Monday, October 01, 2007



Fat is no good, meat is no good and now carbohydrates are no good either

Obvious conclusion: Eat what you like -- your food will kill you anyway. Pesky how lifespans keep growing, though. Most people have a fair bit of variety in their diet (there is a variety of ingredients even in a Big Mac) so that is the situation which needs to be modelled. It rarely is, though. Only a dummy or a medical scientist would think that dietary components don't interact

Nutritionists call them carbohydrates. To most of us, they're simply sugars and starches. And although the fructose in soft drinks and the refined flour in white bread taste quite different, "nutritionally and metabolically they're the same as table sugar," explains endocrinologist David S. Ludwig. That's because the body digests all carbohydrate-rich foods into glucose, or blood sugar.

However, all carbs don't break down at the same rate. The body digests those in many whole-grain products quite slowly. Others become converted to glucose almost immediately. Rapidly digested carbs aren't healthy for people with diabetes and others watching their blood sugar. A new study by Ludwig and his colleagues at Children's Hospital Boston suggests that such carbs are also problematic for people looking to shed body fat. Indeed, the findings indicate that consumption of the wrong carbs can spur the development of body fat, even with no gain in weight.

In the study, mice that chowed down on a type of rapidly digestible starch didn't gain any more weight than did animals eating a starch that digests slowly. But the first group did accumulate lots of excess fat. The data indicate that something about rapidly digesting carbs signaled the body to convert more of a meal's energy into body fat, into fatty lipids that circulate in blood, and into deposits of fat throughout the liver.

Ludwig considers the observed effect on the animals' livers the most troubling one. Fatty-liver disease has traditionally been regarded as the first stage of damage from alcoholism that can progress to hepatitis, cirrhosis, and death. But researchers in recent years have discerned the beginnings of an epidemic of fatty-liver disease unrelated to alcoholism but correlated strongly with being overweight. Recent data suggest that as much as one-third of children and even a higher proportion of adults have the condition. Ludwig told Science News Online that he suspects that "up to half of the [U.S.] population" now has fatty-liver disease.

The question has been what's fueling this epidemic. Because the disease so often accompanies obesity, many researchers have suspected that high-fat diets and junk foods are responsible. Ludwig's group had another idea. In recent years, the mushrooming incidence of obesity in the United States has led to a push to get people to lower their intakes of fat. However, reducing fat consumption almost always translates into increasing the intake of carbs (see Counting Carbs). Moreover, the carbs most people reach for first are the refined-easy to digest-types found in white flour, white rice, pasta, and potatoes.

Ludwig's team decided to see whether a diet rich in a similar carb promotes fat buildup. They used a proportion of carbs that people on a low-fat diet might eat and compared its effects with that of a diet equal in all respects except that its carbs were mainly a slowly digested starch. In the September Obesity, the researchers show that animals eating rapidly digested carbs accumulated more fat throughout their bodies-including their livers-than did animals eating primarily the slow-to-digest starch. Says Ludwig, "This is the first study in which a single dietary factor-varied within normal ranges-affected whether the liver remained normal or accumulated seriously elevated levels of fat."

In the new study, Ludwig's team fed 18 recently weaned mice food pellets containing 13 percent fat, 19 percent protein, and 68 percent carbohydrates from corn starch. Half the animals got pellets containing the starch called amylopectin, which is made up of a string of glucose molecules that the gut easily degrades into sugar. The remaining mice ate pellets containing some amylopectin but mostly the starch called amylose. That type of corn starch resists breakdown in the gut.

All the animals ate and drank as much as they wanted for 25 weeks. Throughout the study, the researchers charted weight gain, body fat, fecal excretion of starch, and blood concentrations of glucose and insulin. At the end, the researchers killed the animals and measured their livers' fat contents.

Weight gain didn't differ between the two groups of animals, suggesting that the mice found the diets comparably palatable. However, the animals' bodies responded differently to the two food-pellet recipes. Mice dining on amylopectin-enriched chow became twice as fat as those eating the slower-digested amylose recipe. Mice eating this starch grew a little longer in body, so they looked leaner that the "roly-poly" mice eating easily digested starch, Ludwig says. The latter mice "felt squishy," whereas the slow-digested-starch eaters felt firm, he adds.

Although blood sugar concentrations didn't differ between the two groups, mice on the amylopectin-rich food developed higher insulin values after a meal. The body uses the hormone to shepherd energy into its cells. Higher blood insulin after a meal, Ludwig explains, indicates that an animal needs more insulin to fully use the food it's eaten. Needing more of the hormone can be a first sign of insulin resistance and impending diabetes.

Ludwig notes, "Insulin is a powerful anabolic hormone, meaning it promotes the storage of fat. In fact, that's arguably one of [the hormone's] main roles." One of the first places newly made insulin ends up is in the liver, where it can trigger the localized creation and stockpiling of fat. Although the rodents' livers weighed the same whether they ate fast- or slow-digested starch, fat made up 12 percent of the liver in mice fed the amylopectin-rich diet. That's double the fat content of livers in animals that had eaten the slow-digested starch. For perspective, Ludwig notes, people whose livers contain 10 percent fat are considered to be suffering from "advanced" nonalcoholic fatty-liver disease.

What about people?

This isn't the first study to indicate that foods that rapidly break down to glucose in the body-characterized as having a "high glycemic index" (see The New GI Tracts)-can fuel nonalcoholic fatty-liver disease. For instance, last year Silvia Valtuena of the University of Parma in Italy and her colleagues reported findings from a study of 247 apparently healthy men and women. The volunteers' diets were evaluated and given a glycemic-index (GI) rating.

Low GI foods included corn, dairy products, and fruit. High GI fare included bread, pizza, and baked snacks. The volunteers were grouped into four categories based on the ascending GI rankings of their diets.

Participants with the highest-GI diets were twice as likely to have undiagnosed fatty-liver disease as were other study participants. People in the highest group were also far likelier to be insulin resistant, the researcher reported in the July 2006 American Journal of Clinical Nutrition. [Epidemiological crap. Was social class controlled for?]

In an editorial accompanying the Valtuena report, David J.A. Jenkins and his colleagues at the University of Toronto argued that the "implication of this study is that a low-GI diet, or selection of lower-GI rather than higher-GI foods, may benefit persons with nonalcoholic fatty liver." Indeed, the commenters suggested, it might be possible for doctors to treat nonalcoholic fatty liver by lowering the glycemic index of an individuals' diets.

That's what Ludwig's group is now investigating: "We hope to enroll 46 kids to a diet for 6 months," he says. The 8- to 17-year-olds and their parents will receive dietary counseling. Half of the recruits will be assigned to a low-fat diet. The rest will receive counseling to lower the glycemic index of their diets. The general guidelines for a low-GI diet call for substituting whole-grain foods for ones made from highly processed cereal fibers and reducing refined sugars in favor of sweet fruits. "Conceptually," Ludwig says, "fatty liver should be reversible-we've seen it anecdotally in practice many times, such as when someone loses weight or changes the quality of their diet."

Source




Distracted? Tea might help your focus

Being a keen tea-drinker, I am not going to say anything bad about this report! A pity it did not actually involve tea though (See. I can't help myself!)

Many people reach for a cup of coffee when they need to concentrate. People with flagging focus might, however, get more bang for the buck with a cup of tea. Theanine, an uncommon amino acid found almost exclusively in tea, works with caffeine to boost the activity of brain neurons, new data show.

John J. Foxe of the Nathan S. Kline Institute for Psychiatric Research in Orangeburg, N.Y., and his colleagues recruited 16 people for tests of attentiveness on four days. Before testing, each individual drank a glass of water. On 3 days, the drink was spiked with 100 milligrams of theanine, 60 mg of caffeine, or both. The theanine dose was equivalent to that in 4 to 5 cups of tea, and the caffeine translated to about 2.5 cups of tea.

In the difficult tests, participants watched a computer screen and pressed a button when a designated shape appeared on the side of a busy visual field to which an arrow had previously pointed. Participants' accuracy differed little between days when they got water alone or with only one additive.

Accuracy improved dramatically, however, on the day that they got the theanine-caffeine combination. The attention benefit lasted throughout the 3 hours of testing. Brain activity, measured throughout each test, showed that theanine induced strong alpha waves in neurons, suggesting restfulness. But that lasted only until focus was required. Then, Foxe says, alpha activity dropped precipitously if a person had gotten theanine-especially in combination with caffeine-indicating that idling neurons had suddenly revved up their activity.

Source

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Just some problems with the "Obesity" war:

1). It tries to impose behavior change on everybody -- when most of those targeted are not obese and hence have no reason to change their behaviour. It is a form of punishing the innocent and the guilty alike. (It is also typical of Leftist thinking: Scorning the individual and capable of dealing with large groups only).

2). The longevity research all leads to the conclusion that it is people of MIDDLING weight who live longest -- not slim people. So the "epidemic" of obesity is in fact largely an "epidemic" of living longer.

3). It is total calorie intake that makes you fat -- not where you get your calories. Policies that attack only the source of the calories (e.g. "junk food") without addressing total calorie intake are hence pissing into the wind. People involuntarily deprived of their preferred calorie intake from one source are highly likely to seek and find their calories elsewhere.

4). So-called junk food is perfectly nutritious. A big Mac meal comprises meat, bread, salad and potatoes -- which is a mainstream Western diet. If that is bad then we are all in big trouble.

5). Food warriors demonize salt and fat. But we need a daily salt intake to counter salt-loss through perspiration and the research shows that people on salt-restricted diets die SOONER. And Eskimos eat huge amounts of fat with no apparent ill-effects. And the average home-cooked roast dinner has LOTS of fat. Will we ban roast dinners?

