If you take in all high-quality foods, and still also take in high levels of refined carbohydrates, (what many people are doing, especially when they are fasting) you will not get the full benefit of increased immunity. The high level of refined carbohydrates in your diet is almost certain to lead to high levels of glucose in your blood, which in turn will cause you to release large amounts of insulin – and high levels of insulin can severely depress your immune system. By keeping your blood sugar and insulin levels as low as possible, you keep your immune system at a high level of readiness.

Sugar in itself also has a severely depressing effect on your immune system. Eating sweet foods of any sort interferes with the ability of your white blood cells to attack and destroy invading pathogens. The negative effect of just one glass of soda-pop or even soft drink can linger for more than twelve hours. In addition, sugar lowers your body’s ability to produce antibodies, the chemical messengers that recognize invaders and sound the alert that mobilizes your white blood cells to attack them.

Another crucial element of your diet as it relates to immunity is your intake of essential fatty acids. The balance of omega-3 and omega-6 fatty acids is very important for your production of the chemical messengers – hormones and eicosanoids – that tell your immune system what to do. If the balance is tipped too far in favor of the omega-6 EFAs, as it often is among people who eat a typical high refined carbohydrates diet, the pathways that create the chemical messengers will not function properly.

When your white blood cells (lymphocytes) fend off an invading pathogen, as they do quite literally millions of times a day in a healthy person, they generate large quantities of free radicals in the process. If you’re sick, your immune system will be generating a higher rate of free radicals. To protect yourself against the damage from the excess free radicals, you need a diet high in natural antioxidants, as well as supplementary vita-nutrients.

There is one final factor to consider in building your immunity. You have probably noticed that you are more likely to get sick when you’re under stress. That is explainable. Stress produces the hormone cortisol, and cortisol can slow your immune system or shut it down altogether by blocking your production of chemical messengers. Cortisol levels rise naturally as we get older. Combine that with the constant high stress of life at the start of the twenty-first century, and it’s quite likely that your cortisol level is continuously high, with a correspondingly depressing effect on your immunity.

Your body’s primary defense against invading pathogens is your skin and your epithelial cells – the linings of your organs, including your respiratory  and intestinal tract. If these are weak, harmful infectious agents can enter more easily. If an infectious agent does make it past your epithelial defenses, your internal defense systems – the various kinds of white blood cells, antibodies, and chemical messengers – take over. All aspects of your immune system are on constant patrol to detect not just invading pathogens but also defective and cancerous cells within your body. To maintain a strong defense, you need to pay attention to the following: