Back in the ’90s, scientists for two major cancer-research organizations reviewed thousands of studies and saw armies of broccoli, cabbage, Brussels sprouts, onions, tomatoes, garlic, carrots, and citrus fruits turning the tide on various cancers. Then, just a decade later, the same scientists said the evidence had since become “somewhat less impressive.”
It was a classic case of science coming off as, well, fickle. One minute, chocolate and beer are good for you. The next minute, science says “sorry” and snatches them from your hand.
“It goes back and forth,” says Gary Meadows, a Washington State University pharmacy professor with nearly four decades researching nutrition and cancer. “Right now,” he adds, offering an example, “coffee is OK.”
For the consumer looking for food that might prevent disease, it’s a bewildering world. A quick scan of recent studies can turn up a trove of findings that are ambiguous, if not outright strange. You can eat flowers to reduce your cancer and heart disease risk. You can get more out of fiber, but that will depend on the type of bacteria in your gut. Are you a woman who mostly or always eats organic foods? Sorry, you have the same chance of developing cancer as other women.
To be sure, research on food and disease is often confounding for good reason. Living organisms are complicated, as are the hard-to-isolate effects of different food compounds over the time it takes for a disease to develop. What might seem striking in a petri dish or lab animal may play out differently in a human, if you can shoulder the massive expense of a human clinical trial.
Also, as Meadows explains, a disease like cancer can take many forms—and treatments.
Two people might both have prostate cancer, but one person’s cancer could be different from the other. The cancers have some gene defects in common, but not all. So while some nutrients might work on one of the cancers, they might not on the other. “And nutrients will work in some people,” says Meadows, “but not other people, because we’re all different.”
Still, amidst such devilish details and the high signal-to-noise ratio of solid findings and hype, WSU researchers are distilling a lot of new insights about food and health. This past December, Today Show host Matt Lauer noted that a study by WSU scientists “found out that organic milk contains a better balance of fatty acids that help keep our heart strong… One professor said all milk is good for us. It’s just that organic milk is better.”
He was referring to Chuck Benbrook, who led a team that documented how regular servings of mostly full-fat dairy products could dramatically improve one’s ratio of healthy and unhealthy omega-6 and omega-3 fatty acids.
Also on the organic front, in 2010 John Reganold and Preston Andrews found organic strawberries had more antioxidants, which may help the body prevent cell damage.
And two years ago, WSU researchers opened a new front against Campylobacter, one of the most common bacterial causes of food-borne illness in the United States and a major culprit in the rare paralyzing disorder Guillain-Barré syndrome. While their work was preliminary and removed from actual applications, they found that the compound diallyl sulfide was 100 times more effective in killing the bacterium than erythromycin and ciprofloxacin, two popular antibiotics. The source of this wonder drug: garlic.
The list of foods and beneficial food compounds under study at WSU runs the gastronomic gamut from staples like wheat, apples, and Cougar Gold cheese to exotic imports like purple Andean potatoes and quinoa. There has always been a connection between food and health—“you need to eat to stay alive,” says Meadows, noting the obvious. Now he and his colleagues are finding even more ways food can keep us going.
For Giuliana Noratto, the connection between food and health goes back to her home country of Peru.
“In our culture we believe that there are many foods that can help you prevent diseases,” says the food scientist. “Every Andean crop has a history behind it and it’s something that is going to help you.”
Among the bounty: maca, a tuber credited for, among other things, helping people stay sexually active into their 80s and 90s. “So it’s known as the Peruvian Viagra,” she says.
But there is a big difference between the claims of folk wisdom and verified science. Starting at the Universidad Nacional Agraria in Lima, Noratto has spent more than a decade investigating a variety of bioactive compounds as possible players in preventing and treating diseases like cancer and obesity.
She started with maca and the fellow tubers mashwa and oca, all regular parts of the rural Peruvian diet.
“All of those products have bioactive compounds,” she says. “And they are in a combination that apparently works well.”
Maca and mashwa have glucosinolates, sulfur-containing compounds that are also found in broccoli, which studies have shown can help prevent prostate cancer. Compared to a suite of potatoes acquired from the Lima-based International Potato Center, Noratto found “mashwa was the star of the group,” with twice the antioxidants of a purple potato, also no slouch in the antioxidant department. For her master’s work, she looked at vacon, a tuber eaten raw, and saw how it encourages good bacteria in the colon while lowering pathogenic ones.
She also tested the locally held belief that mashwa’s nutritional value improved if it was left out after harvest. It didn’t.
For her doctoral degree at Texas A&M, Noratto demonstrated that compounds in peaches slowed the growth of human breast cancers grafted on to mice. The tumors exposed to the compounds also lacked a lot of the blood vessel formation that helps cancer cells spread to other parts of the body. Scaled to a human, the peach polyphenol extract given the mice could be ingested by eating two or three peaches a day.
At WSU, Noratto has taken on an industrious portfolio of foods and compounds with a potential role in preventing obesity-related disease. One project involves examining apple compounds that go undigested high up in the digestive system. When they make it to the colon, they can serve as food for beneficial bacteria. She’s particularly interested in communities of bacteria found in lean mammals, with recent studies suggesting that different types of fecal bacteria can play a role in obesity.
So she cultured mouse feces, taking samples from obese and lean mice and fermenting them in extracts high in fiber and antioxidant phenolics from Washington-grown Granny Smith apples. The resulting bacterial communities looked more like those found in lean mice, suggesting that the apple compounds can help an obese animal get the healthier gut of a lean one.
Working with whole wheat, Noratto fed one group of obese mice a diet of whole wheat while feeding a control group the same calories, carbohydrate, protein, and fat in a diet of starch and protein. They ended up weighing the same, but the mice fed whole wheat had 18 percent less fat around their abdomen, one-third less fat under their skin, and even less in their hearts. They were also more active.
“There are trends basically relating a gluten-free diet to a healthier diet,” says Noratto, “but people are overlooking the fact that whole wheat contains other compounds that are beneficial and they can be depriving themselves of these good compounds.”
Boon Chew is something of a Renaissance man, with a bookshelf that includes a history of Procter & Gamble. Clownfish and damselfish mill about in a tropical aquarium on his desk. He’s long had diverse tastes in research, too, dating to his undergraduate days when he wrote a paper on the effects of nutrition on reproduction.
“Even from graduate school days, I always believed in a cross-disciplinary type of approach,” he says.
Three or four decades ago, that ran against science’s trend toward ever-finer degrees of specialization. But it happens to be one of the better ways to explore nutrition and its effects on physiology, where one needs to understand not just a food but its active compounds and their path from the fork to a specific set of changes in the body.
“We now understand how interconnected our systems are,”says Chew, a WSU food science professor. “Before, nutritionists didn’t even talk to physiologists. Now you know nutrition affects so many aspects, whether it has to do with the immune system, neurodegeneration, brain health, gut health.
“I have this grand picture,” he adds, “and this grand picture is foods and health. What we now call functional foods. But to get there, I have to show specific active compounds—bioactives, we call them—that could eventually drive what foods we study for promoting health.”
Case in point: cranberry juice.
For years, cranberry juice has been a popular home remedy for urinary tract infection. Its value is so commonly accepted that when Chew asks a class, “What comes to your mind when I say cranberries?” several students invariably say, “urinary tract infection,” if not, “UTI.”
But seven years ago, Chew could find no studies directly addressing the claim. Infecting people with harmful bacteria was not ethical or possible. So with funding from Ocean Spray, the juice cooperative, Chew led a randomized, double-blind study in which people drank cranberry juice or a placebo—Boon and his team of researchers didn’t know who had what. The study participants then gave samples of urine that the researchers used to treat infected urinary tract cells.
In an infection, bacteria need to stick to the cells they’re infecting. In the petri dishes of infected urinary tract cells, Chew and his team saw fewer sticky bacteria when they’d been exposed to cranberry-juice laden urine.
He saw visible changes in the bacteria as well. Fingerlike projections called villi help bacteria hook on to a cell. Using electron microscopes, Chew could see that bacteria exposed to cranberry-tainted urine had fewer, thicker villi, giving them less grip on a cell’s membrane.
He has since expanded his research to see if cranberry juice might also reduce inflammation, which is often associated with a host of problems, from gut health to cancer to rheumatoid arthritis. He had overweight but otherwise healthy people drink a cranberry beverage once a day for eight weeks, then analyzed their blood. They had less oxidative damage, better blood vessel function—an indicator of cardiovascular health—and less C-reactive protein, a marker of inflammation routinely used as an indicator of heart disease.
