Medically reviewed by Dr. Shunmukha Priya, Ph.D. in Food Science and Nutrition
Immunity, of late, has become a buzzword. This is majorly because of the Covid-19 pandemic that has raged the world. The fact that the mortality rate is significantly higher among the people who have comorbidity or have weak immunity is making many of us wake up to the importance of a healthy immune system.
Unfortunately, it took a pandemic for many of us to realize the importance of the immune system. But its importance is way beyond Covid 19 or coronavirus.
Functioning of your body’s immune system is essential for your body to fight off foreign particles like bacterias, viruses, allergens etc. Sooner you work upon it, better are your chances of warding off infections and diseases.
Immune system is not a single organ. Rather it is a combination of a lot of different things which often work in unison to protect your body against the invaders. There is no single magic pill which can make or break it. Nor is it completely invincible.
However, there are several steps you can follow and act upon, to make your immune system better.
Here are some do’s and don’ts if you are hoping to build a healthy immune system.
Do’s for a healthy immune system
1. Right diet
Eating right is the first step towards good health. Your food provides you with the vital nutrients you need for your day to day activities.
Many of us tend to focus only on macro-nutrients like carbohydrates, proteins and fats. Worse, many of us think of nothing but taste buds – with no thought given to nutrition.
While macro nutrients are important, it is also important to understand the importance of micro-nutrients like essential vitamins and minerals. These are usually found in fruits and vegetables.
Different fruits and vegetables provide different sets of nutrients. Hence it is important to incorporate a variety of fruits and vegetables in your diet. Some vitamins that help in boosting immunity are Vitamins A, C, B6, D, E. Likewise minerals like zinc, iron, selenium etc. can help boost immunity.
Some foods that can help boost a healthy immune system are spinach, oranges, nuts, bell peppers etc. In addition to these, anti-oxidants (found in berries, beans, spinach, green tea etc.) have also proven to have a positive effect on your immunity.
While these vitamins and minerals are important, it doesn’t mean that we should ignore other vitamins and minerals. Most of them perform key body functions, deficiency of which may make the body susceptible to different health issues. 
2. Exercise Regularly
You don’t need to be a marathoner or a sport expert to build good immunity. However you should be doing some exercise.
Choose something you like – be it running, swimming, cycling, yoga or pick up some sports. The idea is to do something, even if not too taxing (like a 30 minute walk!). Ideally, you should exercise for at least 30 minutes a day, 5 days a week.
While the link between exercise and production of immune cells is not clear, exercising does have an impact on your immunity.
Exercise is good for your overall health and well being. It helps maintain body weight, improves blood circulation, helps in regulating blood pressure etc. It also reduces your susceptibility to various lifestyle diseases.
These all factors help your body’s defense mechanism work better, when there is need. Good circulation can also help in transporting your cells which help in immunity transport more efficiently in your body. 
3. Sleep Well
Sleep is an important yet underrated part of your lifestyle, which has an effect on your overall well-being.
Research has shown that effectiveness of T cells, which is helpful in fighting pathogens, is related to getting good sleep.
During sleep, your immune system releases proteins called cytokines. Some of these cytokines help promote sleep.
When you have an infection or inflammation, these cytokines are helpful. Good sleep can enhance production of these cytokines, while a poor quality sleep may decrease their production.
4. Good personal hygiene habits
Did you know that a major part of increase in life expectancy over the last century or so can be attributed to rising awareness of personal hygiene and sanitation. (In addition to scientific advances that have taken place in the field of medicine)
Covid 19 epidemic has made washing hands a much more frequent affair than it used to be, probably for good.
- Habits like washing your hands regularly (after using washrooms, before and after eating, after coming home from outside etc).
- Covering your mouth and nose using handkerchief.
- Cleaning bruises and wounds etc are helpful in avoiding infections and preventing entry of germs in the body.
While these habits may not have a direct impact on your body’s ability to fight germs. They do have a positive impact on germs being denied access to your body. And many of the infectious diseases being contagious, these habits can collectively be useful in avoiding spread of the diseases. 
5. Home remedies and supplements
Some home remedies and supplements can really help your immune system function better. While they are not a substitute for the right diet, they can certainly complement it.
Several herbs like ginger, cinnamon, basil leaves, turmeric, cloves, black pepper etc. are beneficial for a healthy immune system.
Some of them are (or can be) added to daily food preparation (e.g. Basil leaves or tulasi or ginger in your tea, ginger in dal, a spoon of turmeric in milk etc). You can also make some concoction using them and take it as a supplement. 
Don’ts for a healthy immune system
1. Avoid Smoking
Smoking is associated with a lot of health issues. Researchers have time and again proven that smokers are usually less healthy than non smokers.
It worsens the effects of pathogens in the body, as well as compromises on your body’s response to the attacking pathogens.
Smoking reduces the protective antioxidants such as vitamin C, in the blood, as well as reduces the blood flow to different parts of the body. It increases the free radical in your body. This imbalance of the body may make you prone to some autoimmune issues.
2. Avoid Junk Food
We all know that junk food is bad for health. And so are foods loaded with sugar. However, they have an effect on things much more than weight. They can be instrumental in causing several lifestyle diseases.
In addition, the junk food you eat will often be at the cost of nutritious food you would have otherwise eaten. This can eventually make you deficient in nutrients that can be essential to your body, including functioning of your immune system.
3. Restrict Consumption of Alcohol
Research has shown that alcohol has an adverse affect on both innate as well as adaptive immunity. Regular alcohol consumption leads to predisposition to a wide range of health issues. Also, absorption of alcohol via your digestive tract alters the composition of gut microbes which affect the digestive system.
Excessive consumption of alcohol can reduce T Cells, C Cells and macrophages, all of which are important in fighting pathogens and smooth functioning of your immune system.
If you consume alcohol, you need to do it in moderation. Else your body may need to pay a high price for it. 
4. Avoid Stress
Stress may not be entirely unavoidable due to a variety of reasons, including several which are beyond your control.
Telling someone to “avoid stressful situations” is easier said than done, and not always pragmatic. However, one can choose to respond to stress and try to reduce stress wherever possible.
According to American Psychological Institute there is a high correlation between stress and diseases. If you are stressed, or depressed or experience loneliness, there is an increased likelihood of you falling sick.
Managing stress, especially long term stress, even if not too severe, can help people fight pathogens and infectious diseases better.
Practice of yoga, meditation can help you control your stress. At the same time, a good social circle and support systems can also be helpful. 
5. Avoid Being Lonely
This is an often overlooked factor. It has been seen that people with an active circle of family and friends usually have better response mechanisms to health issues, including infections.
Research has shown that being lonely can often lead people to perceive life as a lot more stressful (vis-a-vis when one has an active social circle). This in turn can lead to higher stress and weakened immune system.
So, do take out time to connect with your family and friends. Have an active social life. Pick up hobbies. Have things to look forward to even beyond work. It is not just good for a healthy immune system, but also your mental well being and overall health. 
Immunity is often correlated to age. The older you get, the worse your immune system tends to become. There is no denying that.
Yet, there are countless stories of people who have, to an extent, defied it. So there are stories of people who are living much healthier in their 50s and 60s than they did in their 30s and 40s.
This has been possible because of several lifestyle changes that they have undertaken to make their bodies better and healthier.
You cannot control your age. There are some aspects of your health you may never have control over. Nor have they been breached by frontiers of science.
However, there is a large aspect of your lifestyle which is under your control. You can take control of it and take steps in the right direction.
You don’t need to hit the gym everyday and pump iron to develop a healthy immune system (though it may be helpful!). All you need to do is make some good lifestyle choices.