Heal It - The Immune System and Food We Eat



Does Vitamin C stop us getting a cold?

Vitamin C has many important functions in the body. This powerful antioxidant is needed for healthy skin, cellular repair, iron absorption, nerve conduction & bone structure. Unfortunately though, Vitamin C (nor any vitamin for that matter) will not stop you contracting a common cold. What Vitamin C may contribute to, is a shorter duration and less severe illness by enhancing white blood cell production.


The recommended daily intake of vitamin C is 45mg per day for adults over 18 years old. Kids need a little less at around 40mg per day, but you need more if you’re pregnant (60mg) or breastfeeding (80mg). Citrus fruits are the most well-known source of vitamin C, but what are other top sources in your diet? Here are some comparisons:


1 large orange = 97 mg

1 cup strawberries = 97mg

1 cup broccoli = 81mg

1 kiwifruit = 64mg

1 cup cauliflower = 51mg

1 large potato = 72mg


Vitamin C is degraded by heat and light. Keeping your fruit and veg in a cool dark place will preserve their nutrients for longer and cooking them will reduce the concentration. A quick steam or microwave blanching is the best way to maintain vitamin C, but don't let that stop you adding plenty of veg to a nourishing soup.


Chicken soup boosts the immune system

You might have a favourite chicken soup recipe, handed down through generations, quickly dished up at the slightest sign of sniffle. Home made chicken soup is delicious and as comforting as the sun on a winter’s day. Interestingly, there is evidence to show that chicken soup (made with the whole chicken) can reduce inflammation caused by the cascade of white blood cells (called neutrophils) that happens during a viral respiratory infection. Additionally, chicken contains an amino acid called cysteine. Cysteine has been shown to thin mucus in the lungs making it easier to expectorate and improve breathing.


Of course the other ingredients help too! Onions are really high in quercetin which is an immune boosting polyphenol, and veg such as carrots, potatoes and greens will deliver a punch of vitamins and minerals to get you back on your feet.


Mushrooms and Fungi for the immune system

I have a love for healing power of mushrooms and fungi. I’ve written about it before and I often prescribe a course of medicinal mushrooms in my clinic when the immune system needs a helping hand. Unfortunately, some species such as reishi and cordyceps are not easily accessible for most households. So which mushrooms can you get to boost your immunity?


Dried shiitake mushrooms are easily found in supermarkets these days, and are delicious in soups and stir fries. Consuming around 10g of dried shiitakes daily for four weeks was shown in one study to improve t-cells and reduce inflammation. Furthermore, this paper describes various mushrooms, including shiitakes, with antiviral properties and their potential to support the immune system in combating COVID-19.

Vitamin D for the immune system

Vitamin D is probably best known as a buddy of calcium in keeping your bones strong. Skeletal health is just one function of this fat soluble vitamin. Vitamin D is vital for our immune cells, such as t-cells and b-cells, so they can respond to infection. Vitamin D deficiency has been associated with autoimmune disease and increased infections. Food sources of vitamin D include oily fish, mushrooms that have been exposed to the sun, eggs and liver. However, the best source of vitamin D is sunshine.


People at risk of vitamin D deficiency are those who spend a lot of time indoors, work night shifts, older adults, those with darker skin or cover up for sun safety or cultural reasons. For this reason, a Vitamin D supplement may be necessary to keep at optimum levels.


Zinc for the immune system

We can’t ignore Zinc for the immune system. Zinc is needed for immune cell function, wound healing, reproductive health, thyroid health and even blood clotting. Oysters are packed with it, but if you’re like the rest of my family who can’t stomach the slippery suckers (I love them however), you can get zinc from other seafood, meat and eggs. Zinc deficiency can be serious but easily rectified with good nutrition or supplementation.


Keep a varied diet with lots of colours and textures for your immune system

I’ve heard many times that your plate should be a rainbow of colours. I believe that not only should it be colourful, but also a variety of textures. Keeping a wide selection of whole fruit and vegetables in your diet will undoubtedly boost your vitamin and mineral intake. Having a variety of fibre sources from diverse grains will give a range of B vitamins and minerals such as iron, magnesium and selenium. Grains also contain phytochemicals which can protect against chronic illnesses like cardiovascular disease and diabetes.


Whether it’s a delicious selection of steamed garden veg, a tender piece of salmon, a crunchy freekeh salad, or a plate of sautéed mushrooms on toast, don’t be afraid to let the food on your plate be a piece of your immune system support network.


Next time in Heal It, we’ll learn how sleep (or the lack of it) might be a factor in how often you get sick and how long it takes to recover. Now go and get Grandma’s chicken soup recipe and cook up an immune boosting storm.

 

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