Vitamin D and Calcium Protect Against Some Cancers Drs. Cedric F. Garland and Frank C. Garland of the University Of California School Of Medicine at San Diego published a book entitled The Calcium Connection. This book deals with their studies of the relationship between vitamin D and calcium and preventing breast and colon cancers. They were attending a lecture at Johns Hopkins University that included maps showing the incidence of each of the major cancers for each of the 3,056 counties in the U.S. These maps were prepared by Dr. T. J. Mason and his colleagues at the National Cancer Institute from data supplied by the National Center for Health Statistics. I published some of these maps in the first edition of Cancer and Its Nutritional Therapies, and they are repeated here for your convenience. Note, by looking at the fifth and last map, "Melanoma," that it is obvious that people living in warmer climates have more exposure to the sun and thus more overexposure to ultraviolet energy; thus, people living in warmer climates have more skin cancer. Now look at the third figure, "Breast cancer, and white females." Do you see a pattern? Dr. Cedrick Garland did. He noticed that it looked as if someone had drawn a heavy line along the 40th parallel—through the middle of California, and the tops of Arizona, New Mexico, Texas, Tennessee and the Carolinas. The vast majority of the high breast cancer areas are North of this line while most of the low breast cancer areas are South of it. The same is true of the map for colon (large intestine) cancer. For both cancers, there is a correlation showing a decreasing gradient of mortality rates from North to South. "At first we thought that the link was due to differences in the diet between the North and South, but when we look at data from the Department of Agriculture, we found that (no dietary pattern) fitted the map we had produced for cancer."' The next obvious explanation would be exposure to sunlight. The more sunlight reaching the skin, the more vitamin D that the body forms in the skin from cholesterol-derived compounds. So the scientists decided to look at the possible role of vitamin D. Where there were some apparent exceptions to the map pattern in large cities in the South, these can also be explained by the sunlight theory. People living in large cities live in polluted air that blocks sunlight and live in the shadows of tall buildings. Also, city folk tend not to wear short-sleeve shirts and shorts as often as country folk, and they tend not to be outside in the sunniest hours. The Drs. Garland published their hypothesis in 1980. In 1984, the Drs. Garland convinced some of the researchers, who looked into the effects of vitamin A and beta-carotene on lung cancer, to use their data bank and blood samples to look into calcium and/or vitamin D and colon cancer. The researchers, originally led by Drs. Richard Shekelle and Jeremiah Stamler, conducted the Western Electric Study wherein 1,954 men living near Chicago volunteered to be studied over 20 years. The researchers found that the risk of colon cancer was inversely correlated with dietary vitamin D and calcium. When the combined intakes of vitamin D and calcium were ranked, and then grouped as "fourths" or "quartiles" from lowest to highest intakes, the observed risks were 38.9, 24.5, 22.5 and 14.3 per 1,000 populations. This association remained significant after adjustment for age, cigarette smoking, body mass index, alcohol consumption, and percentage of calories obtained from fat. The study found that a dietary intake of vitamin D greater than 3.75 micrograms of vitamin D per day was associated with a 50 percent reduction in the incidence of colorectal cancer, and that a dietary intake of 1200 milligrams or more per day of calcium was associated with a 75 percent reduction. The Drs. Garland and their colleagues continued to look into this possible relationship. Later they reported that "people who get at least 400 IUs of vitamin D daily are half as likely to get colon cancer as those who get less." Dr. Garland also suggested that "breast cancer rates could be significantly cut by a diet rich in vitamin D."4 In 1989, Dr. Garland explained, "It appears that cancer is prevented because you need vitamin D to absorb calcium, and calcium inhibits cells from proliferating and becoming cancerous. . . . We're confident that increasing dietary vitamin D will reduce the overall incidence of breast and colon cancer."' In 1990, Dr. Garland added, "Recent European studies of the metabolic roles of vitamin D indicate that when an adequate amount of vitamin D is present, the cells bind together tightly. Cells that are tightly bound together grow in a much regulated way. Individual cells are then less able to run out of control. When vitamin D is lacking, the binding loosens, leaving the cancer-prone cells to grow uncontrolled. The result is often cancer."' An eight-year study of 25,802 Maryland residents found that people with blood levels of vitamin D that correlate to 400 IU or more daily of vitamin D had half the risk of colon cancer of those with lower amounts of vitamin D in their blood. The cancer rate was three times higher for those who had less than the amount of vitamin D in the blood equivalent to an intake of 270 IU daily. The researchers examined the breast cancer and colon cancer rates in 29 U.S. cities and 20 Canadian cities and found that the greater the amount of sunlight-blocking air pollution, the higher the breast cancer and colon cancer rates. Dr. Garland's research group also reported