Joined up science

Usually, when the urge to blog comes over me, I can wait until the urge goes away and bothers someone else, or until enough time has passed to make the reason for the blog obsolete.

On this occasion, however, the urge hasn’t gone away and I hope you’ll forgive me for alerting your attention to an issue of New Scientist that you’ve probably already recycled.

In last week’s (19th January) edition, there were 3 clippings that I didn’t just collect, but stapled together. And they have been distracting me ever since.

The obvious one was on page 17. It was highlighted on the cover, so how could I miss it? Plugging his book, The Diet Delusion, journalist Gary Taubes ascertains that the ‘energy deficit = weight loss’ concept that has dominated the world of weight loss for the past 50 years or so is stifling our ability to solve the obesity problem. Taubes accuses nutritional science, in no uncertain terms, of basing its entire research and advice system on dogma, not science. This is a difficult accusation to bear for any scientific discipline, let alone one as complex as the science of human nutrition.

Taubes, however well-meaning he may be in alerting the New Scientist readership to the inconsistencies in the data and reminding us not to put all our eggs in one basket, does little more in his ‘comment and analysis’ than argue himself round in a circle. Essentially, he ends up still saying that obesity is a result of eating too much…just of the wrong things.

Taubes also sadly hadn’t seen the research on which Colin Barras’ piece on page 10 was based. Barras reports on work by William Bialek at Princeton University, who looks at living organisms as if they were computers. Success in life, according to Bialek, depends on an organism’s actions matching external conditions, using E. coli cells as a model for his theory. E. coli‘s ability to metabolise lactose hinges on expression of lac proteins, says Barras. Protein production being biologically expensive, bacteria that can match lac gene expression to the availability of lactose in their environment can capture the right amount of lactose and not waste protein by over-expressing. Whether or not the bacteria themselves are aware of responding to the environment is less relevant to nutritionists than to the biophysicists debating the issue. This environment-gene feedback also applies to obesity. Obesity is known to have a genetic component, but in the case of humans, deficiency in the ability to precisely match the storage of energy depending on its availability doesn’t deplete those genes from the pool. Obese people survive to maturity, reproduce and then survive some more, whatever the burdens on the healthcare services. As a solely genetic condition, it is unlikely that obesity would die out in the human population as it might do if it happened to bacteria.

Bacteria and diet got joint coverage again on page 15, where news of the ‘yogurt diet’ was announced. Jeremy Nicholson of Imperial College London has been playing with probiotics and a mouse model of the human gastrointestinal flora. Nicholson’s team has found a strain of Lactobacillus that help the mice to ‘poo out’ (technical term) fat. Those of you who have a subscription to ‘NutritionandFoodSciences.org’ might think this sounds familiar, especially when discussed in the context of obesity. On the 8th January 2007, we reported on work at Washington University’s School of Medicine that showed differences in the gut microflora of obese v. lean people (‘Gut Microbes And Obesity – Cause, Solution, Or Indication?‘). While this finding may have been a symptom rather than a cause of obesity, it is a useful reminder that the gut microflora does play an important role in nutrient digestion and absorption, as livestock nutritionists will testify from experience.

While I was looking for that last story on the gut microflora, browsing casually through the ‘In Brief and In Depth’ section armed only with ‘obesity’ as my search term, I was reminded just how varied the disciplines are within the science of nutrition. So, for Gary Taubes to imply that it is he, rather than nutrition, who is looking at all the facts sounds naїve at best. Even CAB Abstracts doesn’t have everything, though in its extensive coverage of obesity it has a significant enough share to be useful. Taubes can rest assured that nutrition is already working with all the little, scattered, pieces of several very large and complex jigsaw puzzles under the huge weight of public pressure to do something about obesity.

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