Our immune system has the extraordinary job of protecting the body from infectious microbes and other foreign invaders. The immune system is made up of special cells called white blood cells, which include B and T lymphocytes, neutrophils, macrophages and natural killer cells. These immune cells seek out and destroy pathogenic organisms like viruses and bacteria, and inhibit cancer cell growth. White blood cells are made and stored in lymphoid organs throughout the body, i.e. the thymus, spleen, bone marrow and lymph nodes.
A well functioning and balanced immune system is crucial for maintaining good health and prevention of disease. When our immune system is working optimally it can fight off infections effectively and will defends us from cancer and other chronic diseases. However, if there is a problem with how the immune system is functioning, its ability to fight off infections like viruses that cause colds and flu will be affected. This leaves you vulnerable to illness and the development of allergies, autoimmune disorders and chronic diseases like cancer.
A strong functioning immune system is dependent on many factors, including getting adequate sleep and regular exercise, managing stress through meditation and yoga, and most importantly eating a wholesome well-balanced diet. Embracing the wisdom of herbal and nutritional medicine by including immune-strengthening foods and herbs in your daily diet is one of the best ways to bolster your immune defenses to ward off colds and flu and other winter nasties.
Here are some of the best immune-boosting super foods, nutrients and herbs Mother Nature has to offer.
This Face the Current Health Feature is published in Issue 22 / Winter 2019. Order PRINT here, SUBSCRIBE, or continue reading this article below.
Maintaining good gut health is vitally important when it comes to immune health. Not only is the gut our first line of defense against pathogenic microbes, but 80% of our immune cells lie within the gut walls.
We have around 500 different species of bacteria that live in our bodies, a majority of them live in the gut. We need a healthy balance of ‘good’ and ‘bad’ gut bacteria for good health and a strong functioning immune system. Fermented foods such as yogurt, kefir, kvass, miso, kombucha and sauerkraut contain beneficial bacteria that help promote a healthy balance of these beneficial bacteria in the gut. The fermenting process also boosts foods digestibility and nutrient content. Fermented foods have traditionally been apart of most cultures around the world dating back to the Roman times. Including a variety of fermented foods in your diet daily is an excellent way to support immune and gut health and prevent pathogenic bacteria like Candida from flourishing.
Some delicious ways to incorporate more fermented foods into your diet include adding natural yogurt to Bircher or natural muesli, smoothies or salad dressings. Coconut yogurt is a good dairy-free alternative that works well as a topping for healthy pancakes, scones and desserts. The beneficial bacteria present in unpasteurized miso are killed by prolonged cooking at high temperatures, so add miso to soups and other dishes just before removing them from the heat. Try making your own fermented vegetables, they are easy to make and much cheaper than store bought varieties. You only need to add a spoonful of fermented vegetables to salads, curries, dahl, or Buddha bowls to reap their fabulous health benefits.
Garlic has been used as a natural medicine for centuries to support immune health and fight off infections. Garlic contains an active compound called allicin, which gives garlic its super immune stimulating powers. Garlic can help enhance the disease-fighting action of white blood cells. Garlic has been found to reduce the risk of getting a cold or flu, and if you are sick it can reduce the severity of symptoms and will help you recover faster. (1)
Garlic has antibacterial, antiviral and antifungal properties, which makes it beneficial for fighting a variety of infections. Garlic acts like a natural antibiotic with the added benefit of supporting the growth of beneficial gut bacteria, unlike pharmaceutical antibiotics that destroy all of the good and bad bacteria in your gut.
Eating garlic regularly is one of the best ways to protect yourself from colds and flu during the winter months. The way you prepare and cook garlic will affect its health benefits. Allicin is activated when you cut or crush garlic. Heat does destroy some of garlic’s allicin content. Allowing garlic to sit for 10 minutes after cutting will help prevent loss of its medicinal properties when it’s cooked. Eating garlic raw when you can is ideal, added to salad dressings, dips and bruschetta. Garlic is so versatile it can be used in many dishes including pasta sauces, lentil dahls, curries, stir-fries, soups, and homemade garlic bread.
Medicinal mushrooms have been used traditionally in Eastern medicine for thousands of years as an immune tonic. Medicinal mushrooms like shiitake, reishi, maitake, turkey tail, chaga and corydyceps contain incredibly powerful immune-strengthening compounds that help bolster the immune system to improve the body’s ability to fight off infections.
