Monday, October 11, 2010

Those wicked fizzy drinks again

Fizzy drinks ("pop", "soft drinks") are regularly attacked by the obesity warriors because they are allegedly very calorific. Though milk, which is also highly calorific, gets a pass, for some reason.

The attack does not end there, however, there is also an unhappy band who attack fizzy drinks not only because they are sweet but because the particular sweetener in them is particularly naughty: Meet the fructose warriors. The article below is an introduction to the controversy and I will add a few further words at the bottom of it -- JR

Dr. Robert Lustig, professor of pediatrics at the University of California at San Francisco, is the star of the video above. While he presents some material that’s scientifically sound, he also makes enough errors to warrant a healthy dose of criticism. There’s a ton of material he goes over, so instead of writing a multi-chapter opus, I’ll discuss the aspects that I feel are the most relevant and interesting.

Bravo, Doc

Lustig’s delivery is clear, confident, charismatic, and engaging overall. I’m sure many would think that his style is annoyingly smug and preachy, but I find it entertaining. This is a good thing, since the video is about 90 minutes long. Amidst the folly that prompted this post, he offers a few good observations.

First off, he makes a valid point that the public health movement against dietary fat that started in the early 1980′s was a grandiose failure. The climb in obesity to epidemic proportions over the last 30 years is plenty of evidence for this. It was also accurate of him to cite the significant increase in overall caloric consumption over this same time period. Furthermore, he shows an interesting progression of Coca-Cola’s 6.5 oz bottle in 1915 to the 20 oz bottle of the modern day.

Lustig acknowledges the First Law of Thermodynamics as it applies to changes in bodyweight. He attacks the vague expression that “a calorie is a calorie” by pointing out that different nutrients impart different physiological effects and have different roles within the body. His concluding recommendations included kicking out liquid calories except milk, which is generally a good strategy for children. Okay, so far so good. But what does he say that’s so misleading? Let’s take a look.

Boooo, Doc

While Lustig correctly points out that the nation’s overall caloric consumption has increased, he proceeds to blame carbohydrates as being the primary constituent. The thing is, he uses data spanning from 1989-1995 on children aged 2-17. Survey data is far from the gold standard of evidence, but if you’re gonna cite it, you might as well go with something more recent that includes adults.

Here’s the latest from the USDA Economic Research Service (ERS), which tracked the percent of total daily calories of the range of food groups from 1970-2007. The actual spreadsheet of the following figures can be downloaded here, click on the “Percents” tab at the bottom [1]:

* Meats, eggs, and nut kcals decreased 4%.

* Dairy kcals decreased 3%.

* Percentage of fruit kcals stayed the same.

* Percentage of vegetable kcals stayed the same.

* Flour and cereal product kcals increased 3%.

* Added fat kcals are up 7%,

* Added sugars kcals decreased 1%

* Total energy intake in 1970 averaged 2172 kcal. By 2007 this hiked up to 2775 kcal, a 603 kcal increase.

Taking a hard look at the data above, it appears that the rise in obesity is due in large part to an increase in caloric intake across the board, rather than an increase in carbohydrate in particular.

Lustig insufficiently addresses the ‘energy out’ side of the equation. According to the research, it’s possible that over the last couple of decades, we’ve become more sedentary. King and colleagues recently compared the physical activity data in the National Health & Nutrition Examination Survey (NHANES) from 1988-1994 with the NHANES data from 2001-2006, and found a 10% decrease [2]. From a personal observation standpoint, that figure seems conservative (internet surfing for hours after your desk job shift, anyone?). It’s safe to say that all 603 extra daily calories have been landing in the nation’s collective adipose depot.

It’s also safe to say that all this finger-pointing at carbohydrate is just as silly as the finger-pointing toward fat in the ’80′s. Lustig takes the scapegoating of carbohydrate up a notch by singling out fructose. Perhaps the most passionate point he makes throughout the lecture is that fructose is a poison. Well, that’s just what we need in this day and age – obsessive alarmism over a single macronutrient subtype rather than an aerial view of the bigger picture.

Fructose is evil, context be damned

So, is fructose really the poison it’s painted to be? The answer is not an absolute yes or no; the evilness of fructose depends completely on dosage and context. A recurrent error in Lustig’s lecture is his omission of specifying the dosage and context of his claims. A point he hammers throughout his talk is that unlike glucose, fructose does not elicit an insulin (& leptin) response, and thus does not blunt appetite. This is why fructose supposedly leads to overeating and obesity.

Hold on a second…Lustig is forgetting that most fructose in both the commercial and natural domain has an equal amount of glucose attached to it. You’d have to go out of your way to obtain fructose without the accompanying glucose. Sucrose is half fructose and half glucose. High-fructose corn syrup (HFCS) is nearly identical to sucrose in structure and function. Here’s the point I’m getting at: contrary to Lustig’s contentions, both of these compounds have substantial research showing not just their ability to elicit an insulin response, but also their suppressive effect on appetite [3-6].

