Optimise your immunity and protection against disease with evidence-based nutrition science.
In a climate of COVID outbreaks and vaccination queues, it’s little wonder that there is heightened interest in dietary measures to boost immunity and protect against sickness, from colds and flu to COVID-19. But while the internet is brimming with tips, from special herbal tea blends to specific food inclusions and exclusions, a lot of advice is based on myths and a motley patchwork of semi-facts rather than scientific evidence. The bad news is that, unfortunately, there is no specified diet to enhance protection against illness. This is, in part, due to the fact that nutrition is only part of the picture when it comes to immune function (most of us know that when we become overtired or over-stressed, or ‘run down’, we tend to encounter more illness). On the flip side, there are certain foods and food constituents that can, in synergy with other lifestyle measures such as adequate sleep, help to stave off infection and disease.
How foods support immune function
Consuming adequate nutrients as part of a balanced diet is a foundation for healthy function of cells, including immune cells, which guard against microbial attacks and can help to prevent or mitigate excess inflammation that could lead to disease or illness. Each stage of the body’s immune response depends on the presence of various micronutrients. Examples of nutrients that have been found to promote the growth and function of immune cells include vitamin C, vitamin D, zinc, selenium, iron, and protein. Another important consideration is supporting good gut bacteria with nutrients such as fibre. Some 70 per cent of the immune system comes from the gut, so supporting good gut bacteria with dietary habits such as consuming 25 to 30 grams of fibre per day can help to support immune function (if your fibre intake is minimal, build up gradually by adding a piece of fruit a day to avoid gas and constipation). Some research also supports a case for including pre- and probiotic foods to cultivate optimal gut bacteria. This has been discussed especially in relation to practices such as taking antibiotics, which can deplete good gut bacteria and promote bacterial imbalance.
Immunity nutrition mistakes
Just as immune function can be positively influenced by consumption of nutrient-dense foods, diets consisting primarily of highly-processed foods and lacking in minimally processed foods can negatively affect a healthy immune system. A diet high in refined sugar and red meat and lacking fruit and vegetables may also work against healthy gut bacteria and potentially contribute to chronic gut inflammation - which can negatively impact immune function.
Immunity foods menu
Prioritise plant-based foods such as vegetables, fruits, legumes, whole grains, nuts and seeds and aim to include loads of colour (generally speaking, richly-coloured plant foods are high in desirable nutrients). The Mediterranean diet is a good guide. As well as a wealth of immune-supporting vitamins and minerals, these ingredients contribute fibre, which promotes growth of good gut bacteria.
- Whole grains and cereals
- Lean meats, poultry, fish, eggs, tofu and legumes
- Nuts, seeds and unsaturated oils
- Dairy products or non-dairy alternatives
Lifestyle factors to optimise immunity
To optimise the effect of an immune-supporting diet, attend to these protective lifestyle factors.
- Eat a balanced diet including whole fruits, vegetables, lean proteins and whole grains and maintain adequate hydration (primarily with water).
- Don’t smoke.
- Moderate or avoid alcohol consumption.
- Undertake moderate regular exercise.
- Aim for seven to nine hours of good-quality sleep each night. Try to keep to a regular sleep schedule, waking up and going to bed around the same time each day.
- Manage stress. Find strategies that work with your interests and lifestyle—from exercise to meditation or a creative hobby such as playing music, practising art or cooking.
- Wash and/or sanitise hands throughout the day. This is particularly important after being outdoors, after being in public places, before and after preparing and eating food, after using the toilet and after coughing or blowing your nose.
If you suspect that your immune function is sub-optimal or you would like to ensure that your diet supports optimal protection against illness, consider consulting an accredited practising dietitian (APD), who can equip you with knowledge and practical tips for meeting your health goals.