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| DALLAS, July 25 -- Lipogenesis increased significantly when glucose was replaced with fructose on a gram-for-gram basis in energy drinks consumed by six healthy volunteers, researchers here found. Action Points
Conversion of fructose to lipid occurred quickly, usually within four hours after ingestion, Elizabeth Parks, Ph.D., of the University of Texas Southwestern Medical Center, and colleagues reported in the June issue of the Journal of Nutrition.
Moreover, consumption of a high-fructose drink for breakfast increased liver-mediated fat storage after lunch, the researchers said.
"Our study shows for the first time the surprising speed with which humans make body fat from fructose," said Dr. Park. "Once you start the process of fat synthesis from fructose, it's hard to slow it down."
The findings provide strong support for clinical guidelines that recommend limiting processed carbohydrates, which often contain high-fructose corn syrup, she added.
Studies involving controlled feeding have shown that fructose could increase serum triacylglycerol levels and maintain the increase throughout the day in healthy individuals and in patients with diabetes. Chronic elevation of triacylglycerol levels could lead to accumulation of atherogenic lipoprotein remnants, the authors said.
Replacement of glucose with fructose in a fat-containing breakfast drink has been shown to increase the four-hour appearance of the meal's fatty acids in VLDL, suggesting increased reesterification of breakfast fat in the liver, they continued.
So the authors hypothesized that a fructose-induced rise in lipogenesis in the morning would further increase triacylglycerol concentrations following lunch. They also sought to determine the lipogenic effects of two different doses of fructose in healthy, relatively lean individuals.
Four men and two women volunteered for the study. Their mean age was 28 and they had a mean body mass index of 24.3 and mean serum triacylglycerol level of 1.03 mmol/L.
On separate days, the volunteers consumed breakfast energy drinks sweetened with 100% glucose, a 50-50 mix of glucose and fructose, and a 25-75 mix of glucose and fructose. The volunteers ate a standardized lunch four hours after consuming the drink.
Lipogenesis was assessed by serial testing for four hours after breakfast, and postprandial lipemia was measured following the lunch meal.
The drink containing only glucose led to a peak fractional lipogenesis of 7.8%. In contrast, the 50-50 mix and the 25-75 mix more than doubled peak fractional lipogenesis (15.98% and 16.9%, respectively, P<0.02).>
Fructose consumption at breakfast induced a dramatic rise in postprandial lipemia after the lunch meal. Consumption of the fructose-containing drinks was associated with an increase in postprandial serum triacylglyerols of 11% to 29% compared with the glucose-only drink.
Concentrations of triacylglycerol-rich lipoproteins increased by 76% to 200% with the 50-50 and 25-75 mix of glucose and fructose.
"The message from this study is powerful because body fat synthesis was measured immediately after the sweet drinks were consumed," Dr. Parks said. "The carbohydrates came into the body as sugars, the liver took the molecules apart . . . and put them back together to build fats. All this happened within four hours after the fructose drink. As a result, when the next meal was eaten, the lunch fat was more likely to be stored than burned."
The message should not be misconstrued by people who are trying to lose weight, she continued. Specifically, they should not eliminate dietary fruits, which have high fructose concentrations.
Overeating and excess caloric consumption remain the principal drivers of weight gain and obesity, she concluded.
The biggest limitation of the study, the researchers acknowledged, is its small sample size. However, they said, the repeated measures design supports the notion that the differences were real and would be reproducible.
Another limitation is the fact that the drinks were consumed first thing in the morning when participants were in the fasting state. That could lead to an underestimation of lipogenesis.
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| Primary source: Journal of Nutrition Source reference: Parks EJ, et al "Dietary sugars stimulate fatty acid synthesis in adults" J Nutr 2008; 138: 1039-1046. |
To judge by recent headlines, coffee could be the latest health-food craze, right up there with broccoli and whole-wheat bread.
But don't think you'll be healthier graduating from a tall to a venti just yet. While there has been a splash of positive news about coffee lately, there may still be grounds for concern.
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Hector Sanchez for The Wall Street Journal Source: WSJ research
This month alone, an analysis in the Archives of Internal Medicine found that people who drink three to four cups of java a day are 25% less likely to develop Type 2 diabetes than those who drink fewer than two cups. And a study presented at an American Association for Cancer Research meeting found that men who drink at least six cups a day have a 60% lower risk of developing advanced prostate cancer than those who didn't drink any.
Earlier studies also linked coffee consumption with a lower risk of getting colon, mouth, throat, esophageal and endometrial cancers. People who drink coffee are also less likely to have cavities, gallstones, cirrhosis of the liver, Parkinson's disease and Alzheimer's disease, or to commit suicide, studies have found. Last year, researchers at Harvard University and the University of Madrid assessed data on more than 100,000 people over 20 years and concluded that the more coffee they drank, the less likely they were to die during that period from any cause.