But wait, there’s more. In studies directly comparing the effect of fructose and glucose preloads on subsequent food intake, one showed no difference [7], while the majority have shown the fructose preload resulting in lesser food intake than the glucose preload [8-10]. A recent review of the literature on fructose’s effect on satiety found no compelling case for the idea that fructose is less satiating than glucose, or that HFCS is less satiating than sucrose [11]. So much for Lustig’s repeated assertion that fructose and fructose-containing sugars increase subsequent food intake. I suppose it’s easier to sensationalize claims based on rodent data.

In the single human study I’m aware of that linked fructose to a greater next-day appetite in a subset of the subjects, 30% of total daily energy intake was in the form of free fructose [12]. This amounts to 135 grams, which is the equivalent of 6-7 nondiet soft drinks. Is it really that groundbreaking to think that polishing off a half-dozen soft drinks per day is not a good idea? Demonizing fructose without mentioning the dose-dependent nature of its effects is intellectually dishonest. Like anything else, fructose consumed in gross chronic excess can lead to problems, while moderate amounts are neutral, and in some cases beneficial [13-15].

I’m obviously not in favor of replacing anyone’s daily fluid intake with soft drinks, but I can already see a number of straw man arguments headed my way. This is because people have a tendency to think in either-or terms that strictly involve extremes. I’ll quote an elegant review by independent researcher John White that echoes my thoughts [16]:

Although examples of pure fructose causing metabolic upset at high concentrations abound, especially when fed as the sole carbohydrate source, there is no evidence that the common fructose-glucose sweeteners do the same. Thus, studies using extreme carbohydrate diets may be useful for probing biochemical pathways, but they have no relevance to the human diet or to current consumption.

Atkins, Japan, & alcohol – oh my!

One of Lustig’s opening assertions is that The Atkins diet and the Japanese diet share one thing in common: the absence of fructose. This is flat-out false because it implies that the Japanese don’t eat fruit. On the contrary, bananas, grapefruits, Mandarin oranges, apples, grapes, watermelons, pears, persimmons, peaches, and strawberries are significant staples of the Japanese diet [17]. Lustig’s claim also implies that the Japanese do not consume desserts or sauces that contain added sucrose. This is false as well.

Another oversimplification Lustig makes is that fructose is “ethanol without the buzz,” and that fructose is toxic to the liver. This once again helps me illustrate my point that even in the case of alcoholic beverages, their risk or benefit to health is dose-dependent. Just like his extremist treatment of fructose, Lustig bases his case on the effect of chronic isolated ethanol consumption in large doses. It’s easy to examine ethanol out of its normal context within beverages such as wine, because then you can conveniently ignore the evidence indicating its potential health benefits when consumed in moderation [18].

Partial redemption

Towards the end of Lustig’s lecture, he mentions that fructose within fruit is okay because its effect is neutralized by the fiber content. To a degree, this is a valid claim. However, in building this stance, he uses sugarcane to illustrate just how fiber-dominant natural sources of fructose are, and this is the exception rather than the rule. He claimed that, “Wherever there’s fructose in nature, there’s way more fiber.” That statement is far from universally true. Drawing a few common examples from the major fruits consumed in Japan, a midsize banana contains roughly 27 total grams of carbohydrate, 7 grams of fructose and 3 grams of fiber. A midsize apple contains 25 total grams of carbohydrate, 12 grams of fructose and 4 grams of fiber. Two cups of strawberries contains 24 total grams of carbohydrate, 4 grams of fructose, and 6 grams of fiber.

I would add that fiber is only one of the numerous phytochemicals in fruit that impart health benefits. Thus, it’s not quite as simple as saying that fructose is evil, but once you take it with fiber, you’ve conquered the Dark Side.

Summing up

I have a great deal of respect for Lustig’s professional accomplishments, and I share his concern for the nation’s penchant for sitting around and overconsuming food and beverages of all sorts. However, I disagree (as does the bulk of the research) with his myopic, militant focus on fructose avoidance. He’s missing the forest while barking up a single tree.

So, what’s the upper safe limit of fructose per day (all sources considered)? Again, this depends on a number of variables, not the least of which are an individual’s physical activity level and lean body mass. Currently in the literature is a liberal camp reporting that fructose intakes up to 90 grams per day have a beneficial effect on HbA(1c), and no significant effects are seen for fasting triacylglycerol or body weight with intakes up to 100 grams per day in adults [15]. The conservative camp suggests that the safe range is much less than this; roughly 25-40 grams per day [19]. Figuring that both sides are biased, the middle figure between the two camps is roughly 50 grams for active adults.

Although the tendency is to get hung up on the trivial minutia of an exact gram amount, it’s not possible to issue a universal number because individual circumstances vary widely (this is a concept that baffles anti-fructose absolutists). The big picture solution is in managing total caloric balance with a predominance of minimally refined foods and sufficient physical activity. Pointing the finger at fructose while dismissing dosage and context is like saying that exercise should be avoided because it makes you fat and injured by spiking your appetite and hurting your joints.

SOURCE. Follow-up discussion here.

Canada has half the obesity incidence of the USA yet fructose is the main swetening agent in Canadian fizzy drinks too. And Australia uses sucrose (from sugarcane) almost exclusively in its drinks yet falls roughly half way between Canada and the USA in obesity.

