The #1 immune suppressant out there is...Stress.
But I'm not going to talk about the most common and well known types of stress. It goes beyond just work stress or financial stress or life stress. The stress in this discussion boils down to the following things: diet, chemical exposure (often connected to diet), exercise, sleep quality/quantity/timing and emotional history.
Each of these 5 elements can increase or decrease your stress levels, depending on how you use them, thereby strengthening or weakening your immune system, making it more or less likely that you get sick. (whew)
Let's start with diet. Foods that will add stress to the body are foods that disagree with you on a physical level--refined sugars, refined flour, fast food, drugs, excessive alcohol, caffeine and other stimulants, foods not grown on a farm but instead made in a laboratory, artificial sweeteners-- you get the picture? Foods that don't nourish the body will cause it stress that can eventually lead to heart disease, diabetes and some forms of cancer. These foods can be temporarily satisfying on an emotional level, but usually leave you feeling tired and bloated. Food that was grown on a farm and is eaten in that original form, i.e. whole foods, will nourish the body, supporting it in its daily endeavors, provided that you don't have an underlying allergy or sensitivity to them. Ideally food is organically grown, pasture raised and not treated with any sort of growth hormones, antibiotics or pesticides. The more chemical exposure you have through your food, the harder your body, especially the Liver and Kidneys, have to work to filter it out. Even prescription medication adds to your chemical and stress load to the body. I'm not saying to stop taking your medications, you need to speak to your prescribing doctor about that. I'm only saying that ingesting chemicals made in a lab will add to your overall stress load and you might want to seek alternative ways to manage your health problems.
Chemical exposure is not just limited to food. The air we breathe, the water we drink, the products we use on our skin and hair all add to our chemical load. Not to mention plastic containers that can leech chemicals into our food and water. Even BPA free containers contain Bisphenol S which isn't good either. The higher your overall chemical load, the more strain on the body, impairing its ability to function properly. Use glass containers for food and try to buy skin and hair products that contain ingredients that you would consider eating. Whatever goes onto your skin gets absorbed into your blood stream; if you wouldn't eat it, you probably shouldn't put it on your skin.
Exercise is an interesting subject. Everyone should exercise, 3-6 times per week ideally, but there is more to it than that. Exercise should energize you; if it doesn't, it is causing harm to your body. Ideally moderate exercise is best, including some form of strength training and cardiovascular workout. What you do isn't important as long as it is fun and you are inspired to continue for life. Some people need more intense exercise to burn off excess energy they have or to help them deal with their daily stresses. Others need milder exercise because they are systemically energy deficient. These latter people will often feel exhausted after more intense exercise and this will add stress to their bodies. These people need to focus on gentler exercise or maybe intense but for shorter periods of time. You need to adjust your exercise regimen to how you feel when you are done. It may take a little playing with but you want to find an type of exercise that you like and makes you feel good afterward. This will support your immune system.
Sleep is immensely important to health, not just quality and quantity, which are more obvious, but when you sleep is important too. Studies have shown that people who work the graveyard shift have shortened lifespans because they are working against normal circadian rhythms. Being awake when it is dark and asleep when it is light is unnatural and works against the body's production of melatonin (the sleep chemical in the brain) which is only produced when there is no light. Ideally you want to be asleep before 11pm and then sleep between 7-9 hours (more for kids and teens); ideally you should wake up without an alarm clock feeling refreshed and ready to take on the day. Sleep deprivation can lead to weight gain, poor mood and lower coping skills. The increase stress on the body from lack of sleep can also lead to heart disease, higher susceptibility to colds and flu and slower healing. Sleep is when the body heals and restores itself; if you are not allowing that to happen sufficiently, it can cause damage to build up over time.
Lastly emotional history can play a part in stress to your body and mind. Holding grudges, history of trauma or abuse, constant worry, inability to let go of grief, these can all be stored in the body and affect your health. Anger, frustration, fear, worry, grief, sadness and joy are all normal natural emotions to have. However when they are not processed and released, they can actually harm the body. How these work is a bigger discussion for another time, but let's just say that if you don't deal with your "stuff" your body sends you louder and louder signals until you do. Holding onto what is unnecessary or what no longer serves you will hamper your immune system by causing undo stress.
Stress management alone can help cure most modern diseases, like heart disease, diabetes, high blood pressure and cholesterol. Stress leads to inflammation which is really the underlying cause of all of those diseases. The more you can do to help yourself feel better, the longer and healthier your life will be.
Over the next few months I will be going into more depth on each of these topics. Feel free to leave comments here or email me at firstname.lastname@example.org about any specific questions that you would like answered and I'll do my best to answer them.