When I started my practice in the 1950s, I couldn’t even suggest, as I do today, that I could help patients suffering with cancer overcome it through diet—even though it’s largely a food-associated disease. Today, there is a different climate in terms of health care in America. However, the American health system is deeply troubled. Chronic diseases such as heart disease, cancer, diabetes, and obesity account for more than 70 percent of U.S. health-care costs, according to the Centers for Disease Control and Prevention (CDC). Yet those who suffer from these diseases receive only about 50 percent of the recommended preventive care. One out of every four deaths in the United States is due to cancer. Over 65 percent of Americans are overweight; and the CDC estimates that obesity causes more than 112,000 deaths a year and is at the root of other conditions including diabetes, hypertension, arthritis, respiratory problems, depression, and gynecological complications, including infertility.

Yet I believe—I know—that cancer and these chronic conditions are preventable, and if these diseases were prevented or treated using my research and work in blood types, we could save well over $100 billion a year in health-care spending.

Today the powerful pharmaceutical companies still manage to get their drugs to the marketplace—many that have long lists of serious side effects or have not been tested long enough and are harmful to the body. (For example, Vioxx, a medication for arthritis, led to approximately 30,000 cardiac deaths before it was pulled from the market in 2004.)

Fortunately, there’s also a greater awareness of the role food plays in healing.

When I moved to Portsmouth, New Hampshire, 10 years ago, after practicing in my institutes in Brooklyn and Toronto and an office in Montreal for 40 years, I sought to wind down my practice and devote more time to teaching my work on blood types to other naturopaths. And yet the patients kept coming to see me: patients from as far away as California, Hong Kong, the Philippines, Mexico, and South America; patients from countries with socialized medicine, like England and France; and even patients who had health insurance and could afford expensive conventional medical treatments (few of my treatments are covered by insurance). Why would they do this? Why would they spend thousands of dollars and travel halfway around the world for the individualized programs that I created for them? Because what my father told me as a boy is true: good health is a person’s greatest treasure, and there’s not much you can do without it.

I’m gratified to see the growing awareness people have about the importance of foods, herbs, and exercise with respect to their health. Many medical doctors still label alternative approaches to healing—even mine—as “quackery” because proof of their effectiveness and the way the techniques work haven’t been scientifically verified, although the results can certainly be observed. Yet they nevertheless have had to start incorporating natural remedies into their practice because millions of Americans are using them and enjoying their benefits.

Yet this heightened awareness is only one step in the prevention and treatment of chronic disease. My clarion call after practicing for 50 years and treating over 50,000 patients is the same: all people are unique individuals, created by the shared genetics of two parents; molded by their culture, society, and geographic region in which they were raised and live; and directed by their dominant thoughts.

Most important, a person’s blood type—whether it is O, A, B, or AB—is nature’s most reliable guide in determining their individualized dietary needs.