Stay fighting fit by following these eight simple steps.
With the current focus on colds, flu and infections, it seems like the perfect time to talk about eating for immunity. Contrary to popular opinion, eating to boost immune function is not about mega-dosing on vitamin C or drinking nothing but fresh juice. Instead, we should be thinking about optimising our body's ability to fight infections. To do this we need to understand the physiological systems involved in a range of immune responses, and the key nutrients these systems require to be at their best. And this comes down to building some strong dietary and lifestyle habits to help keep you fighting fit and better able to deal with stress or infection when it crosses your path.
The term immunity refers to the body's ability to fight external threats including various micro-organisms and toxins, as well as internal threats that may come from autoimmune responses or the growth of abnormal cells. The body's overall nutritional status, as well as the nutrients we obtain from food, help the immune system to function. Some of the key nutrients involved in immune function are amino acids found in protein-rich foods, a range of essential vitamins and minerals including vitamins A, C and E, selenium and zinc, as well as pro- and prebiotics that help to keep our gut microflora healthy.
Here are eight ways to boost your immunity.
Oysters are a good source of immune-boosting zinc. Photo: Simon Schluter
1. Know the key superfoods
While we often think of foods rich in vitamins to help ward off bugs, many Australian diets don't include enough iron and zinc, two of the key nutrients that directly support immune function. For this reason, if you are a meat-eater, make sure you consume lean meat at least two or three times each week and keep on top of your iron levels.
For those who don't eat meat, adding a daily serve of iron-rich legumes will help to tick this nutrient box, as will opting for wholegrain breads and cereals and eating iron-rich vegetables such as spinach alongside a source of vitamin C. Fruits and vegetables rich in vitamin C include capsicum, tomato and sweet potato. Zinc, too, is important and can be found in meat, shellfish, nuts and seeds including pumpkin seeds or pepitas. Ideally, we need to eat foods rich in zinc every day.
Fermented foods include pickles, yoghurt, kimchi and sauerkraut. Photo: iStock
2. Focus on your gut health
Now, more than ever, we understand the extent to which our gut health affects our overall immune function. The stress of modern life, diets high in processed foods and the regular use of antibiotics have left many of us with guts that function far from optimally.
Working towards better gut balance means including both pro- and prebiotics. Probiotics reintroduce good bacteria to the gut and are typically found in cultured yoghurts, fermented drinks such as kombucha, fermented vegetables such as sauerkraut and kimchi, and supplementary products available in pharmacies.
Prebiotics, on the other hand, pass through the digestive tract undigested and feed good bacteria in the gut. Fibre-rich foods that act as prebiotics include asparagus, Jerusalem artichokes, leeks, onions, beans, chickpeas, lentils and supplementary fibres such as psyllium, pectin and guar gum. Aiming to include both probiotics and prebiotics in your daily diet will help your gut be at its best.
Citrus and kiwifruit are rich in vitamin C. Photo: Katrina Meynink
3. Boost your vitamin C
While there have been links drawn between a high vitamin C intake and a reduction in cold-like symptoms for hundreds of years, unfortunately, there is only a small amount of scientific evidence that proves that a high dose of Vitamin C can reduce the length of a cold once it is present.
Nevertheless, foods rich in vitamin C including oranges, kiwifruit, berries, tomatoes, red capsicums and broccoli, are all rich in antioxidants that offer positive nutritional benefits.
The daily recommended intake of vitamin C is 40 milligrams, but you can safely double this dose, with a daily serve of berries, citrus and kiwifruit to give your body a natural daily vitamin C hit, especially when recovering from an infection.
Arabella Forge's cold-busting chicken soup (see recipe below). Photo: Eddie Jim
4. Try the healing power of soup
Homemade soup is the ultimate immune function superfood. Not only does soup have a high nutrient and water content, those made using chicken bones also have extra immune-related benefits. Research published in the American Journal of Therapeutics found that a molecule identified in chicken soup, carnosine, helped the body's immune system to fight the early stages of flu by inhibiting the migration of infected cells around the body.
So as the temperature drops, get into the habit of cooking up a weekly batch of soup using a bone broth to help supercharge the immune system.
5. Actively limit fast food
Building a strong immune system is not only about what we do eat, but also what we actively choose to avoid. A rise in home-delivered food options means that many of us are eating more fast, processed and fried foods, which will not be doing our immune system any favours.
Research conducted at the University of Bonn in Germany has determined that fast food causes the immune system to react in the same way it does as when it is exposed to bacterial infection. Over time it is believed this leaves us with an increased risk of developing chronic disease conditions including type 2 diabetes. So if you do regularly order in, try to avoid deep-fried options such as fries, spring rolls, curry puffs, schnitzels and fried chicken.
6. Get fussy with your oils
The powerful anti-inflammatory omega 3 fats found in deep sea cold fish have been associated with improved immune function. But it is also worth considering what other oils you may regularly consume that are influencing your immune function.
Vegetable oils contain pro-inflammatory omega 6 fats, which are not so good for immune function. Generally speaking, many processed foods use vegetable oils, meaning commercial sauces, pre-made meals and snack foods may deliver a hearty dose of omega 6 fats.
On the other hand, Australian extra virgin olive oil has an extra high antioxidant content and therefore has the potential to affect immune function positively. So to give your immune system the right mix of good fats each day, the key is to add a couple of tablespoons of extra virgin olive oil to a salad dressing or use it in cooking. Contrary to popular opinion, good quality Australian olive oil can withstand home cooking temperatures without cause for concern. The other key step is to keep your intake of vegetable oil, from spreads, sauces and processed foods as minimal as possible.
Garlic can be taken as capsules or eaten raw. Photo: iStock
7. Try some proven remedies
There are plenty of supplements, pills and potions that claim to boost immune function but hardly any have proven benefits. One of the few options backed by scientific evidence, is garlic. Used to treat bacterial infections, high blood pressure and colds for thousands of years it is the organosulfides (naturally occurring chemicals found in garlic and onions), along with vitamin D help to stimulate the production of the immune cells, macrophages. Garlic can be taken as capsules or eaten raw and get some sunlight each day if you can to enhance its potential benefits.
Echinacea is another of the most commonly recommended herbal remedies for colds and flu. The antiviral and antibacterial herb that originates from America does have some research to support its use in reducing the duration of a common cold. The recommended dose is currently 3g a day. And then there is olive leaf extract, which has both anti-inflammatory and antimicrobial benefits. With double the antioxidant content of green tea, olive leaf extract is another supplement sold for its potential immune-related benefits. While research supporting its use as a specific flu fighter is only in its early stages, it remains a powerful antioxidant supplement with no known side effects.
8. Get back to basics
Dehydration is surprisingly common in Australian adults, especially during cooler weather, when we are not naturally inclined to drink as much cool liquid. Dehydration not only affects your immune system but it is the most common reason bugs tend to stick around when you have been affected. Any type of congestion or a runny nose will be made 100 per cent worse if you are dehydrated, so focusing on drinking plenty of fluids is one of the easiest ways to help your immune system. Plain water, herbal or infused teas or pure vegetable juices are all good choices.
And remember the importance of getting enough rest. It is no coincidence we tend to become unwell when we have been super busy and run down, and most likely not eating well. Sleep and specifically the circadian rhythm have been shown to have a strong regulatory effect on immune function, which means your first port of call when you are not feeling your best is to ramp up the rest.
Susie Burrell is one of Australia's leading dietitians known for her practical, easy-to-understand approach to diet, nutrition and well-being.