You probably aren’t thinking about colds and flu when you’re packing your lunch, cooking dinner or gulping a smoothie after yoga class. But the foods you eat can have a powerful effect on your body’s ability to ward off everyday bugs, whether it’s the office cold everyone’s passing around or germs from the person coughing on the mat next to you in class.
“Boosting your intake of fruit and vegetables could be the best defence against winter sniffles and sneezes,” says accredited practising dietitian Denise Griffiths, from the faculty of health services at Curtin University in Perth. “There’s no silver bullet for a healthy immune system, but the idea is to eat a wide variety of fruit and vegies in a range of colours each day, and to choose those in season,” she says. What’s more, a healthy immune system isn’t important just in cold season; evidence suggests that it can help protect you from a host of chronic diseases as well.
The following 10 foods are must-haves in an immunity-boosting diet. They all contain key nutrients that have a demonstrable effect on the body’s ability to stay healthy, and they’re delicious and convenient, too. In fact, you probably have some of them in your kitchen already. Add them to your weekly menu and be well.
Strawberries: Immunity Boost
WHY: Among commonly consumed berries, strawberries have the most vitamin C, which can help you ward off illness. “Vitamin C, or ascorbic acid, helps the body to fight infection at the level of the cells,” says Griffiths. She adds that vitamin C has been shown to reduce the severity of symptoms associated with colds. Vitamin C is also involved in making the collagen necessary for maintaining healthy skin, which is a front-line defender against viruses.
GOOD TO KNOW: When frozen, strawberries retain most of their vitamin C, so you can enjoy them all year.
USE: Strawberries are equally at home in your favourite breakfast bowl, in a spinach salad with sliced almonds, in fruit salsas or in fresh fruit smoothies like the one below.
1 cup (250ml) almond milk*
1 cup (250ml) coconut milk
1 cup (130g) strawberries, hulled
1 frozen banana, roughly chopped
½ green apple, cored, finely diced
1. Place all the ingredients in the jug of a blender and blend until combined and smooth.
2. If the smoothie is too thick, add more almond milk or water and blend until it reaches the desired consistency. If the smoothie is too thin, add a little more banana or some natural yoghurt.
* Almond milk is made from ground almonds and contains no lactose or cholesterol. Available from health food shops and some supermarkets.
WHY: You might be surprised to know that, gram for gram, cavalo nero (also sold as “kale”) is a richer source of beta-carotene than carrots or sweet potatoes, which makes it a top choice for fighting off colds and the flu. In the body, the liver converts beta-carotene into vitamin A, which amps up the immune system by increasing the production of white blood cells, including ones that seek out and destroy foreign bacteria and viruses. “Vitamin A is essential for the immune system to function normally,” says Griffiths. Vitamin A also helps maintain the lining of your respiratory and digestive tracts, which are your first lines of defence against pathogens. This robust leafy green also has high levels of vitamin C, an antioxidant that’s important for immune function.
GOOD TO KNOW: Conventionally grown cavalo nero can contain high levels of pesticide residues, so choose organic whenever possible.
USE: Fat-soluble beta-carotene is better absorbed when it’s in the presence of dietary fat, so try gently frying cavalo nero (see below), including it raw in salads with diced avocado or making crispy chips.
Sesame cavalo nero
Serves 4 as a side
1 bunch cavalo nero
1 tsp olive oil
1 tsp sesame oil
1 garlic clove, crushed
2 tbs tamari
1-2 tbs sesame seeds, toasted
1. Wash cavalo nero and remove tough stems. Slice the leaves widthways into 2-3cm pieces.
2. In a large frying pan or wok, heat the combined oils over medium-high heat. Add cavalo nero and fry for 1-2 minutes. Add garlic and cook for a further minute. Add tamari and 2 tablespoons water, cover and steam until cavalo nero is wilted. You may need to add a little more water.
3. Sprinkle with sesame seeds and serve.
WHY: Full of live probiotic bacteria, this tangy dairy product is made by inoculating milk with a mixture of yeasts and bacteria. These beneficial micro-organisms take up residence in the intestines, where they alter the pH of the intestinal environment to a level that is unfavourable to harmful microbes. Probiotics are also thought to play a direct role in immune cell function and may even reduce the incidence, severity and duration of symptoms associated with the common cold.
GOOD TO KNOW: Kefir and yoghurt are both cultured dairy products; the difference is that yoghurt is made by inoculating milk with bacteria, while kefir is inoculated with a blend of yeasts and bacteria and has more beneficial probiotics that can colonise the intestinal tract.
USE: Buy plain kefir and layer it with strawberries and nuts; blend it into smoothies; or whisk it with olive oil, lemon juice and crushed garlic to make a creamy salad dressing.
WHY: Start your day with a comforting bowl of oatmeal and build immunity from the get-go. Wholegrain oats contain beta-glucan, a compound shown to activate immune cells that fight infectious micro-organisms. Oats are also a source of immunity-building zinc. For the most benefit, choose rolled oats rather than sugary instant varieties.
GOOD TO KNOW: No time to make oats in the morning? You can soak them overnight with an equal amount of liquid (milk, water or apple juice, for example). In the morning, add nuts, seeds, fruit or yoghurt. If you have a little more time and want a hot breakfast, cook equal parts of oats and liquid for 10-15 minutes.
