick?

You need a healthy immune system to protect you from bugs that can make you sick. And if you do get sick, you want your immune system to be able to sort it out for you, as quickly as possible. We can help our immune system out by doing a few thing, every day, to keep it at optimum function.

A healthy diet and lifestyle is key to building a strong immune system.

BUT there is no one magic pill, supplement, food or diet that will save you from getting sick, including from Covid-19.

It’s also important to note that some medications and medical conditions can reduce people’s immunity and make them more at risk of getting sick, regardless of their diet or lifestyle choices.

We also need to remember that each of us, at different times of our lives, have different access to healthy foods and services that help us stay well. Often, these things are not in our control – during a pandemic, for example!

To optimise your immune function:

  • Eat a wide variety of plant foods. Aim for 50% of your diet to be fruit and vegetables. Pick a range of different colours every day to ensure you get a variety of vitamins, anti-oxidants, carotenoids and minerals.
  • Choose plenty of whole foods such as: oats, rice, potatoes, kumara, nuts, seeds, legumes, quinoa, eggs, meat, fish, full fat dairy, – these provide lots of protein, fibre, iron, niacin, calcium, zinc and folic acid.
  • Ensure you are well rested – aim for 7 to 8 hours sleep every night.
  • Move your body in ways you enjoy. Aim for 1 hour movement, most days.
  • Relax! High levels of stress can weaken your immune system – meaning you are more likely to get sick when you are stressed. Do things to relax you every day: laugh, meditate, listen to music, take time out.
  • Wash your hands and don’t touch your face!
  • If you smoke, stop.
  • Aim to have 3 to 5 alcohol free days a week and stick to 1 to 2 standard drinks in one sitting.
  • Drink plenty of water and other fluids
  • If you are sick, stay home and try and reduce your exposure to others that are sick.

There is some evidence that a typical “Western diet”, high in ultra processed foods and take-away’s, can affect our immune response. It is thought that our body see’s these types of foods as a threat and can trigger inflammation. A study in mice, showed epigenetic changes in white blood cells – or in other words, changes to our genetically programmed immune response – causing our immune system to react more strongly. Thus, driving inflammation and possibly driving inflammation based diseases such as cardiovascular disease.

Do I need supplements?

Some supplements may help your immune system, but they are not a magic instant fix. Following basic lifestyle advice, as above, is more important, but supplements can be part of that picture and may be helpful.

Vitamin C

Vitamin C helps your skin integrity and helps to make immune cells.

The evidence for taking vitamin c is not overwhelming. Generally, you need to be taking vitamin c before you get sick and it won’t prevent you from getting unwell either. It may reduce the length of time you are sick for by around half a day. Vitamin c supplements may be more helpful for people who have a lot of physical stress, such as athletes and soldiers.

If you did want to supplement you could try doses between 200mg up to 2000mg/day. Doses over 2000mg can cause diarrohea and stomach pain. Vitamin c is a water soluble vitamin, meaning that any vitamin c that your body doesn’t need is excreted through your urine. So it can be just expensive wees.


Zinc has a lot of roles in the body, especially with our immune system. Zinc has been shown to be helpful in preventing illness and reducing symptoms and the length of time you are sick for. Zinc is readily available in many foods such as: meat, legumes, grains, nuts, seeds, eggs and dairy.

Zinc acetate in doses around 75mg/day can reduce how long you are sick for and reduce some of the symptoms. In kiddies taking 10 to 15mg/day of zinc before getting sick may reduce the amount of times they get a cold. Zinc can be toxic if you take too much, so if you notice, loss of smell, nausea, vomiting, stomach cramps then stop supplementing immediately.


Probiotics are good bugs that may help your immune system and there is some evidence that probiotics can reduce the risk of upper respiratory infections. But there are hundreds of different types of probiotics and different combinations, so it’s pretty difficult to figure out which strains are helpful and in which combinations – and then to figure out which product on the market has that right strain. There is also some evidence that taking probiotics before and after getting the flu vaccine can help that work more effectively. The results for taking probiotics aren’t strong. If you want to take a probiotic and find them useful, then do so as they certainly won’t cause harm. There are some oral probiotic lozenges, which may help prevent throat infections, Streptococcus salivarius is the probiotic agent. These may be helpful in repopulating the throat with beneficial bacteria.

Vitamin D

Vitamin D helps regulate immune cells during an infection. Studies have shown a link between low vitamin D levels and a higher risk of infections in the upper respiratory tract. Vitamin D may help prevent respiratory infections,

There are not many food sources of vitamin D and generally 80% of our vitamin D is obtained from the sun. You only need 1/4 of the time it takes to get burnt, to make enough vitamin d. Those with darker skin will need more sunshine, than those with paler skin. In winter, a vitamin d supplement may be a good idea, especially if you work in doors, live in colder climates and/or have darker skin.


There’s not a lot of evidence to support using echinacea to reduce colds and flu and it can interact with certain medications, especially immune suppressive drugs. Echinacea may be helpful in preventing and reducing severity of upper respiratory tract infections, in a limited way.

Moral of the Story?

Our immune system is complex and we need a wide variety of whole foods, rest, exercise, sleep, plus good hygiene practices to ensure our immune system functions well. There is no magic pill that creates the perfect immune system and we do need to look at this more holistically. You don’t need supplements to have a healthy immune system, but if you want to take them, be aware of upper limits to avoid any nasty side effects. Vitamin D supplementation is likely the most useful in the winter months especially for those living in the South island and/or those with darker skin.

Got any questions? Want to book an appointment for individualised advice, just for you? Get in touch. I have online appointments available and resource guides that will suit your nutrition needs and budget.

One Comment Add yours

  1. oneanna65 says:

    Reblogged this on cancer killing recipe and commented:
    Be healthy and save.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s