Our immune system is an incredible and complicated system of biological functions that is on constant guard against environmental and internal stressors in order to keep our tissue cells healthy. There are two main portals into our bodies that make us susceptible to foreign invaders: the lungs and the stomach. So breathing and eating are the two life-sustaining activities that expose us to trouble; keeping our immune system healthy and strong is vital. As we age, many of our biological systems, including immunity, start to slow down and become less reliable. Therefore, adopting good lifestyle habits now will help to safeguard us for life.
Having a strong immune system can also mean we get less colds, coughs and viral infections during the year, and when we do fall victim to them, we fight them off quicker. It can also reduce our odds of developing more serious conditions like cancer and heart disease. The more we learn about the immune system and our lifestyle habits, the more we learn about their links with chronic diseases. There are three main lifestyle changes we can all make that will help shore up our immune system.
Getting the right amount of exercise
Regular physical activity is associated with a better immune system; although the exact reasons are unknown, there are several theories that suggest that moderate physical activity could:
- Help the expulsion of bacteria from the lungs and airways system, which reduces the odds of getting colds and flus.
- Allow for better circulation of immune fighters such as antibodies and white blood cells, giving them an advantage for tracking down disease-causing invaders more quickly.
- Cause core body temperature to rise, to prevent bacteria from thriving.
- Help relieve stress, which enhances “pro-inflammatory” hormones.
Whilst it is true that these effects of exercise are transient, over time, regular exercise appears to improve the function of the immune system. However, more strenuous activity such as very long distance running or “over-training” could do the opposite, as it puts more stress on the body – so moderate activity is better.
Getting the right amount and type of relaxation
Stress comes in many flavours; it can be an emotional state caused by frustration, panic or worry, anxieties and fears among others. But stress can also be physical such as over-exercising, exposure to cigarette smoke, drinking too much alcohol or even spending hours each day in a sedentary occupation. All types of stress impact upon our immune function. Emotional stress increases certain hormones in the body known as “stress hormones”, and over time, a stressful lifestyle can cause deregulation of these hormones which impedes our sleep, affects our blood pressure, and impacts upon immune function. Cortisol (a stress hormone) production can also be affected by poor sleep patterns, such as those found in shift-workers or those who sleep too little or too much.
The antidote to all of this is to moderate our lifestyles and find something that brings us mental calmness. Regular exercise, yoga or tai chi, spending quality time with the family all contribute to mental calmness.
Getting the right nutrition
Nutrition has a huge influence upon our immune system, both directly and indirectly. It affects us directly through the digestion and absorption of nutrients in our foods, it affects us indirectly via the billions of bacteria that reside in our gut.
First rule of immune health: eat more plants! A Mediterranean-style, plant-based diet will undoubtedly give you a better head start than a northern European style diet that is meat and dairy based.
Plants (fruit, vegetables, nuts and legumes) provide the following that a heavy animal-based diet cannot:
Sometimes referred to as roughage, dietary fibre belongs to the carbohydrate family that can only be sourced from plants. It is the part of the plant that cannot be digested, and therefore forms the bulk of our stools. A diet low in carbohydrate and therefore, in dietary fibre can be poor for both gut health and our immune system. The beneficial bacteria that reside in our gut produce fatty acids that have both an anti-inflammatory effect and are key to promoting the efficiency of our immune cells. These same bacteria rely on a diet high in fibre to thrive in the gut, and a gut with good populations of helpful bacteria also keeps the disease-causing bacteria at bay.
Vitamins and minerals
Another good reason to eat a diet high in plant foods is because they are the only source of vitamin C, a powerful anti-oxidant. Vitamin C is one of the most popular vitamin supplement consumed today, particularly during the winter season. Vitamin C is water soluble and therefore is not stored in the body, and so we need exposure to it right throughout the day. Taking one tablet per day allows only one point of exposure, and what isn’t required at that point in time is excreted in the urine. It is recommended we eat vitamin C rich foods, where the vitamin is locked inside the plant cells and is released during digestion, so less of it is lost. Furthermore, the way vitamin C is provided in nature is safer for us, diabetics and people with kidney disease should avoid vitamin C supplementation unless medically supervised – similarly those on regular medication should never take supplements without medical advice first. A diet varied in fruit and vegetables gives us most of the vitamins we need, and if you steam your vegetables rather than boil, you will preserve more of the vitamin C within it.
Plant foods also contain chemicals known as phytonutrients, which are substances that give plants their colour and flavour. Phytonutrients have many immune-supporting properties such as providing us with vitamin A, another antioxidant that mops up free radicals inside of the body.
Although not a true vitamin, vitamin D has recently been connected with the regulation of the immune system. This aspect is to be further studied, but there is no doubt about the importance and significance of vitamin D and health. It is now widely believed that northern countries such as the UK (and particularly Scotland) are prone to deficiencies in vitamin D during the winter months, as we’re not able to adequately produce it from the sun during the period October to March. Consuming more fish, eggs and dairy would alleviate this to some degree, but some of us may have to supplement during these months. One tip, try leaving mushrooms in direct sunlight for about an hour, they naturally produce vitamin D!
Essential fatty acids
Nuts, seeds, olive oil, avocados are all good sources of vitamin E (an antioxidant vitamin) and “monounsaturated fats”, which have long known to help modulate the immune system. Fish is a great source of essential fatty acids found in “polyunsaturated fats” which are natural anti-inflammatory agents and provide the best source of omega-3 fats. Eating oily fish twice a week is a great way of increasing our omega-3 intake, and using nuts and seeds to snack on rather than crisps and cereal bars are a good way to increase all “good fats” into our diets.
Not only are the nutrients in our food important, but the way we cook and prepare food can affect our immune system too.
Firstly, it’s wise to reduce our meat consumption, and have at least one day a week that is vegetarian. Try and switch to fish, white meat and poultry and then consume red meat and processed meats more for occasions rather than regular consumption. Don’t burn or char meat if you can avoid it, and if you enjoy a barbeque, consider marinating the meat in beer first! It reduces the harmful effects of PAHs that are created when meat is charred.
Vegetables are best steamed, stir fried quickly or microwaved until just cooked. This will help preserve the nutrients inside them. Any water that is used to cook vegetables should be preserved and incorporated into making stocks, sauces or gravies. Eating vegetables slightly “al dente” or with a bite to them will help avoid over-cooking and will also preserve their flavour too. Wash vegetables well and think about cooking them in their skins; most vegetable and fruit skins are edible and often particularly high in fibre.
Buy vegetables in their natural state and not pre-prepared (such as peeled and diced and ready to cook). Nutrients in food degrade quickly after being picked and stored and then if they’re prepared in a factory and sitting in a supermarket for a while, this speeds up the degradation process even faster.
If you like seeds in your porridge or breakfast cereal, think about smashing them up in a pestle and mortar. Tiny seeds like flax and chia seeds are often missed in our chewing action, and their shells cannot be broken down by our digestive enzymes so the wonders inside them end up in the toilet. You can buy flax and chia already milled, but it’s best to do it yourself if you have time. If you toast your own seeds, take care with how long you toast them as a high heat and long cooking hours denatures the natural beneficial properties of nuts and seeds.
Seb is a writer and blogger of food and nutrition. He holds a bachelors and a masters degree in nutrition science, and has studied sports and exercise nutrition at postgraduate level. He specialises in plant-based nutrition and believes passionately that we can all live with a little less meat. He writes for www.veggieandspice.com and www.itsaboutnutrition.com