by Carole Jackson, Bottom Line Health

If an apple a day can keep the doctor away, what can a kiwifruit — or several — do? Well, if one of your medical issues is high blood pressure, a new study finds that eating these fuzzy tropical fruits may do you some real good.

Does that make kiwi the new fruit phenom for heart health? I called Mette Svendsen, PhD, the study’s lead researcher, who works as a registered dietician at Oslo University Hospital in Norway. She told me that she had been intrigued by an earlier study performed by her research group that found that kiwi had a promising health effect in men who smoke (a group at higher risk for hypertension) — so they decided to put the fruit to the test among nonsmokers with blood pressure issues as well. Dr. Svendsen presented the study at the American Heart Association’s annual meeting in November 2011.

QUICK KIWI CURE?

Dr. Svendsen’s research randomly assigned 118 men and women with slightly elevated blood pressure or “prehypertension” to eat three kiwis or one apple a day for eight weeks. She and her colleagues chose to study three kiwis, in particular, to try to better match the calories in one apple. Measuring the participants’ blood pressure at the beginning of the study and at the end of the study with 24-hour automatic ambulatory blood pressure monitors, researchers observed that, after the eight-week study was over, the average systolic blood pressure reading for those who ate kiwis was 3.6 mm Hg lower than for those eating apples. And the average diastolic blood pressure reading for those who ate kiwis was 1.9 mm Hg lower than for the apple-eaters.

A drop of fewer than four systolic points may not seem like a big difference, but Dr. Svendsen said that it’s large enough to be “clinically significant” — meaning that it’s enough to make a small but tangible difference in people’s cardiovascular health. And since participants didn’t change anything else in their diets — and weren’t on blood pressure medications, which is why researchers chose to study those with only mildly raised blood pressure — Dr. Svendsen told me that she feels confident that kiwis can be a frontline defense in the battle to control blood pressure. But this study is only a start, she added, so more research on the topic needs to be done to confirm kiwi’s beneficial effects on heart health.

WHAT’S THE SECRET?

Kiwis are high in potassium, which is known to be helpful in controlling blood pressure, but Dr. Svendsen told me that her team believes the potent antioxidant lutein that is found in kiwis is probably what should get the credit in this case. She explained that lutein reduces free radicals by increasing nitric oxide, which may help keep blood vessels relaxed. Compared with apples, she said, kiwis have 10 times more antioxidants.

Kiwis may be considered a somewhat exotic fruit by many Americans, but they’re actually pretty inexpensive and easy to find, even in regular supermarkets. Buy them on the firm side (they last a while when stored at room temperature), and eat them when they begin to soften just a bit. You can peel them just as you would a cucumber or carrot — or some people prefer to cut them in half and scoop out the fruit with a spoon. Dr. Svendsen said that it doesn’t matter what time of day you eat your kiwis or whether you eat them on their own, sliced in a salad or smashed into a smoothie or juicer — the results are the same.

I asked whether taking a lutein supplement could work as a stand-in for eating kiwis for those who don’t like the fruits. Dr. Svendsen said probably not — “We haven’t studied the effect of taking a supplement, but other studies on antioxidant supplements have not been promising. It seems like the fruit itself is best.”

Source:

Mette Svendsen, PhD, RD, section for preventive cardiology, department of endocrinology, obesity and preventive medicine, Oslo University Hospital, Norway.

by Carole Jackson, Bottom Line Health

We Americans love our grilled meat, fish and poultry, whether from the backyard or in a restaurant — especially those blackened morsels on the edges of, say, a sizzling burger or barbecued ribs. In fact, we continue to eat our grilled meat even though it was discovered over the past two decades that charring meat produces distinctive chemicals that may raise our risk for colon, prostate or breast cancer. That’s love, folks! But now a study shows that this cancer risk may be even higher than we thought… maybe high enough to finally take the sizzle out of our grilling habit. Let’s see…

WHAT THE NEW GRILLING STUDY FOUND

Researchers from the Norwegian Institute of Public Health were concerned that previous studies on charred foods could be misleading because the kind of mice used in the studies do not metabolize the potentially dangerous substances in the same way that humans do. To correct this problem, researchers genetically engineered a group of mice to more closely mimic a human’s metabolism. (In particular, these mice were bred to have enzymes called sulfotransferases spread more widely within the digestive system, like humans have.)