Make sure you buy certified organic mushrooms as they can easily absorb whatever they are grown in, including chemical pesticides and herbicides.
Shiitake and maitake can be enjoyed in soups, stews and stir-fries. Turkey tail, reishi, chaga and cordyceps on the other hand are not ideal for cooking due to their bitter taste and hard woody texture. These mushrooms are best taken as a powder and used to supercharge smoothies, veggie juices, coffee, hot chocolate or chai. Medicinal mushrooms are best consumed over 3-4 months to best enhance immunity.
Medicinal mushrooms contain active compounds called beta-glucans that stimulate the immune system by enhancing macrophage and natural killer function, which play an important role in our immune system (2, 3). Beta-glucans also help the immune system slow down the growth of tumours and protecting the body from cancerous compounds.
Mushrooms are also a rich source of un-digestible fibre called polysaccharides, which act as a prebiotic fibres that act as a food for gut microbiota so they can grow and flourish.
Turkey tail has the added immune benefit of being a prebiotic food that feeds the good gut bacteria.
Chaga mushrooms are classified as an ‘adaptogenic’ food. Adaptogens support the functioning of the adrenal glands and help the body deal with stress in a healthier way. Long-term stress weakens the immune system resulting in you feeling exhausted and more susceptible to illness.
Shiitake mushrooms have been used for centuries in Asia as a food and traditional Chinese medicine, for the treatment of respiratory tract infections and as a Qi (life force) tonic. These immune powerhouses offer plenty in the way of protection against winter nasties, making them a perfect addition to your winter casseroles, stir-fries and soups. Shiitake mushrooms improve the efficiency of the immune system, enhance gut immunity (4), and prevent malignant tumour growth. (5) Shiitake mushrooms are an effective natural antibiotic, killing pathogenic microbes, and leaving beneficial bacteria unharmed. (6)
Brassica vegetables such as kale, broccoli, cauliflower, and Brussel sprouts are high in antioxidant vitamins C and E, carotenoids, sulphur compounds and phytochemicals that all help maintain a strong functioning immune system. Studies have shown that brassica vegetables can stimulate the immune system and decrease the risk of cancer. (7)
Some great ways to enjoy brassicas includes adding raw shredded kale to salads. Massage your kale first for a few minutes with some olive oil and lemon juice to break down its tough fibres. Whole cauliflowers are delicious oven baked covered in spices. Cauliflower also makes a delicious gluten-free pizza base or rice alternative. Toss shredded cabbage through salads, make sauerkraut or healthy coleslaw. Brussel sprouts taste best when they’re pan-fried or roasted with spices and olive oil. Toss collard and mustard greens and arugula through salads for extra flavour.
Bone broths are a wonderful way to give your next winter soup or casserole a nourishing boost. Bone broths contain nutrients and specific compounds that are particularly beneficial for the immune system. Bone marrow contains a compound called alkylglcerols, which is needed to produce white blood cells. This immune boosting lipid has also been found to help inhibit cancer cell growth. You will also find alkylglcerols in mother’s breast milk. Chondroitin sulphate also found in bone broth has anti-inflammatory and immune enhancing properties.
Bone broths also contain collagen and glucosaminoglycans that support gut and immune health by helping seal and heal the gut lining.
Seaweed is a highly nutritious superfood known for their immune boosting properties. Including seaweed in the diet can help increase white blood cell production and reduce the risk of cancer. Seaweed is also rich in minerals, particularly zinc, iron and selenium, which are essential for a strong functioning immune system.
There are many different types of seaweed including kelp, nori, and arame, that can be used to make nori rolls, miso soup, stir-fry’s, and added to fermented veggies. Seaweed flakes are a great way to supercharge pasta sauces and other winter dishes.
Manuka honey, native to New Zealand, is known for its impressive antibacterial properties. Manuka has around 50 times the anti-microbial action compared to other honey varieties. Manuka contains the active compound methylglyoxal that gives this special honey its super antibacterial action.
Certain Manuka bushes contain a ‘Unique Manuka Factor’ (UMF), which is a very effective antibacterial property unique to some Manuka honey. Look for a number from 10-20 after the letters UMF on Manuka honey labels. This will indicate its antibacterial strength. The higher the number, the stronger its action.
Manuka is commonly used for wound healing and sore throats. It’s antibacterial, antiviral, anti-inflammatory and antioxidant properties makes Manuka beneficial for enhancing our immune defenses. Manuka is particularly soothing for sore throats and is delicious added to ginger tea. UMF is heat stable so it won’t be easily destroyed when added to hot drinks.
