Rice consumption and health

Carbohydrate-rich foods lead to the formation of blood sugars after digestion (e.g., glucose, fructose), which are then used by the liver to synthesize liver glycogen. Liver glycogen is essentially liver-stored sugar, which is in turn used to meet the glucose needs of the human brain – about 5 g/h for the average person.

(Source: Wikipedia)

When one thinks of the carbohydrate content of foods, there are two measures that often come to mind: the glycemic index and the glycemic load. Of these two, the first, the glycemic index, tends to get a lot more attention. Some would argue that the glycemic load is a lot more important, and that rice, as consumed in Asia, may provide a good illustration of that importance.

A 100-g portion of cooked rice will typically deliver 28 g of carbohydrates, with zero fiber, and 3 g of protein. By comparison, a 100-g portion of white Italian bread will contain 54 g of carbohydrates, with 4 g of fiber, and 10 g of protein – the latter in the form of gluten. A 100-g portion of baked white potato will have 21 g of carbohydrates, with 2 g of fiber, and 2 g of protein.

As you can see above, the amount of carbohydrate per gram in white rice is about half that of white bread. One of the reasons is that the water content in rice, as usually consumed, is comparable to that in fruits. Not surprisingly, rice’s glycemic load is 15 (medium), which is half the glycemic load of 30 (high) of white Italian bread. These refer to 100-g portions. The glycemic load of 100 g of baked white potato is 10 (low).

The glycemic load of a portion of food allows for the estimation of how much that portion of food raises a person's blood glucose level; with one unit of glycemic load being equivalent to the blood glucose effect of consumption of one gram of glucose.

Two common denominators between hunter-gatherer groups that consume a lot of carbohydrates and Asian populations that also consume a lot of carbohydrates are that: (a) their carbohydrate consumption apparently has no negative health effects; and (b) they consume carbohydrates from relatively low glycemic load sources.

The carbohydrate-rich foods consumed by hunter-gatherers are predominantly fruits and starchy tubers. For various Asian populations, it is predominantly white rice. As noted above, the water content of white rice, as usually consumed by Asian populations, is comparable to that of fruits. It also happens to be similar to that of cooked starchy tubers.

An analysis of the China Study II dataset, previously discussed here, suggests that widespread replacement of rice with wheat flour may have been a major source of problems in China during the 1980s and beyond ().

Even though rice is an industrialized seed-based food, the difference between its glycemic load and those of most industrialized carbohydrate-rich foods is large (). This applies to rice as usually consumed – as a vehicle for moisture or sauces that would otherwise remain on the plate. White rice combines this utilitarian purpose with a very low anti-nutrient content.

It is often said that white rice’s nutrient content is very low, but this problem can be easily overcome – a topic for the next post.

Olympic buzz: Road to London as Merritt speaks on Pistorius

Olympic buzz: Merritt speaks on Pistorius

One quick thought today, to keep the Olympic momentum going, as we're now only 71 days away from the Olympic Games.  The story is LaShawn Merritt commenting on Oscar Pistorius, which is noteworthy mainly because it's the first time that anyone has voiced a concern over Pistorius' participation and potential advantage.  And yes, it's "only" Merritt, but it's the first salvo in what is likely to be an ongoing debate on one of the biggest stories of this Olympic Year.

It's also a topic I've covered extensively in the last few years, because it's one of the biggest sports science stories in athletics (with Caster Semenya being the other), and so in need of scientific understanding.  Merritt's statements are thus the catalyst to bring up an "old" topic, and if you've read this before, feel free to give it a miss this time!

Before I get into the Merritt comments, might as well post these links for those who might be interested in reading more on the research.  These five links explain it in about as much detail (but in a simplified way) as I think is possible for a complex case.  I have no doubt that I will be referring to these links over and over in the next 71 days 

1. A statement by Peter Weyand and Matthew Bundle explaining the confusing background to the case, and why they knew immediately that he had an advantage, but it didn't come out until 18 months later
2. A second statement by Weyand and Bundle, this time expanding on the science of why Pistorius has a large advantage during sprinting - it concerns the mass of the blades and never seen before sprinting mechanics
3. My first post on the advantage of Pistorius - setting up the theory and providing the evidence from the first round of testing
4. Part 2 of the series, this time looking at the CAS evidence that had Pistorius cleared, and how it was deplorable science to manipulate the finding
5. Part 3 of the series - the Weyand/Bundle analysis, which finds that Pistorius has a large advantage because of lighter limbs, faster swing times and less force

By way of background, links 1 and 2 were actually written in response to my 3-part series (links 3 to 5), because Peter Weyand and Matthew Bundle had read the posts, and wanted to put their own case across.  It was also symptomatic of the media coverage, because Weyand had been interviewed numerous times about Pistorius, but clearly felt unable to get his viewpoint across to journalists who frankly didn't care for scientific integrity, but rather wanted to tell a heart-warming story.

