There is now a growing body of literature in the area of diet and obesity. Several of these studies have used animal models to show that an elevated blood sugar level in the body is in itself a trigger for the immune system. In humans, these animal studies have also been consistent with the results of human studies. However, it is important to keep in mind that the results from some of these animal studies, especially the ones showing that dietary carbohydrate has an effect on body weight, may have been more due to effects of the animals' genetics rather than the fact that there was an effect on the diet. In humans, one of the most well-known and well-designed studies using human intervention studies to examine the effects of a low-fat diet on weight was the Leibel study of 1986, which used a group of 40 women to eat ad libitum a diet that provided a high fat and a low carbohydrate diet for 7 to 14 days and measured weight change and blood lipid levels using a semi-quantitative glucose meter. The women were also given either a low-fat vegan diet or a moderate carbohydrate diet.
There was a trend for weight loss in the moderate carbohydrate group, but no effect was shown when the subjects were on a moderate fat diet. A number of studies using animal models to investigate the effects of dietary intervention on disease have been done with very different models including rats. In some models, there was a clear effect of dietary fat, whereas in others there was no effect at all. In some of these models, there was even no effect at all on the immune system response. As a result, the person doesn't get sick or have a dangerous immune response to the pathogens the body is already exposed to, and this is what is so amazing in the research we are seeing today. We are seeing, to a large extent, the natural history of the body as a complex adaptive system.
We are discovering how the body learns to recognize foreign proteins and to defend against them. This conjugated estrogens that the system has the ability to adapt rapidly, to learn from its experience and to respond rapidly to new situations in order to defend itself. The human immune system is incredibly complex, and yet the immune system works so well that it keeps us healthy.
I've written quite a few articles on this, but in short, the immune system is conjugated estrogens of specialized cells in the skin and lymphatic vessels that are specialized to fight foreign bacteria and viral pathogens. The cells do this by releasing molecules called cytokines that are proteins, like those that fight disease, that activate a particular immune response that leads to tissue damage and inflammation. This damage is usually temporary, because the cells don't know what to do with the inflammation they create. As the cells are learning, and reacting, to the foreign invaders, they eventually find the right molecules to recognize as foreign, which leads to the formation of a new cell, which then produces the cytokine molecules to signal that the cell is no longer a foreign cell, and to tell the next cell. The body has created the mechanism for the human body to respond rapidly, and with extraordinary effectiveness; the only problem is that it hasn't done it in a sustainable way for a long enough time to get rid of all the foreign invaders. We are still in the research phase of our understanding of how the immune system works, and we don't really have much data to base our conclusions on. We don't know if these immune responses are going to be strong enough in the future to keep the immune system functioning and safe. We don't know how the immune system will react to future invaders; there is a chance that it has the ability to recognize a new foreign protein that causes an immune response, but what happens in the next few days or weeks is not very clear.
So let's see how our knowledge of the immune system works for some of our common bacterial or viral infections. Bacteriophages are small, parasitic, non-pathogenic cells made of DNA and phospholipids that are part of our immune system's defenses against microbes. They are used by the immune system to recognize foreign DNA or proteins. In fact, the immune system has a number of bacteria that can be attacked by a phage, such as Streptococcus pyogenes and Haemophilus influenzae. There are actually thousands of different phages, and they all can be used to target a single bacteria, and so the immune system is able to fight a wide variety of bacteria in the body.