Your immune system is a complex series of cells and proteins that become activated in response to bacteria and viruses. The immune system then attacks these foreign invaders in an effort to keep you healthy. In this article, we will challenge some of the misconceptions about how the immune system works, and describe some ways to keep your immune functioning well.
We should first note what the immune system is not. This is important because fear about a lackluster immune system is being exploited in the current COVID-19 pandemic to sell many health products including diets, supplements, and exercises that are thought to have ‘immune-boosting’ properties.
A recent commentary at Science Based Medicine highlighted that: If you google the phrase “boost the immune system” you will find over 288,000 pages that give advice on how to give the immune system a lift. Curiously, an online search for published scientific articles yields only 1,100 references, most concerning vaccination. None of the references indicate that it’s possible to take a normal person and make their immune system work better than its baseline in order to prevent or treat infection.
So, while there is no shortcut to a stronger immune system, the good news is that there are many cheap and easy ways to prevent your baseline immunity from becoming compromised, to keep your immune system working optimally, and to contribute to improved function in the long-term. The only known strategies for achieving this include:
- Sleep: Get at least 7 – 8 hours of sleep, per night. Focus on good sleep hygiene like turning-off electrical devices at least 1-hour before bed, bathing just before going to bed, avoiding daytime napping, and avoiding exercise and food late into the night.
- Exercise: Exercise regularly, and strive to meet the WHO guidelines for physical activity. This comprises at least 150 minutes of moderate-intensity physical activity, per week.
- Stop smoking.
- Healthy diet: Eat a healthy, balanced diet. This is difficult to achieve because of conflicting information relating to what a ‘healthy, balanced diet’ might be. So, let’s explore this a little further.
What is a healthy diet?
Fruit and vegetables. In the US, only 1-in-10 adults eat the recommended amount of fruit and vegetables. These contain important micronutrients that contribute to a healthy body. Someone who is deficient in certain nutrients, e.g., vitamin D, may experience a decrease in immune strength. This doesn’t mean that supplementation is necessary, it just means that deficiencies can be avoided by consuming a diet rich in a range of healthy foods. A study from University College London found that there is a dose-response between fruit and vegetable intake and reduced risk of cardiovascular disease. Therefore, although a minimum intake of 5 different portions of fruit/vegetables per day is recommended, more is better.
Protein Intake. Protein aids in the growth and maintenance of muscle tissue. But protein also contains important amino acids that, if excluded from the diet, can lead to an impaired immune function. Strive to have a mixture of good quality protein in your diet and endeavor to eat some form of protein at most meals. This may come from meat and fish, poultry, eggs, and/or a little dairy. You can also obtain protein and important amino acids from plant-based foods including legumes (e.g. beans, peas, lentils), nuts, seeds, and whole grains. The general guidelines are to consume around 0.5 g of protein for every pound of body weight, per day. So, a 150 lb adult should target 75 g of protein per day, spread in even doses across meals.
Saturated Fat. Conventional wisdom suggests that we should avoid high intakes of saturated fat because of its association with cholesterol in the blood. Research from Imperial College London supports this and shows that high levels of saturated fat in the blood can increase inflammation and tissue damage. It is important, therefore, to limit your intake of saturated fat. In practice, this can be achieved by decreasing your intake of fried food (try broiling or baking instead), eating fewer takeout meals, and eating less confectionary (e.g., cakes, cookies, and pastries).
Alcohol intake. Alcohol disrupts immune system function in a number of complex ways. Moreover, excessive consumption is linked to an increased likelihood of acute respiratory stress syndromes (ARDS), sepsis, alcoholic liver disease (ALD), and certain cancers. According to guidance from the CDC, alcohol intake should be as low as possible, and we should limit ourselves to a maximum of one drink per day. Binge-drinking (consuming more than 3 drinks in an evening) should also be avoided.
In summary, making sensible lifestyle choices and following a healthy diet will help to keep your immune system in its best working order.
Nicholas Tiller, PhD and Asghar Abbasi, PhD
The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center