Weyand and Bundle thus wrote those two statements at the end of 2011, to attempt to get the scientific facts and truth out.  Hopefully the lazy media pay attention in 2012.

LaShawn Merritt speaks on Oscar Pistorius

LaShawn Merritt has become a polarizing figure in athletics, because of his ban for doping two years after he tested positive for the steroid hormone dehydroepiandrosterone.  His defence?  He'd taken a penis enlargement drug, and he served a 21-month ban.  He was then involved in a legal case that would eventually see an IOC rule that would have prevented him from competing in the Olympic Games scrapped, and he will defend his Beijing gold in London.  That certainly makes Merritt a controversial figure, and his statements this past week on Pistorius will only add to the controversy.

Briefly, in this interview, Merritt raised concerns that Pistorius' carbon fiber blades might one day allow him to outrun able-bodied competitors.  Merritt recounts a story of a Paralympic double-amputee who reportedly improved by 2 seconds within a few months as a result of a slight increase in leg length (this is a common story, incidentally, which I have heard from other sources for a number of athletes - small changes in prosthetic limbs produce large improvements in performance).  Merritt's concern, then, is that technology is constantly improving, and he has encouraged the authorities to monitor the situation.

Now, the merits of Merrit's (sorry) position can be debated.  Many will say that he's a drug cheat and should be dismissed out of hand (as many of you did on Twitter).  And while I can certainly see that Merritt's views may not be credible, I think that's a) missing the point, and b) a parallel issue - I'd be hesitant to hear Merritt out if he's talking about doping and the dangers of supplement use, but this is a different issue.  It's too easy to shoot the messenger.  I think it's more important to ask whether "what" they are saying may be true, rather than attacking "who" is saying it.

Having said this, I'd argue that Merritt's reasons for speaking now are perhaps slightly off - it should not solely be a case of "let him run for now but if he gets too fast then stop him".  I've always argued that the principle, not the performance or the person, should be the key factor.  It is an interesting question, however, as to how authorities would ensure that advancements in technology don't take the 2009 blades and improve them to the tune of 2 seconds.  Again, prototypes are constantly being introduced, and anyone who believes that the "blades are the same as the ones from 1996" (as Pistorius has claimed in interviews) is delusional about technology and the commercial influence driving its progress.  Indeed, Prof Hugh Herr, one of the scientists instrumental in getting Pistorius cleared (more on the "science" used for this below) is the beneficiary of an enormous amount of money from Ossur, Pistorius' prosthetic blade sponsor, specifically to help develop better prosthetic limbs that will one day outperform human limbs.  So technology does move forward, but this is an interesting side note.

To me, Merritt speaking out is interesting, because it's the first time anyone with profile has spoken up about what is such an emotive topic that many are hiding out of fear of the fall-out, should they dare suggest anything is amiss about Pistorius.

The issue is thus not one of "trusting" Merritt, or believing him, it's really just of interest that the "off-limit" topic has been broached.  I just wish that more scientists and experts would comment publicly, because opinion may be far stronger than what has been reported.  The media coverage of Pistorius has been overwhelmingly emotive, with the science almost always being downplayed - journalists seem to accept as gospel the simple answer provided to their often very simple questions.  Few are asking the difficult questions about the process that cleared Pistorius, and the only "scientists" who are speaking out are Hugh Herr and the rest of the CAS research team that cleared him.  The Weyand-Bundle research is never properly examined, and nor do independent scientists comment on that scientific process and debate.  The end result is a hall of smokescreens and mirrors, and the Pistorius PR machine rolls on, convincing editors and journalists that there is no advantage.

The science: Head vs Heart

The opposite may in fact be true, if only the media would really interrogate what happened at CAS, what the researchers did and get to the bottom of that "scientific research".  It would also help if the scientific community projected its opinions outwards, rather than internally.  Recently, we hosted a visiting scientist at our university.  Their area of expertise is tendons and movement.  They presented video footage of tendons under load, and spoke of how elasticity, fatigue and energy return would impact on performance.  It is amazing to see how similar animal limbs are in appearance and function to the carbon fiber blades worn by Pistorius.  

