Warning on Tomatoes and Prostate Cancer

Photo: C.P. Storm/Creative Commons

Bad news: lycopene, an anti-oxidant found in large quantities in tomatoes, doesn't prevent prostate cancer.

Worse news: Beta-carotene might actually increase the risk of developing an aggressive form of prostate cancer, according to a study published in the journal Cancer Epidemiology Biomarkers & Prevention.

So men can stop stuffing themselves with tomatoes in the hopes of warding off prostate cancer.

Researchers carefully measured the amount of anti-oxidants in 28,000 men's blood, looked to see who among their study subjects developed prostate cancer and compared them to those who had not developed cancer. (This is called a case-controlled study and as such is not definitive but merits further exploration.)

The investigators found no evidence that lycopene offers any protection against developing prostate cancer.

At least, lycopene doesn't increase the risk of developing prostate cancer either.

Alas, the study investigators found that high levels of beta-carotene, a popular vitamin supplement, was linked to more cases of cancer that had spread beyond the prostate.

Whether beta-carotene actually causes the increased risk of aggressive prostate cancer is, of course, an open question that case-controlled studies, like this one, are not designed to answer. But the findings echo another beta-carotene study from 1996 that was randomized, double-blind and placebo-controlled (the most rigorous scientific study design available.) The 1996 study found that smokers who take even modest amounts of beta-carotene have a higher risk of lung cancer. Presumably the vitamin fueled the cancer's growth.

Next question, posed by Tom Paulson at the Seattle Post Intelligencer: Will Heinz stop marketing its Classico pasta sauce as one way to reduce men's risk of prostate cancer? (Kudos to Paulson for bringing up the advertising link, but he may want to brush up on the differences between lycopene and beta-carotene, which he confused in his article.)

Bottom line: Eating lots of vitamins or even lots of tomatoes won't make up for an unhealthy lifestyle. And even if you do everything right, you can still develop cancer. Tomatoes are food and should be enjoyed as food, not taken as medicine.

Sources: U Peters, et al. Serum Lycopene, Other Carotenoids, and Prostate Cancer Risk: a Nested Case-Control Study in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Cancer Epidemiology Biomarkers & Prevention 16, 962-968, May 1, 2007

GS Omenn, et al. Effects of a Combination of Beta Carotene and Vitamin A on Lung Cancer and Cardiovascular Disease. New England Journal of Medicine; Volume 334:1150-1155, May 2, 1996.

Businessman Arrested in Pet Food Scandal

With the arrest by the Chinese government of a local businessman for allegedly contaminating pet food ingredients with the industrial chemical melamine, the current food safety scandal has taken another turn--from the assumption of accidental contamination to growing evidence of deliberate behavior, from contamination of pet food to possible contamination of human food.

Ever notice how a particular story--like the melamine scandal or the death of Anna Nicole Smith--will keep showing up in the news? Journalists call this a story with legs.

In this case, the melamine scandal continues to resonate because it taps a growing fear of food that has become a hallmark of our globalized age. There was a time when food couldn't travel far without spoiling. Now fresh fruit from South America can fill the plates of North America out of season and for little cost.

Eating fruit is, of course, a very good thing. I wouldn't want to have to depend on all my food coming from local farmers and ranchers.

And yet, we're growing increasingly concerned about the long distances our food has to travel before it gets on our plates. What do we really know about the food we eat? Is shipping all this food long distances contributing to global warming?

In a sense, the many pets that have died from melamine contamination have served as the canary in the coal mine--an early warning system of something that has gone wrong.

Connecting the Dots on Food Safety

The best health articles, like the one Ariana Eunjung Cha wrote in the Washington Post Wednesday on the ongoing pet-food crisis, typically touch on the theme that you can't be healthy in isolation. What others do affects how healthy you are, just as what you do affects others.

Eunjung Cha connects the dots that link "food safety in China" to "food safety in the U.S." through the story of the recent melamine contamination of pet food products.

That sets the stage for these key observations from her article:

"With China playing an ever-larger role in supplying food, medicine and animal feed to other countries, recognition of the hazards has not kept up.

By value, China is the world's No. 1 exporter of fruits and vegetables, and a major exporter of other food and food products, which vary widely, from apple juice to sausage casings and garlic. China's agricultural exports to the United States surged to $2.26 billion last year, according to U.S. figures -- more than 20 times the $133 million of 1980.