But those studies come on the heels of older ones showing that coffee—particularly the caffeine it contains—raises blood pressure, heart rate and levels of homocysteine, an amino acid in blood that is associated with stroke and heart disease. Pregnant women who drink two or more cups of coffee a day have a higher rate of miscarriages and lower birth-weight babies; caffeine has also been linked to benign breast lumps and bone loss in elderly women. And, as many people can attest, coffee can also aggravate anxiety, irritability, heartburn and sleeplessness, which brings its own set of problems, including a higher risk of obesity. Yet it's just that invigorating buzz that other people love and think they can't get through the day without.
Why is there so much confusion about something that's so ubiquitous? After all, some 54% of American adults drink coffee regularly—an estimated 400 million cups per day—and coffee is the second most widely traded commodity in the world, after oil.
WSJ's health columnist Melinda Beck discusses new evidence that drinking coffee may help prevent diseases such as prostate cancer, Alzheimer's and diabetes.
For starters, the vast majority of coffee studies to date have been observational, in which researchers examine large sets of data over many years, looking for patterns in peoples' habits and their health.
But subjects don't always remember or report accurately on how much they drink. Cup sizes can range from 6 to 32 ounces; caffeine loads can vary from 75 to nearly 300 milligrams. Loading up with sugar, flavored syrup and whipped cream can turn a no-fat, almost no-calorie drink into the equivalent of an ice-cream soda.
Even carefully constructed observational studies that correct for such variables can only find correlations, not prove a cause-and-effect relationship. There may be other, hidden reasons why people who drink a lot of coffee have a lower risk of illness—such as jobs that provide a steady income and access to health care, exercise and healthier food. Conversely, "people who don't feel that healthy may be less likely to drink six cups of coffee a day. ... It's just a possibility," says Jim Lane, a psychophysiologist at Duke University Medical Center who has studied the effects of caffeine for more than 25 years.
Indeed, many studies from earlier decades that linked coffee drinking to a higher risk of cancer were apparently detecting related habits instead. Once researchers started adjusting for study subjects who also smoked cigarettes, the additional cancer risk disappeared.
"When I went to medical school, I was told that coffee was harmful. But in the '90s and this decade, it's become clear that if you do these studies correctly, coffee is protective in terms of public health," says Peter R. Martin, a professor of psychiatry and pharmacology at Vanderbilt University and director of the school's Institute for Coffee Studies, founded in 1999 with a grant from coffee-producing countries.
Still, many researchers believe that the only way to draw firm conclusions about something like coffee is through experimental trials in which some subjects are exposed to measured doses and others get a placebo, with other variables tightly controlled. When that's been done, says Duke's Dr. Lane, "the experimental studies and the [observational] studies are in very sharp disagreement about whether caffeine is healthy or not."
His own small, controlled studies have shown that caffeine—administered in precise doses in tablet form—raises blood pressure and blood-sugar levels after a meal in people who already have diabetes. Other studies have found that caffeine and stress combined can raise blood pressure even more significantly. "If you are a normally healthy person, that might not have any long-term effect," says Dr. Lane. "But there are some groups of people who are predisposed to get high blood pressure and heart disease and for them, caffeine might be harmful over time."
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Epidemiologists counter that such small studies don't mirror real-world conditions, and they can't examine the long-term risk of disease.
The prostate-cancer study, for example, compared the coffee-drinking habits of 50,000 men working in medical professions with their incidence of prostate cancer over 20 years, and also took into account family history of prostate cancer and how frequently they had screenings. Roughly 5,000 of the men developed prostate cancer during that period, including 846 cases of the most advanced and lethal kind. But the more cups of coffee the men drank, the less likely they were to be in that most lethal group. "You can't do a randomized controlled trial on men starting in their 20s and following them until they are old enough to get prostate cancer," says lead investigator Kathryn Wilson, a research fellow in epidemiology at Harvard School of Public Health. "For some of these questions, observational studies are the best we are going to get."
As for diabetes, at least 18 studies have found that drinking three or more cups of coffee a day is linked with a lower risk of developing the disease. The more such findings are repeated, particularly with different populations, the stronger the evidence is.
In both the prostate and diabetes studies, the health benefits were found for caffeinated as well as decaffeinated coffee, suggesting that some other component in coffee is responsible. Coffee contains traces of hundreds of substances, including potassium, magnesium and vitamin E, as well as chlorogenic acids that are thought to have antioxidant properties.These may protect against cell damage and inflammation that can be precursors to cancer, diabetes, neurological disorders and cardiovascular disease.
One theory gaining credence is that some of those beneficial components may counterbalance some of the harmful effects of caffeine. For example, while caffeine keeps people awake in part by blocking adenosine, a brain chemical that brings on sleep, the chlorogenic acid in coffee keeps adenosine circulating in the brain longer.
And while caffeine seems to boost adrenaline that primes the body for action, coffee itself may have a calming effect. Even the aroma of coffee beans can help ease stress in rats, researchers at Seoul National University in South Korea showed in a study in the Journal of Agricultural and Food Chemistry last year. Chlorogenic acid also slows the release of glucose into the bloodstream after a meal, which may counteract caffeine's glucose effect.