USE: Grind rolled oats in a food processor and substitute it for part of the flour in muffins, pancakes and scones, or mix rolled oats with dried fruit, nuts and pumpkin seeds for an immunity-building muesli to eat with yoghurt or kefir.
Black bean & Oat Burgers
400g can black beans, drained, rinsed
2 cups diced mushrooms
1 cup (90g) rolled oats
1 garlic clove
1 tbs cumin
1 carrot, grated
1 CUP coriander leaves, chopped
1 tbs olive oil
6 wholemeal hamburger buns
2 tomatoes, sliced
Baby spinach, to serve
Tomato salsa or chutney (optional), to serve
1. Place half the beans in a food processor. Add the mushrooms, half the rolled oats, garlic, egg and cumin and process until well combined.
2. Transfer mixture to a large bowl. Add remaining beans and oats, carrot and coriander and stir until well combined. Shape into 6 equal patties.
3. Heat oil in a large frying pan over medium-high heat. Cook patties, in 2 batches if necessary, on each side until browned.
4. Place patties on buns with tomato and baby spinach. Serve with tomato salsa or chutney, if desired.
WHY: Rich, velvety almond butter contains three times as much vitamin E as peanut butter. “Vitamin E is a potent antioxidant that protects all the body’s cells from oxidation [damage] and it’s also a great anti-inflammatory that helps balance the immune system response,” says naturopath and nutritionist Sonja Barnes at Nature Care College in Sydney.
GOOD TO KNOW: Available from health food stores and some supermarkets, almond butter is also a good source of heart-healthy monounsaturated fat.
USE: Make an almond butter sandwich with apple slices and honey; mix a dollop with coconut milk and red curry paste to make a dipping sauce for grilled vegies; or blend a spoonful into a smoothie.
WHY: This ceremonial Japanese tea is produced when young green tea leaves are steamed and then ground into a fine bright-green powder. Scientists at the University of Colorado discovered that, because the whole leaf is consumed in the tea, matcha provides sky-high levels of a class of antioxidants called catechins, which studies suggest can help halt the replication of the influenza virus and stimulate immune cells. Matcha has a lush vegetal flavour with a lingering sweetness.
GOOD TO KNOW: Besides mixing powdered matcha with hot water, you can add it to smoothies, steamed milk or soy milk, and even incorporate it into baked goods.
USE: Place a teaspoon in a small bowl or mug and add a few inches of simmering water. Whisk briskly and top with additional hot water to desired taste.
WHY: One of nature’s most perfect foods, this staple protein is high in soluble fibre, which has been found by University of Illinois scientists to increase the production of an anti-inflammatory protein that strengthens the immune system. Beans also have an abundance of immunity-boosting antioxidants and folate, a B vitamin required for the production of new immune cells.
GOOD TO KNOW: All beans are good sources of soluble fibre, but lima beans and kidney beans contain the most.
USE: Beans are as versatile as they are nutritious, starring in soups, stews, dips and salads. For a nearly instant lunch, fold cooked beans, chopped tomato, rocket and a squeeze of lime juice into a wholegrain tortilla.
WHY: Lauded for its nutty taste and chewy texture, this heirloom rice was called “forbidden rice” in ancient China because it was reserved for royalty and nobility. Louisiana State University Agricultural Center scientists working in the food science department discovered that black rice contains especially high levels of antioxidants (including the same anthocyanins as blueberries), which protect immune cells from oxidative damage.
GOOD TO KNOW: An increasing number of health food stores and supermarkets now carry this once-rare rice variety.
USE: For a tasty main-dish salad, toss cooked black rice with dried cherries, pecans, chopped red capsicum, baby spinach and olive oil.
WHY: Fortified with vitamin D, milk is one of the few reliable dietary sources of the sunshine vitamin. T cells, the immune system’s virus-killing cells, rely on vitamin D in order to become active when viral threats abound. According to a study involving nearly 19,000 subjects in the Archives of Internal Medicine, people with the lowest average levels of vitamin D were 36 per cent more likely to develop an upper-respiratory infection than those with higher blood levels of the vitamin.
GOOD TO KNOW: A study in the Journal of Nutrition discovered that whey, a protein in dairy products, can propel immune cells into action.
USE: Stir into oatmeal or muesli, add to smoothies or drink warm with a dash of ground cinnamon.
WHY: Pumpkin seeds, which you can buy hulled in supermarkets, are brimming with the mineral zinc, which can help you fight colds and flu. Zinc plays a central role in immune function by increasing the production of various immune cells that are involved in the body’s response to viruses. “A review of a large number of studies concluded that zinc given within 24 hours of the onset of symptoms reduced the duration and severity of colds,” says Griffiths, adding that it’s best to get zinc from food rather than a supplement.
GOOD TO KNOW: Store pumpkin seeds, also known as pepitas, in the freezer to keep them fresh.
USE: Add to muesli and top with yoghurt or kefir; use in pesto instead of pine nuts; or toast in a dry frying pan with sea salt and sprinkle over soups, salads and roasted root vegetables.
Matthew Kadey is a dietician who dedicates most of the space in his community garden to cavalo nero.