A reader asked the above question about the cause of benign tumors. As in cancer, a benign tumor involves a proliferation of cells beyond normal limits, however, there is no invasion of surrounding tissues (although there is often pressure and crowding of surrounding tissues) and there is also no spreading by metastasis, in which cancer cells break off, circulate in the blood, and then get established elsewhere in the body. And that's what makes a benign tumor "benign." However, as for what causes them, I think it's best to look at benign vs. malignant as a continuous process. Sometimes, benign tumors do become malignant. For instance, uterine fibroid tumors, which are the most common benign tumor among women, become malignant in about .1% of cases. That isn't much, but that number would probably be higher if not for the fact that surgery is often performed on fibroids.

But, as far as actions to lower the risk of tumor formation, I would recommend the following:

1. Control your weight and your caloric intake. Tumors grow under conditions of nutritional excess. That's the fuel that makes them grow. Controlling calories and keeping oneself lean is the most important thing in tumor prevention.

2. Exercise regularly. Tumors grow under stagnant circulatory conditions. And the fact that the abdomen and pelvis are the most common locations for tumors is because that's where circulatory stasis most commonly occurs. When you exercise vigorously, you drain your abdomen and pelvis of blood- temporarily- and that is a very good thing.

3. Stop all poison habits. Smoking tobacco is the leading cause of tumor formation, and drinking alcohol is high on the list as well.

4. Eat lots of fresh produce. Fruits and vegetables contain a myriad of substances called "phytochemicals" which inhibit abnormal cell growth. There are thousands of different phytochemicals. So eat a wide variety of fresh plant foods every day and include a substantial amount of raw produce. Everyone should eat at least one large raw green salad every day.

5. Take Vitamin D3. There are many supplements which may confer protection against tumors, but if I were going to recommend only one for that purpose, it would be Vitamin D3. This time of year, auturmn, I am taking 5000 IUs of Vitamin D3 daily. During the summer I take only 2000 because of all the abundant sunshine. But the rest of the year, I go up to 5000 IUs every day. Vitamin D has a specific effect to signal cellular "apoptosis" when needed, which is where abnormal cells implode, or you might say commit suicide. Realize that any of us may have already had cancer but we just don't know it because the process was stopped before it got out of hand. Vitamin D plays a cardinal role as a watchdog in this process. Overall tumor rates are lower at the equator than anywhere else in the world because of all the sun. And unless you live at the equator or close to it, you probably need to take Vitamin D for a good part of the year.