“We showed definitely that consumption of the beverage decreased inflammation,” says Chew.
While working on his doctorate in pharmacology, Gary Meadows isolated a yeast enzyme that metabolized tyrosine, an amino acid needed for tumors to grow. It got him thinking. Instead of giving mice the enzyme, he could give them a food—in this case, crystalline amino acids low in tyrosine.
It had a “profound effect” on reducing the spread of cancer, or metastasis, and prompted Meadows to look at nutritional approaches to cancer. He also started reviewing grant proposals in the field.
“That broadened my horizons,” he says one morning over a cup of antioxidant-rich green tea in his home on Pullman’s Sunnyside Hill. “I started seeing all sorts of different nutrients and constituents and people looking at their effects on cancer.”
Just a few years ago, after a career that includes being named a fellow of the American Association for the Advancement of Science, editors of the journal Cancer and Metastasis Reviews asked Meadows to search for foods that might play a role in reducing metastasis. Cancer kills, yes. But what really kills, he says, is its spread to other organs, overwhelming the body.
He spent months searching the medical literature, looking in particular for studies naming certain foods and known metastasis-suppressor genes. Oftentimes, the original researchers didn’t make the connection between the foods and the genes, but Meadows did, having acquired something of an encyclopedic knowledge of the genes and how they work.
He found more than 40 plant-based compounds that could slow the spread of cancer by turning on suppressor genes. Amino acids, vitamin D, ethanol, ginseng extract, the tomato carotenoid lycopene, the turmeric component curcumin, pomegranate juice, fish oil, and more all triggered suppression. It was a shopping list of cancer fighters, most of them available in the local grocery store, and they influenced gene expression in many cancers, including breast, colorectal, prostate, skin, and lung cancer.
“I know that there are a lot more things out there that will have an effect on metastasis suppressor genes,” he says. “They just haven’t been studied. And I think this is just a small list compared to what I feel will probably be a stronger list of compounds, but people haven’t specifically looked for those effects.”
That will take time. Meanwhile, Meadows understands the challenge consumers face as they undertake their own, less scientific sorting of information about healthy foods and habits.
“There are a lot of claims that are not backed up by strong clinical trials and evidence,” he says. “And those studies are very expensive and they’re long term studies, so we don’t get answers very rapidly.”
But there is a solid scientific basis to undertake a few good habits, he says. Statistics suggest that between one-fourth and one-third of cancers are diet related. Both high-calorie foods and a high-calorie diet increase the risk of certain cancers, as well as diabetes, heart disease, and other problems. In his search of metastasis-suppressor genes, Meadows saw weight loss also having a positive role. He also suggests eating less red meat, especially smoked meats, and more leafy vegetables and fruits.
“Then exercise is a real important component to the anti-cancer story,” he says. “Some of the strongest evidence we have in cancer prevention, at least in some cancers, particularly colon cancer, is exercise.”
And just because a food is good for you nutritionally, he cautions against nutritional supplements used in high doses for a pharmacological effect, which can be harmful. High doses of beta carotene for lung cancer, he says, can actually promote lung cancer.
“Now vitamin E has gotten a bad rap in terms of that as well,” he says.
“The best approach and the safe approach is to consume a variety of different foods—vegetables and fruits—that contain these anti-cancer compounds,” he says. “There’s a variety of compounds in these fruits and vegetables that work in a variety of different ways or mechanisms to impact either the initiation of cancer or progression. You need to attack cancer from every possible direction, the same way we use multiple drug therapies now.”
Meadows himself does what he can. Combined with other nutrients, that green tea he’s drinking increases the expression of a metastasis suppressor gene in certain prostate cancer cells. He puts turmeric on eggs for breakfast, has a thing for blueberries, and walks two to three miles a day. It’s not a marathon, but as he puts it, “You don’t have to be a marathon runner to get the benefits of exercise.”
Amid all his science, he is not above the adage: Everything in moderation.
“It seems to work,” he says.
Illustration
Eat well and fight cancer (PDF)
On the web
Overview of plant-based compounds that could slow the spread of cancer (PDF)