China has been especially poor at meeting international standards. The United States subjects only a small fraction of its food imports to close inspection, but each month rejects about 200 shipments from China, mostly because of concerns about pesticides and antibiotics and about misleading labeling. In February, border inspectors for the U.S. Food and Drug Administration blocked peas tainted by pesticides, dried white plums containing banned additives, pepper contaminated with salmonella and frozen crawfish that were filthy."

Powerful stuff in an increasingly globalized economy.

Choosing Between A Healthy Diet And A Weight-Loss Diet

The word "diet" is the source of a lot of confusion in health stories. Sometimes it's about restricting your food intake to lose weight. Other times, it's about your regular food habits and their effect on your health. And sometimes it's about both. Not knowing the difference could lead you to an early grave.

A couple examples: a recent UCLA study concludes that dieting to lose weight leaves most people worse off than if they hadn't "dieted" at all. Meanwhile, a report in the Montreal Gazette talks about the challenges of following a "healthy diet" if you don't have a lot of money to spend on food.

And now, some quick guidelines to navigate the double meanings:

What you need to do to increase your chances of staying healthy typically starts with a daily habit of eating lots of fruits and vegetables and cutting down on saturated fat (like that found in ice cream and hamburger) combined with daily exercise--at least 30 minutes a day of brisk walking, jumping rope, swimming, dancing or other activities.

What you need to do to lose weight--and keep it off--starts with increasing your physical activity to at least 45 minutes a day most days of the week for the foreseeable future. Then you need to add more soluble fiber to your diet (real oatmeal, vegetables) so you won't feel as hungry (the fiber keeps the stomach from emptying too soon).

And yes, you might have to actually cut out certain foods, like ice cream or alcoholic beverages, to reduce your calorie count just enough to lose a pound or two a week at most. Any more than that, and you're in danger of packing the pounds right back in a matter of months because your "diet" is not sustainable.

Lots of Juice Linked to Obesity

We're constantly being bombarded by messages about health--like this photo I snapped of the side of a truck, advertising the POM brand of fruit juices and tea. Notice how the "O" in POM is shaped like a heart. Must be good for you--right? After all, fruits are good for you; they're full of anti-oxidants and all that good stuff.



But fruit juices are also full of calories. Sixteen ounces of POM (480 ml) is 320 calories, for example. You'd have to eat at least three pomegranates (at 105 calories apiece) to get the same calorie-count as in one bottle of POM juice.

Chances are you wouldn't eat three pomegranates in a row. But it's pretty easy to drink 16 oz of POM juice--that's just two glasses. Our bodies don't notice calories in liquid form; liquids don't fill us up the way solid food does. So it's very easy to overindulge on fruit juices.

Indeed, a recent study from Deakin University in Australia found that children who consume just over 16 ounces (500 ml) of fruit drinks a day were more likely to be overweight or obese. And those who drank more than 25 ounces (750 ml) were twice as likely to be overweight or obese.

Now as I've said before, an association doesn't prove cause and effect. It doesn't prove that drinking lots of juice is what caused these children to be overweight. (Also, I haven't been able to find the original study, just press accounts.) But in this case, particularly given the calorie counts, it should make you mighty suspicious.

Bottom line: fruit is better than fruit juice. If you drink fruit juices, limit your consumption.

See also obesity prevention program at Deakin University in Australia.

Atkins vs. Ornish vs. Real Life

The best recap I've read of the new study showing that women who tried to follow the Atkins diet lost slightly more weight in the course of a year than those who stuck with three other diet plans comes from Denise Gellene at the Los Angeles Times. In it she zeroes in on this salient fact:

Lead author Christopher D. Gardner, a Stanford University assistant professor of medicine . . . said he suspected that the bulk of the weight loss in the Atkins program came from women substituting water for soft drinks.

Which brings up the point that what actually makes a difference in any diet plan and what the promoters of that diet plan say makes a difference are not necessarily the same thing. In other words, you don't actually have to follow the Atkins plan to take advantage of this healthy tip: don't drink your calories!

Gellene also got at the difference between dieting to lose weight (typically a short-term goal) and eating healthfully for the long term. Eating more fruits and vegetables, cutting down on saturated fat (marbly steaks, ice cream), avoiding processed foods and not drinking your calories--all while getting plenty of exercise--are still your best bets for longterm health.