6). The foods restricted are often no more calorific than those permitted -- such as milk and fruit-juice drinks.

7). Tendency to weight is mostly genetic and is therefore not readily susceptible to voluntary behaviour change.

8). And when are we going to ban cheese? Cheese is a concentrated calorie bomb and has lots of that wicked animal fat in it too. Wouldn't we all be better off without it? And what about butter and margarine? They are just about pure fat. Surely they should be treated as contraband in kids' lunchboxes! [/sarcasm].

Trans fats:

For one summary of the weak science behind the "trans-fat" hysteria, see here. Trans fats have only a temporary effect on blood chemistry and the evidence of lasting harm from them is dubious. By taking extreme groups in trans fats intake, some weak association with coronary heart disease has at times been shown in some sub-populations but extreme group studies are inherently at risk of confounding with other factors and are intrinsically of little interest to the average person.


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3 comments:

le0dude said...

Yep, everything is banned now... nothing on this planet is good for you to eat lol! Well, i'd say you can eat whatever you want, just burn it off. I know burning off the fat is hard, but not really. If you put things into small goals you can just burn the fat easily, and lose weight quicker than ever! Nice blog!

NutritionPhD said...

The points you make are interesting as it shows that there has been some confusion in the general public re: the issue of weight and obesity. I am a scientist/nutritionist that does research in this area and would like to take the opportunity to address some of your points.

1). It tries to impose behavior change on everybody -- when most of those targeted are not obese and hence have no reason to change their behaviour.

-> Unfortunately, 2 out of 3 American adults are now classified as overweight and 1 out of 3 are obese. There is no doubt that this increase in obesity corresponds to increasing incidence of diabetes and heart disease among other diseases. Thus, public health initiatives are important as they are the only way to change this.

2). The longevity research all leads to the conclusion that it is people of MIDDLING weight who live longest -- not slim people. So the "epidemic" of obesity is in fact largely an "epidemic" of living longer.

->This is only somewhat true. Though people who are too skinny have been shown to have an avg shorter lifespan, life expectancy of an obese individual has been shown to be 7 yrs lower than a normal weight counterpart (Peeters et al). Additionally, for the 1st time in history, it has been suggested that the upcoming generation may have a shorter lifespan if the increasing trend in obesity continues (Olshansky et al).

3). It is total calorie intake that makes you fat -- not where you get your calories. Policies that attack only the source of the calories (e.g. "junk food") without addressing total calorie intake are hence pissing into the wind. People involuntarily deprived of their preferred calorie intake from one source are highly likely to seek and find their calories elsewhere.

->Yes but the question is often one of caloric density and volume. People who eat more junk (vitamin poor) food often eat more calories because there are more in a smaller amount of food. How much calories are in a fistful of popcorn vs. a fistful of chocolate chips?

4). So-called junk food is perfectly nutritious. A big Mac meal comprises meat, bread, salad and potatoes -- which is a mainstream Western diet. If that is bad then we are all in big trouble.

-> Unfortunately, it is also filled with saturated fats and contains more than 1/2 a days worth of calories in one meal!

5). Food warriors demonize salt and fat. But we need a daily salt intake to counter salt-loss through perspiration and the research shows that people on salt-restricted diets die SOONER. And Eskimos eat huge amounts of fat with no apparent ill-effects. And the average home-cooked roast dinner has LOTS of fat. Will we ban roast dinners?

-> Eskimos eat fat high in EPA and DHA, 2 types of fat that are good for you. Not the saturated fat high in the North American diet. We don't actually loose that much salt compared to how much we eat.

6). The foods restricted are often no more calorific than those permitted -- such as milk and fruit-juice drinks.

-> Milk has many vitamins and minerals not to mention, it is a perfect source of protein. Recommendations only ask you limit some foods not restrict them. BTW, fruit-juice drinks have very little actual juice and therefore, are asked to be limited.

7). Tendency to weight is mostly genetic and is therefore not readily susceptible to voluntary behaviour change.

->Our genes are not mutating as quickly as the rates of obesity are rising.

8). And when are we going to ban cheese? Cheese is a concentrated calorie bomb and has lots of that wicked animal fat in it too. Wouldn't we all be better off without it? And what about butter and margarine? They are just about pure fat. Surely they should be treated as contraband in kids' lunchboxes! [/sarcasm].

-> High fat cheeses should be limited as well as butter and margarine. Unfortunately, there are record highs of children getting diseases such as heart disease and diabetes that we did not routinely see 30 year ago. Thus, though fat should not be restricted in kids. They should be encouraged to be physically active (of which many are not) and taught proper eating habits.

Hope this clarifies.

jonjayray said...

Dear nutritionphd

Your screed is full of conventional but false assumptions. You have obviously not read the facts set out in my right-hand column for a start