Diet and Immunity
As the colder weather approaches, people seek ways to protect themselves from flu or illness. Often you may see ads with sensationalist headlines about ‘immune boosting’ foods or supplements, with companies promising a magic pill or food supplement to keep you healthy. While it can be easy to fall for this marketing to keep yourself healthy, the reality is there is no supplement or ‘superfood’ that can ‘boost’ our immune system.
Your immune system is your body’s natural defence mechanism against pathogens (any living thing which can cause disease). The design of our immune system is complex and influenced by a balance of many factors, not just diet, and especially not by any one specific food or nutrient. It is essential to optimise several factors – including sleep, stress, exercise, as well as nutrition – to support its normal functioning.
Why focus on improving immunity?
- Prevention: Better immunity helps in preventing infections.
- Longevity: Stronger immune system can contribute to a longer, healthier life.
- Quality of Life: Fewer illnesses mean more time to enjoy life.
Lifestyle and immunity:
Lifestyle choices can either support or dampen the normal functioning of your immune system. If your immune system is working as expected, you’re less likely to get sick. When it’s dampened down for some reason – for example poor food choices or lack of sleep, you are more likely to get sick.
Let’s focus on food choices:
The best way to promote overall health is to follow a balanced and varied, healthy eating pattern. This means choosing foods from each of the food groups listed in the Australian Guide to Healthy Eating. Follow a dietary pattern that includes vegetables, fruits, lean proteins, starches (including wholegrains), milk and dairy products, and healthy fats. Dietary approaches that are limited in variety and higher in processed foods can negatively affect a healthy immune system. This means we can miss out on important vitamins that keep our immune systems working properly.
It is important to stay well hydrated, get plenty of vitamins – in particular vitamins A, C, and D, as well as protein and zinc. Don’t worry too much about these vitamins individually. If you include lots of colourful vegetables and 2 serves of fruit daily, you likely have bases covered, but here is a more detailed explanation below:
Protein:
Food sources: Meat, fish, poultry, yoghurt, milk, eggs, tofu, beans, wholegrains (particularly quinoa and buckwheat)
Benefits: Protein plays a vital role in all body functions but particularly in immunity, as it helps build and repair damaged immune cells.
Vitamin A:
Food Sources: Carrots, sweet potatoes, spinach, squash, pumpkin
Benefits: Vitamin A is crucial for supporting skin health, which acts as the body’s first line of defence.
Vitamin C
Food Sources: Oranges, berries, broccoli and bell peppers
Benefits: Vitamin C is an antioxidant, as well as being very important in supporting wound healing. Vitamin C also helps you absorb iron from your food.
Fun Fact: Although a vitamin C supplement is often promoted as a remedy for the common cold, research shows that for most people vitamin C supplements do not reduce the risk of catching a cold. However, research is emerging which shows it may help you recover from a cold slightly faster and have slightly milder symptoms.
Vitamin D
Food Sources: Oily fish, eggs and some mushrooms.
It is difficult to get sufficient vitamin D from food sources alone. The best way is via sunlight, through UV radiation, however this can prove difficult in Victoria in the colder months. Speak with your health professional about if you would benefit from a Vitamin D supplement in the darker months. Read more about Vitamin D here.
Benefits: Vitamin D deficiency (too low levels of vitamin D in the blood) is associated with significantly higher levels of inflammation in the body.
Zinc
Food Sources: Oysters, beef, pumpkin seeds, cheese, chickpeas, cashews
Benefits: Zinc is essential for immune cell function and messaging that occurs between cells.
Fun Fact: Some studies have shown that zinc lozenges and syrup speed up the recovery from the common cold if you start taking them when you notice you have one.
Other lifestyle considerations:
Aside from eating a nutritious diet– don’t forget about other important factors.
- Adequate sleep: Aim for 7-9 hours of quality sleep each night. Lack of sleep can lead to increased risk of illness.
- Stress management: Stress hormones like cortisol can reduce immune function. Techniques like meditation and regular exercise can help manage stress.
- Keeping active is important as exercise increases blood flow, and this helps to move our immune cells to more locations around the body.
- Reducing alcohol intake and not smoking are also very important aspects of supporting your immune system.
In Summary:
Remember, when it comes to avoiding winter viruses, the best line of defence is to avoid spreading and catching them in the first place – by staying home if you’re ill, regular handwashing, wearing a mask if you are vulnerable and keeping to well-ventilated spaces.
From a nutrition and lifestyle perspective, focus on choosing foods from each of the five core food groups, lots of veggies with our main meals, keeping active and reducing stress (where possible!).
For winter meal ideas rich in vitamins and minerals discussed, see our previous article on comfort food.
For individual nutrition advice, book an appointment with an APD at the Diabetes Victoria Clinic.
Carisa Sheridan
dietitian at Diabetes Victoria
Carisa joined Diabetes Victoria in 2023 and is originally from Ireland. She has worked in diabetes in Dublin, Ireland and in the Middle East before making the move to Melbourne. Carisa facilitates programs for people with diabetes both in-person and online.
Carisa loves spending her free time by the sea, at a book club or exploring one of the delicious coffeeshops Melbourne has to offer.