Next, researchers injected a group of engineered mice and a control group of typical mice with a carcinogenic chemical called PhIP, which is formed in charred meats cooked at high temperatures — and the findings were dismaying. After 16 weeks, 31% of the typical mice had cancerous intestinal tumors — but in the engineered set, a whopping 80% did! In other words, the study concluded, humans may be more sensitive to the carcinogens found in charred meat than we previously thought.

AN EXPERT WEIGHS IN

To get perspective on the study, which was published in the October 17, 2011 issue of Molecular Carcinogenesis, I called molecular toxicologist Robert J. Turesky, PhD, research investigator at the Wadsworth Center, New York State Department of Health, in Albany. Dr. Turesky said that the study was interesting, but he thought that it is tenuous at best to extrapolate its findings to human risk. Among his reasons…

• The dosage of PhIP given to the animals was massive. Dr. Turesky said that it was “a million-fold, if not more” than humans would ever ingest per day.

• The mice received a PhIP compound that was not the natural form present in charred meat, but rather a synthetic chemical that is based on it.

• The researchers injected the chemical directly under the skin of the mice, which meant that the animals absorbed all of the chemical. When humans ingest PhIP, it is just one element in a complex mixture of many other chemicals, all of which influence how the body metabolizes and responds to compounds in foods — so humans don’t usually absorb 100% of PhIP.

• The injections were given to pregnant female mice just before they gave birth and then to those baby mice in the weeks shortly after their birth — times when the mice were particularly sensitive to carcinogenic chemicals.

SHOULD WE WORRY MORE?

You may be wondering why the researchers “stacked the deck” so much in the way they designed the study — but in fact, there was a good reason for what they did. Their goal was to see whether they were right to be concerned that the sort of laboratory mice commonly used for toxicological research (as opposed to their mice engineered to be more like humans) could have skewed the results of previous studies. In that goal, they seem to have succeeded — and now scientists are going to have to go back to their labs and design new studies with these and other animal models to see just how dangerous to us our beloved grilled meat really is.

Meanwhile, as Dr. Turesky noted, these results don’t mean that we should ignore the health issue altogether, because there is no doubt that charring meat can create human carcinogens. However, there are ways to minimize the formation of these chemicals in foods when you grill…

• Before grilling, marinate the food — even just 30 minutes is helpful — in marinades containing some combination of vinegar, lemon juice, tarragon, sage, mint and rosemary. There has been some evidence that this reduces the formation of carcinogens when grilling, though the data is still inconclusive, said Dr. Turesky.

• Flip meat on the grill frequently to minimize the burning of surfaces.

• Avoid eating well-done meat. The longer the meat is on the grill, the higher the possibility that PhIP will form.

• Eat lots of raw or lightly cooked vegetables with your meat. There is some evidence that cruciferous vegetables in particular (cabbage, broccoli, cauliflower, Brussels sprouts and others) are protective. They may change the way the body metabolizes chemicals produced by grilling and therefore cancel out at least some of the negative health effects of ingesting PhIP from cooked meats.

Now that Dr. Turesky has pointed out some of the shortcomings of the most recent study, I admit that I feel a little relieved. I know that frequently eating grilled meat isn’t the best dietary choice, but I’m not going to stop having the occasional grilled steak or chicken… and we’ll see what future research tells us.

Source(s):

Robert J. Turesky, PhD, research investigator at the Wadsworth Center, New York State Department of Health, Albany, and associate professor, School of Public Health, University at Albany, University of New York.