Nutrients for immune health

Your immune system is a remarkable defence mechanism that protects your body from multiple threats, such as coughs, colds, and various infections. Moreover, it plays a critical role in distinguishing between harmful invaders and our own cells. However, in cases where the immune system malfunctions, it can mistakenly attack and harm the body's own cells and tissues, leading to autoimmunity.

A well-balanced diet plays a crucial role in supporting immune health by providing essential nutrients that help strengthen the body's defence mechanisms, reduce inflammation and support tissue repair. 

Antioxidants - Eat the Rainbow! 

Antioxidant vitamins and minerals such as vitamin C, beta carotene (provitamin A), zinc and selenium play a crucial role in supporting immune function by protecting cells from free radicals - a type of unstable molecules produced in the body which can damage cells and impact immune health. 

Antioxidants help neutralise and stabilise free radicals, safeguarding immune function and reducing the risk of chronic diseases. The body produces antioxidants naturally but they can be obtained from colourful foods like berries, colourful fruits, dark leafy greens, nuts, and seeds. 

Additionally, herbs and spices like turmeric, ginger, and cinnamon are also great sources of antioxidants that can be easily incorporated into meals.

Vitamin C
In addition to its antioxidant benefits, Vitamin C is important for the development and function of white blood cells, which are critical components of the immune system. It is also required for the synthesis of collagen, which helps maintain the structure and strength of our epithelial barriers, such as the skin and gut lining. These barriers act as a protective layer against pathogens, helping to keep them out of the body and reduce the risk of infection.

While vitamin C has been widely used as a remedy for the common cold, research indicates that it does not significantly reduce the likelihood of catching a cold for most individuals - unless you have low vitamin C intake in the first place. However, regular intake of vitamin C supplements may slightly shorten the duration of colds or mitigate symptoms to some extent if you do catch a cold. 

The NHS recommends adults get 40 mg of Vitamin C daily, a dose that prevents scurvy from developing (a disease caused by a Vitamin C deficiency). Considering the evidence from various types of studies, including how the body processes vitamin C and its effects on health, we conclude that a daily intake of 200 mg of vitamin C is optimal for most adults. 

If you do get an infection, your Vitamin C levels can be affected, which can lead to increased inflammation and a higher demand for Vitamin C in our body. However, please note that taking excessive amounts of vitamin C through supplements can result in unwanted side effects such as diarrhoea or gastrointestinal discomfort. Taking less than 1,000mg of vitamin C a day is unlikely to cause any harm. Speak to your doctor if you are unsure. 

Here’s how to get your Vitamin C fix: 

  • Oranges (1 medium-sized): Approximately 70mg
  • Strawberries (1 cup): Approximately 85mg
  • Kiwi (1 medium-sized): Approximately 70mg
  • Red Bell Peppers (1 medium-sized): Approximately 150mg
  • Spinach (1 cup, cooked): Approximately 10mg

Factors such as pollution, smoking, infections, and diseases with inflammation contribute to increased needs for Vitamin C. If you do smoke, add an additional 35 mg to your daily dose.  
Vitamin A 

Vitamin A plays other various roles in immune responses, including innate immunity, antibody production, and the development and functionality of immune cells. 

The daily amount of vitamin A needed by adults is:

  • 700 µg a day for men
  • 600 µg a day for women

It can be obtained from the diet in different forms: 

Preformed vitamin A is found in animal-based foods like liver, eggs, and dairy products. Liver is an excellent source of preformed vitamin A. A 100-gram serving can provide more than the daily requirement* 

β-carotene, a precursor of vitamin A, is present in plant-based sources like carrots, spinach, and sweet potatoes. One whole sweet potato, including its skin, provides an impressive 1400 mcg of vitamin A. This amount exceeds 150% of your daily requirement for vitamin A in just a single serving! 

* During pregnancy, it is important to exercise caution with vitamin A intake by avoiding excessive consumption of liver or high-dose vitamin A supplements, as they can potentially pose risks to the developing foetus.

Zinc

Zinc is crucial for immune function, aiding in cell development, antibody production, and inflammation regulation. A deficiency in zinc can weaken the immune system, increasing your vulnerability to infections. 

In addition, some studies have shown that low levels of zinc in the blood are associated with autoimmune diseases like multiple sclerosis (MS) and rheumatoid arthritis (RA). In fact, a large analysis of the research consistently showed that individuals with autoimmune disorders have lower levels of zinc in their blood compared to healthy individuals.

For adult men, the RDA is 9.5 mg per day, while for adult women, the RDA is 7 mg per day. However, if you are plant-based it is recommended you consume approximately 50% more zinc to compensate for lower absorption of zinc from plant-based foods. A study published in CMAJ showed that supplementing with zinc for 5-7 days upon the onset of symptoms was effective in reducing the duration of a cold. 

Zinc-rich foods:

Certain animal foods are high in zinc, such as oysters, beef, lamb, poultry, shellfish. Vegans can obtains zinc from legumes (like chickpeas and lentils), nuts, seeds (such as pumpkin seeds), and whole grains (like quinoa and brown rice). However, it may be a little trickier to obtain sufficient amounts so careful dietary planning is key. 

Include seeds and nuts: Snack on zinc-rich seeds and nuts like pumpkin seeds, cashews, almonds, and pine nuts. They not only provide zinc but also offer other nutritional benefits.

Eat more legumes: Legumes such as chickpeas, lentils, and beans are a good source of zinc. Add them to soups, salads, stews, or enjoy them as a side dish.

Selenium 

Selenium is an essential trace mineral that plays a crucial role in supporting immune health, acting as an antioxidant and also promotes the production of antibodies, which are vital for the body's immune response against pathogens.

The daily requirement for selenium is 75 µg for adult males and 60 µg for adult females. 

Brazil nuts are known for their high selenium content. On average, one Brazil nut contains approximately 68-91 micrograms (mcg) of selenium. Other good dietary sources of selenium include seafood (such as tuna, sardines, and shrimp), poultry (such as chicken and turkey), eggs, mushrooms, whole grains, and dairy products.

Vitamin D 

Vitamin D has been found to have a positive effect on our immune system, stimulating immune cells to multiply and enhance their ability to move towards infection sites and improve their ability to engulf and destroy invading microbes like bacteria, viruses, and fungi. 

Studies show that adequate vitamin D reduces the risk of acute respiratory tract infections, flu and COVID 19, and autoimmune diseases such as Rheumatoid Arthritis.  

To ensure adequate vitamin D intake in the UK, it is recommended to expose your skin to sunlight during the summer months, consume vitamin D-rich foods such as oily fish, eggs, and fortified dairy products. Ths NHS recommends all adults should take a vitamin D supplement of 400 IU (or 10 µg) during the winter months or all year round if sunlight exposure is limited.

Omega 3 fats

Omega-3 fatty acids, specifically in the forms of EPA and DHA, help regulate the inflammatory response, which is important for immune health, and promote a more balanced immune response, and may help in reducing the risk of autoimmune diseases. 

Eat fatty fish: Include fatty fish like salmon, mackerel, sardines, trout, and tuna in your meals. 
Incorporate flax seeds and chia seeds: Add ground flaxseeds or chia seeds to your smoothies, yoghurt, oatmeal, or baked goods. 
Include walnuts: Snack on walnuts or add them to salads, cereals, or baked goods. 

Try fish oil based or algae-based supplements which provide minimum 250g - 500mg of combined EPA and DHA daily. 
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