a threefold increase in the incidence of breast cancer in the republics of what was formerly called the Soviet Union, where there are low sunshine levels.' We will again discuss the roles of vitamin D and calcium in Chapters 19 and 20 on Breast Cancer and Colon Cancer respectively. Researchers can find a good review of vitamin D and mechanisms for cancer prevention in reference 7. Calcium We don't really know if it is the vitamin D, the calcium, or both vitamin D and calcium working together that is protective. Since the major protective factor could be calcium, let's look at some of the supporting evidence. Dr. Cedrick Garland presented his evidence to Drs. Martin Lipkin and Harold Newmark at the Memorial Sloan-Kettering Cancer Center in New York City. Drs. Lipkin and Newmark were studying persons at high risk for colon cancer due to their family histories of high incidences of colon cancer. Drs. Lipkin and Newmark found that these high-risk persons, before taking calcium supplements, had an unusually high rate of cell proliferation (cell division) in their colons. After taking 1250 milligrams of calcium carbonate daily for two to three months, the rate of cell division returned to normal.' Drs. Lipkin and Newmark now conclude that "calcium contributes to the progression of epithelial cells through all phases of the proliferative cycle and into stages of cell differentiation; intercellular concentrations of calcium that are required for cell renewal, however, are lower than those required for epithelial-cell differentiation. These effects of calcium are modulated by interactions with vitamin D, phosphate, and fats, all of which are dependent on dietary intake. Thus, low calcium intakes cause epithelial cells to proliferate but not differentiate (mature) to become normal cells. Fat increases this proliferation, but it can be overcome with adequate calcium intake. "Increased dietary calcium inhibits hyper proliferation of colon epithelial cells induced by increased levels of fats or bile acids in the colon. When carcinogens induce hyper proliferation of colon epithelial cells, the hyper proliferation is decreased by adding dietary calcium."' We will look into the practicalities of this relationship again in the chapters on breast cancer and lung cancer. The 1989 adult RDA for vitamin D is 200 IU per day. Dr. Garland suggests that 400 IU is both safe and protective. Problems from too much vitamin D don't appear until 1,000 IU or more daily. The adult 1989 RDA for calcium is 800 milligrams per day. You may wish to take a supplement containing 800 milligrams of calcium (elemental) in addition to the calcium in your normal diet. Other Protective Food Factors So far we have examined several vitamins and minerals for their proven individual roles in protection against cancer. There is no mistake that these individual nutrients are protective. This has been proved by laboratory animal studies where the only variable was that particular pure nutrient, and has been confirmed by epidemiological studies. However, there is more. Foods contain many hundreds of compounds, and many compounds also have protective roles against cancer. It is important to take advantage of all these compounds by making sure that you eat plenty of fruits and vegetables. It is then wise to increase your protection by taking additional amounts of the proven protective nutrients. I emphasize this dual approach for two reasons. First and most important, it is the only approach that gives optimal protection. Secondly, this approach balances the statements by some scientists who still believe that it hasn't been proven that the individual nutrients are protective—they keep holding out that there may be some other factor(s) in fruits and vegetables that provides the protection. Unfortunately, these scientists are aware only of the epidemiological studies that indicate fruits and vegetables are protective, and they have a strong but unfounded prejudice against food supplements. These scientists do not seem to be aware of the studies on laboratory animals that prove that individual nutrients are protective. However, they do have a point that there are indeed other compounds that are also protective and we should get ample fruits and vegetables in our diets. Fruits and Vegetables A moderate increase in the amount of fruits and vegetables consumed by the "average" person even provides significant protection against tobacco- and alcohol related cancers such as cancers of the mouth, throat and esophagus. The point is that it doesn't take that much of an effort to reduce your risk of cancer from evens the most potent carcinogens. When the cancer rates for those who eat the recommended amounts are compared to those who eat few fruits and vegetables, typically we see a reduction in risk by one- half; and for some cancers, a 70 percent reduction.' Unfortunately, too few of us eat the recommended five or more servings a day. Several surveys indicate that only about 23 to 25 percent of us do eat the recommended five servings. On the average, we eat only about three-and-a-half servings per day. On any given day, only one in five Americans ate a fibrous or cruciferous vegetable and only 28 percent ate a fruit or vegetable rich in vitamin C. When Dr. Gladys Block was at the National Cancer Institute, she led a longs-term dietary study of about 11,000 persons. She found that 40 percent of Americans do not eat a single fruit on a typical day, and 20 percent don't eat a single vegetable.3 Also, half of us don't eat vegetables other than potatoes and salads.