So an obvious question after this presentation is what they feels about Pistorius?  They refused to answer this, responding more or less as follows "I have strong views on that, but I don't want to state them publicly.  My head says one thing, my heart says another".  In other words, "I know what I believe, but I'm not prepared to face the potentially hostile reaction, so I choose rather to stay silent".  That to me is abdicating a professional responsibility because of a fear of public reaction.  It's showing that truth is less important than perception, and that to me is a cowardly response from science, and I would extend this to say that in general, the science has been "cowardly" on this issue - it has, since the beginning, been "someone else's problem", until eventually, that "someone else" was only ever going to speak in favour of Pistorius, regardless of what the evidence showed.  I would argue that people in positions of intellectual influence have a responsibility to speak out, regardless of the perception and reaction - if it's true, then say it.  That's the driving ethos of this site, but perhaps that is just me.  

As Pistorius embarks on his European season, needing to run the A-qualifying standard once to make the SA team, this debate is bound to spark up again.  It's a fascinating one, and not least of all because of the science vs ethics debate.  I can fully appreciate the conflict, and I even respect the position of those who argue that Pistorius should run despite the advantages because he is an inspiration (he is) who is good for the sport (he may be), and because he's the only one and is not winning.  I disagree with the viewpoint, but I can respect why people might say it.  But what I can't agree with is one that says "there is no advantage", because in three rounds of scientific testing, not a single thing has been found that disproves the theory that he has an advantage.  Whether it is metabolic, energetic, mechanical, or fatigue related, every single piece of evidence confirms the theory and hypotheses, and points to a large advantage.  So the "no advantage" argument is wrong.  

Then there's also the process by which the testing was conducted, poorly managed at first, then challenged, possibly manipulated and then the legal process that saw only half the data presented to CAS before a decision was made.  From A to Z, this was a case in bad science meets PR and law.  And that looks set to continue into August.

Ross

The 2012 Arch Intern Med red meat-mortality study: The “protective” effect of smoking

In a previous post () I used WarpPLS () to analyze the model below, using data reported in a recent study looking at the relationship between red meat consumption and mortality. The model below shows the different paths through which smoking influences mortality, highlighted in red. The study was not about smoking, but data was collected on that variable; hence this post.

When one builds a model like the one above, and tests it with empirical data, the person does something similar to what a physicist would do. The model is a graphical representation of a complex equation, which embodies the beliefs of the modeler. WarpPLS builds the complex equation automatically for the user, who would otherwise have to write it down using mathematical symbols.

The results yielded by the complex equation, partly in the form of coefficients of association for direct relationships (the betas next to the arrows), have a meaning. Some may look odd, and require novel interpretations, much in the same way that odd results from an equation describing planetary motions may have led to the development of the theory of black holes.

Nothing is actually "proven" by the results. They are part of the long and painstaking process we call "research". To advance new knowledge, one needs a lot more than a single study. Darwin's theory of evolution is still being tested. Based on various tests and partial refutations, it has itself evolved a great deal since its original formulation.

One set of results that are generated based on the model above by WarpPLS, in addition to coefficients for direct relationships, are coefficients of association called "total effects". They aggregate all of the effects, via multiple paths, between each pair of variables. Below is a table of total effects, with the total effects of smoking on diabetes incidence and overall mortality highlighted in red.

As you can see, the total effects of smoking on diabetes incidence and overall mortality are negative, but small enough to be considered insignificant. This is interesting, because smoking is definitely not health-promoting. Among hunter-gatherers, who often smoke tobacco, it increases the incidence of various types of cancer (). And it may be at the source of many of the health problems suggested by analyses on the China Study II data ().

So what are these results telling us? They tell us that smoking has an intermediate protective effect, very likely associated with its anorexic effect. Smoking is an appetite suppressor. Its total effect on food intake is negative, and strong. As we can see from the table of total effects, just below the two numbers highlighted in red, the total effect of smoking on food intake is -0.356.

Still, it looks like smoking is nearly as bad as overeating to the point of becoming obese (), in terms of its overall effect on health. Otherwise we would see a positive total effect on overall mortality of comparable strength to the negative total effect on food intake.

Smoking may make one eat less, but it ends up hastening one’s demise through different paths.