"It's a yin and yang effect," says Vanderbilt's Dr. Martin, an addiction psychiatrist who also notes that former alcoholics who drink coffee are more apt to stay sober than those who don't. Even though these studies are just associations, he says, "they may provide leads for us to better understand some of the most common illnesses that affect mankind as well as developing ways to treat them. But everything is cloaked in 'mays.' "
Most researchers agree that there isn't enough evidence about the benefits of coffee to encourage non-coffee drinkers to acquire the habit. And no one has come close to finding a recommended number of cups per day for optimum health. People's reactions to coffee are highly individual. One small cup can give one person the jitters while others can drink 10 cups and sleep all night.
At the same time, people who love coffee probably don't need to worry that they are harming their health by drinking it -- unless they already have high blood pressure or are pregnant or are having trouble sleeping, in which case it's prudent to cut down.
Even Dr. Lane, who thinks the risks of caffeine outweigh coffee's potential benefits, concedes he drinks several cups a day. "Why do I do it?" he muses. "I ask myself that question ..."
—Email healthjournal@wsj.com.Correction & Amplification:
Peter R. Martin, a professor at Vanderbilt University School of Medicine and director of the Institute for Coffee Studies there, is an addiction psychiatrist. An earlier version of this column incorrectly stated that he is an addiction psychologist.
Red wine has long been touted as a health elixir. Now wine's purported health-giving ingredient, resveratrol , is available in daily supplements, beverages and even a new nutritional bar claimed by sellers to help you live longer and help prevent cancer and other diseases. Until recently, the evidence for resveratrol has been animal data, but preliminary human testing has yielded intriguing results.
wsj, Dec 22, 209
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Tim Foley Resveratrol is a substance found in grapes and other plants. Many of the supplements on the market extract it from the Japanese knotweed plant, which is a plentiful and inexpensive source. Switzerland's Royal DSM NV sells a synthetic version called resVida, which is found in supplements, a nonalcoholic fruit-flavored beverage and the new Winetime chocolate-fruit bar.
Resveratrol has found been found in animal studies to prevent or slow progression of illnesses from cancer to cardiovascular disease—and even to extend the life span of some organisms. Since 2008, at least five human studies have been presented at scientific meetings showing human benefits, ranging from improved blood flow to the heart to better control of diabetes.
The newest results are exciting, but some scientists say it is too early for the public to begin taking supplements, which contain as much resveratrol in one pill as dozens or hundreds of bottles of wine, depending on the dose. The proper dose for humans isn't yet known—and more isn't necessarily better.
Researchers at the University of Connecticut School of Medicine in Farmington found that lower doses of resveratrol protected rats' hearts from artificially induced heart attacks while high doses actually made the attacks worse.
While some safety studies have been conducted on humans, it is too early to know if there are long-term side effects of high doses, says S. Jay Olshansky, a professor of epidemiology at the University of Illinois at Chicago. "I cannot emphasize enough: Do not experiment on your own body," he says.
Joseph C. Maroon, a neuroscientist at the University of Pittsburgh Medical Center who has written a book on resveratrol, agrees that more studies are needed but doesn't think it's unreasonable to take a moderate dose of resveratrol. "I don't see any significant downside," he says.
Dr. Maroon says animal data suggest 50 to 1,000 milligrams a day is an effective dose; he takes 300 milligrams daily—which he says contains the amount of resveratrol in some 150 bottles of wine.
No one knows exactly how resveratrol works, but scientists believe it activates a wide range of genes, creating a cascade-like effect on a variety of body functions. Human data include a 100-person placebo-controlled study by Sirtris Pharmaceuticals Inc. that found lowered blood-glucose levels in diabetics who took the GlaxoSmithKline unit's proprietary formulation, SRT501, not yet on the market.
A 19-person study presented earlier this month at a British scientific conference, sponsored by Royal DSM, found that "flow mediated dilation," a measure of cardiovascular health, increased an hour after taking resVida. At an American College of Sports Medicine conference last year, Dr. Maroon and colleagues reported that a three-month study of 51 people found a resveratrol-containing supplement not currently on the market increased endurance on a stationary bicycle compared with a placebo, and also increased verbal memory scores on a standardized test.
And in a report published earlier this month in the journal Optometry, researchers found that five months' therapy with a Longevinex, a supplement sold by Resveratrol Partners LLC of Las Vegas, resulted in significant improvement of vision of an 80-year-old man who was having difficulty with night driving. The visual measures were subjective but researchers also found a significant decrease in lipofuscin, a granular substance that builds up in aging tissues and is linked to vision decline, says researcher Stuart Richer, chief of optometry at the Veterans Affairs Medical Center in North Chicago. Resveratrol Partners provided the supplements taken by the patient, says Dr. Richer, and he has agreed to conduct a company-funded 24-person follow-up study.
One person isn't enough to prove resveratrol can help age-related vision decline, says Dr. Richer, but "we want to do this in a controlled situation with many patients."
