To see how lung microbes might influence disease susceptibility, researchers studied mice, which also start with sterile lungs that soon host microbes.
And, suppression of the immune system with increased susceptibility to colds, sleep issues, GI issues, fertility issues, memory problems, and even cancer.
And stress reactions can reduce the disease-fighting effectiveness of the body's immune system, thereby increasing susceptibility to illnesses, ranging from colds to cancer.
Athletes and leaner individuals, though, should aim for more, due to their lower proportions of stored of fat and higher susceptibility to muscle loss when losing weight.