Turmeric (Curcuma longa) has been a much-loved staple in Asian and Middle Eastern cuisine for thousands of years. Turmeric contains a powerful antioxidant called curcumin, which gives turmeric its anti-inflammatory, anti-cancerous and immune-boosting properties. Studies have shown that curcumin can modulate the activation of immune cells and can enhance antibody responses. (8)
The best way to eat turmeric is raw grated through vegetables, rice or quinoa, in salad dressings, curries and veggie juices. When you mix turmeric with some black pepper it increases curcumin’s absorption significantly.
Ginger (Zingiber officinale) is one of the most popular cooking spices used throughout the world. Ginger has been traditionally used by Chinese herbalists for over 2,500 years to treat colds and flu and digestive problems.
Gingerol is the main bioactive compound found in ginger, which is responsible for much of its immune-boosting benefits. Gingerol has powerful anti-inflammatory, antioxidant and anti-cancerous properties. Ginger also helps support the immune system through its antibacterial action. Ginger is a great addition to winter meals to enhance the body’s ability to fight off respiratory infections.
Adding fresh grated or powdered ginger to your next soup, curry, stir-fry, veggie juice or salad dressing is a delicious way to boost your immunity. Ginger tea is a delicious way to enjoy ginger with some fresh lemon and a little Manuka honey.
Green tea’s immune benefits have been well known for centuries in Eastern cultures. Green tea’s immune boosting effects have been attributed to the presence of high levels of polyphenols, called epigallocatechin gallate (EGCG), which have potent antioxidant, anti-inflammatory and anti-cancerous properties. According to new research these beneficial compounds have the ability to increase the number of T-cells that play a key role in our immune function and suppression of autoimmune disease. (9)
Drinking 3 or more green teas daily can help support healthy immune function.
Berries contain some of the highest levels of antioxidants of all fruit and vegetables, especially those with dark-colored skins such as blueberries, black berries, black current, elderberries and ‘purple berries’ maquai and acai. Their vibrant red, blue and purple colours signify the presence of an important group of antioxidants called anthocyanins, which give berries their anti-cancerous and immune-enhancing properties. Berries are also abundant in immune strengthening vitamin C and A.
Blueberries, raspberries, black berries and strawberries are delicious added to muesli, Bircher, porridge, smoothies and smoothie bowls, yogurt, homemade ice cream, salads, and raw desserts. Dried berries make a tasty addition to trail mixes, and super berry powders (maquai, acai and camu camu) can give your smoothies, veggie juices or bliss balls an added boost.
Citrus fruits such as oranges, lemons, grapefruits and limes are packed with immune boosting vitamins and phytochemicals. Citrus fruits are abundant in vitamin C. This potent antioxidant is one of our most effective immune enhancers, having potent anti-bacterial and anti-viral properties. Immune cells such as T-cells and phagocytes need vitamin C to work optimally to protect us from pathogenic invaders. Vitamin C also supports the functioning of the epithelial barrier of the skin and gastrointestinal tract, against viruses and bacteria. A deficiency in this important vitamin will lead to impaired immunity and a higher susceptibility to colds and flu and other infections.
The flesh and peel of citrus fruits are particularly rich in protective flavonoids that have a strong antioxidant action, which supports the immune system and lowers the risk of cancer. Red and pink grapefruits also provide vitamin A, which has been shown to benefit the immune system and help fight off infections.
Citrus fruits can best be enjoyed on their own or added to breakfast cereals, salads, raw deserts, veggie juices, salad dressings, or squeezed over salads, fish and veggie dishes. Give sweet and savoury dishes an extra immune boost by topping them with citrus zest.
IMMUNE SUPPORTIVE NUTRIENTS
Optimal levels of vitamins A, C, D, and E and minerals iron, zinc and selenium are needed by the body to strengthen our immune defenses and enhance white blood cell production. A deficiency in any of these vital nutrients will lead to impaired immunity and an increased vulnerability to colds and flu and other infections. A deficiency in these vitamins and minerals will also increase your risk of developing chronic diseases such as cancer. Low vitamin D levels are also associated with the development of autoimmune diseases. Some of the best sources of these immune-boosting vitamins and minerals are citrus fruits, berries and kiwi (vitamin C); cod liver oil and egg yolk (vitamin D); olive oil and avocados (vitamin E); red meat and lentils (iron); fish, nuts and seeds (zinc); and Brazil nuts (selenium).
IMMUNE ENHANCING BOTANICALS
There are a wide variety of highly effective herbs used by herbalists and naturopaths to help strengthen and regulate the immune system.
Echinacea (Echinacea purpurea) is one of the most widely known immune-stimulating herbs commonly prescribed for colds and flu and other infections. Echinacea increases the production of white blood cells and stimulates the overall activity of the immune system, making it more efficient at fighting bacteria and viruses. Echinacea should be taken as soon as cold and flu symptoms start and continued until symptoms subside.
Andrographis (androgaphis paniculata) is a traditional Chinese and Ayurvedic medicine that is also known as ‘Indian Echinacea.’ Andrographis is another excellent immune-stimulating herb that is beneficial for treating acute infections. This herb is best taken in the initial stages of an infection, then continued for the duration of the illness. Immune stimulates like these are generally only used short-term.
Astragalus (astragalus propinquus), Ashwagandha (withania somnifer), Siberian ginseng (Eleutherococcus senticosus), Liquorice (glycyrrhiza glabra) and Schisandra (Schisandra chinensis) are all immune-modulating herbs. These herbs help regulate the immune system. They boost immune responses when the immune system is running below par, and calms it down if it is overacting, like in the case of autoimmune diseases and allergies. Immune-modulating herbs can be taken daily and used long-term. They have a balancing rather than stimulating effect on the body. These herbs are recommended for people who get frequent infections or autoimmune diseases.
Elderberry and Elderflower (Sambucus nigra) are two immune tonic herbs that can be taken long-term to build and strengthen the immune system. These herbs are also suitable to use long-term for people with poor immunity.
The best way to protect yourself this winter from colds and flu and other infections is to start incorporating a variety of these super immune-strengthening foods and herbs into your daily diet. Start experimenting in the kitchen with new nourishing recipes and herbal teas that use these healthful ingredients. You should always try were you can to get all of your nutrients through wholefoods, however nutritional supplements can be extremely beneficial to complement a healthy diet. Nutritional supplements can help correct any nutritional deficiencies and will ensure that you are getting optimal levels of all the crucial immune-boosting vitamins and minerals you need for a strong functioning immune system.
Lisa Guy is a well-respected Australian naturopath, author and passionate foodie, with over 18 years clinical experience. Lisa runs a naturopathic clinic called ‘Art of Healing’ and is an avid health writer and recipe developer for leading publications. Lisa is also the founder of Bodhi Organic Tea, an award winning herbal tea company who makes beautiful unique tea blends all naturopathically blended to enhance health and wellbeing.
- P, et al. Preventing the common cold with a garlic supplement: a double-blind, placebo-controlled survey. Adv Ther. 2001 Jul-Aug;18(4):189-93.
- Akramiene D, et al. Effects of beta-glucans on the immune system. Medicina (Kaunas). 2007;43(8):597-606.
- Deng G, et al. A phase I/II trial of a polysaccharide extract from Grifola frondosa (Maitake mushroom) in breast cancer patients: immunological effects. J Cancer Res Clin Oncol. 2009 Sep;135(9):1215-21.
- Dai X, et al. Consuming Lentinula edodes (Shiitake) Mushrooms Daily Improves Human Immunity: A Randomized Dietary Intervention in Healthy Young Adults. J Am Coll Nutri. 2015;34(6):478-87.
- Fang N, et al. Inhibition of growth and induction of apoptosis in human cancer cell lines by an ethyl acetate fraction from shiitake mushrooms. J Altern Complement Med. 2006 Mar;12(2):125-32.
- Ciric L, et al. In vitro assessment of shiitake mushroom (Lentinula edodes) extract for its antigingivitis activity. J Biomed Biotechnol. 2011;2011:507908.
- Kapusta-Duch J et al. The beneficial effects of Brassica vegetables on human health. Rocz Panstw Zakl Hig. 2012;63(4):389-95.
- Jagetia GC, Aggarwal BB. “Spicing up” of the immune system by curcumin. J Clin Immunol. 2007 Jan;27(1):19-35. Epub 2007 Jan 9.
- Ngoc B. Huynh. The Immunological Benefits of Green Tea (Camellia sinensis) International Journal of Biology; Vol. 9, No. 1; 2017