Epidemiology is never positive proof of anything but is pretty persuasive as disproof and the comparison between the three rather similar countries that I have just quoted does not at all fit the pattern that the fructose fanatics would predict. Only a double blind study would settle the matter but the epidemiology hardly encourages such a study

I personally would be pleased if the fructose warriors were right. I come from sugarcane country in Australia and a ban on fructose would no doubt do wonders for my home town. Sugar from sugarcane is pure sucrose

UPDATE: I probably should note that sucrose is a naturally-occurring molecule in its own right. The fact that it can be analysed as a combination of fructose and glucose does not mean that it has to be produced that way nor does it mean that it has the same properties as those simpler molecules. If the lusty one wants to ban sucrose because fructose forms part of its chemical makeup he is in effect trying to ban all the major natural sweeteners -- which is nuts -- JR

Now it's beetroot juice!

It appears to give elite athletes a tiny extra edge but drinking a lot of it has unpleasant side effects

When Chris Carver ran an ultra-marathon in Scotland last year, which challenges athletes to run as far as possible within 24 hours, he ran 225 kilometres.

Determined to do better in this year's race, Carver added something extra to his training regime: beetroot juice. For a week before the race, he drank the dark purple juice every day. Last month, Carver won it by running 238 kilometres. "The only thing I did differently this year was the beetroot juice," said Carver, 46, a professional runner based near Leeds, in northern England.

He said more exercise would have improved his endurance, but to get the same result he attributes to the juice - an extra 13 kilometres - it would likely have taken an entire year.

Some experts say adding beetroot juice to your diet could provide a performance boost even beyond the blood, sweat and tears of more training.

In two studies conducted at Exeter University on 15 men, Stephen Bailey and colleagues found cyclists who drank a half-litre of beetroot juice several hours before setting off were able to ride up to 20 per cent longer than those who drank a placebo blackcurrant juice.

By examining the cyclists under a scanner that analyses how much energy is needed for a muscle to contract, Bailey and colleagues discovered beetroot juice allows cyclists to exercise using less oxygen than normal.

"The beetroot juice was effective even without any additional training," Bailey said. "It reduces the energy requirements on your muscles so you can last longer." While the beetroot juice was provided free by its manufacturer, Exeter University paid for the research.

Bailey said the high nitrate content of beetroot juice is responsible for its athletic benefits. Scientists aren't exactly sure how it works, but suspect having more nitric oxide in your body, a byproduct of nitrate, helps you exercise with less oxygen. Bailey said the same effects might be possible if people ate more nitrate-rich foods like beetroot, lettuce or spinach.

Bailey and colleagues calculated beetroot juice could translate into a 1 to 2 per cent better race time, a tiny improvement likely only to matter to elite athletes. They are still tweaking the dosage but say athletes should consume the juice a few hours before training so their body has time to digest it. Their latest study was published in June in the Journal of Applied Physiology.

"Drinking beetroot juice is not going to turn a recreational runner into an Olympic champion, but it might make tolerating more exercise easier so you can train more," said Dr Andy Franklyn-Miller, a sports medicine expert at the Centre for Human Performance in London. He was not connected to the research and has not received any funding from beetroot juice makers.

Franklyn-Miller said since people often reach an athletic plateau where more training doesn't help, beetroot juice could give you an extra edge you wouldn't get otherwise. "It's not banned, so there's no reason not to try it," he said. Still, he warned drinking too much of the juice could lead to side effects like abdominal cramps, diarrhea or purple urine.

Previous studies in Britain and the US have found beetroot helps the heart by lowering blood pressure.

Other experts warned manipulating your diet can't replace the benefits of training. "Certain foods can help you maximise the benefits from exercise, not reduce the amount you're doing," said Roger Fielding, director of the Nutrition, Exercise Physiology and Sarcopenia Laboratory at Tufts University. He was not connected to any research on beetroot or any other nutritional supplements.

For serious athletes, Fielding said changing your diet could help. "If a very small improvement is valuable to you, it's possible something like beetroot juice could do that," he said.

Other studies have shown drinking things like pickle juice or having a small carbohydrate snack during a marathon, can prevent cramps and improve performance. Scientists have also found cherry juice, which helps reduce exercise-induced swelling, could be strong enough to reduce some athletes' use of anti-inflammatory pain medication.

Fielding said the benefits of beetroot juice and other foods and drinks could have wider benefits and might one day be used to help elderly people with muscle weakness.

Some elite athletes warned beetroot juice may not be to everybody's taste. "A few of my friends think it's really disgusting," said Colin McCourt, 25, a British runner competing at the Commonwealth Games in New Delhi this month.

In April, McCourt started drinking cherry and beetroot juice, which he credits with helping him train longer and more often. "I feel like I get a benefit from it, even if it's minimal," he told Associated Press Television.

McCourt said he will continue to adjust his training regimen in preparation for the London 2012 Olympics, but plans to maintain his juice habit. "There will be a lot more beetroot juice if my stomach can take it."


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