Yet our faith that science will develop a pill or procedure to cure whatever ails us is unshakable. Since the Human Genome Project began spilling the secrets of DNA a decade ago, many of our hopes have been tied to the potential discovery of particular genes linked to specific disorders that, once decoded, will offer road maps for doctors and drug researchers to follow. But the potential of gene therapy as a cure for cancer remains limited. One comprehensive review of cancer-prevention research estimated that only five to 10 percent of cancers resulted from inherited gene defects. The same study found that 30 to 35 percent of cancer deaths are "linked to diet," with an additional 10 to 20 percent linked to obesity. Prostate cancers had a 75 percent dietary cause.
"We know that cancer is a preventable disease that requires changing lifestyle," says Bharat Aggarwal, a professor of experimental therapeutics at the M.D. Anderson Cancer Center in Houston. "No matter which cancer you pick, they've found out at least 200 to 500 genes have gone wrong. That means 200 to 500 pathways. The drug industry knows how to target only one pathway at a time. Natural products hit multiple pathways, so they slow down the progression of the disease."
Fuhrman is flabbergasted at the amount of money going into cancer-cure research. "We're not going to find a magic cure for cancer," he says. "We've got to prevent it."
Micronutrients, in his opinion, are "the fuel that turns on our body's anticancer defenses." Animal protein, on the other hand, raises levels of IGF-1, a hormone that stimulates growth in children but promotes tumor development in adults. Dr. Luigi Fontana, who conducted a multiyear study on long-term calorie restriction, observed a correlation between protein consumption and IGF-1 levels. "There's a perception that you can eat as much protein as you want," Fontana says, "and it's safe and healthy. Our data suggests that probably this is not correct."
With each book, Fuhrman has pushed the possibilities of nutritarianism a little further. A banner running across the bottom of 'Super Immunity's' cover promises, in capital letters: no shots – no drugs – no sick days. Fuhrman writes that "healthy people eating healthy food should never need to take an antibiotic." In his office, he dials that claim back a little, saying that antibiotics might be necessary on "very rare occasions." I ask for examples.
"Certainly, you could step on a sea urchin," he says. "You could get bitten by a cat."
Viruses, Fuhrman says, are relatively harmless in a healthy person; a bug that kills one person might not even cause symptoms in a committed nutritarian. Because Americans are hooked on immunity-depressing "fast food and sugar and junk," we aren't prepared for the kind of viral pandemic such as the 1918 Spanish flu, which killed at least 50 million people worldwide. "Some sort of swine flu/bird flu hybrid could kill 20 percent of our population," Fuhrman says. As for the annual flu shot, "it isn't effective at all – it doesn't work!" He's also skeptical about the number of vaccines the average American child receives. "There's no chance of anyone getting polio in this country," he says.