nos-trum. pronunciation: \nos'-trum\. noun. Etymology: Latin, neuter of noster our, ours.
1. a medicine of secret composition recommended by its preparer but usually without scientific proof of its effectiveness.
2. a usually questionable remedy or scheme.
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Sunday, January 9, 2011

Another Diet Book: Plant Foods...And Plant Foods Only (Yawn)

Interesting interview with a co-author of another diet book.  Clearly knows nutrition, but not so much about disease.

The China Study is a book based on 20 years of nutritional research in rural China and Taiwan.  The data purports to show that the population eating a plant-based diet were the healthiest.  You can read an interview with a co-author here (NY Times Well blog, Jan 7).

Based on that interview, I think the author, in advocating only plant food sources, violates his own principles, which I discuss below.  But for now, see this quotation from the interview:
"The problem is that we study one nutrient out of context. That’s the way we did research — one vitamin at a time, one mineral, one fat. It was always in a reductionist, narrowly focused way. But I learned that protein is not quite what we thought it was...What loomed large for me was that we shouldn’t be thinking in a linear way that A causes B. We should be thinking about how things work together. It’s a very complex biological system."
Well, yeah...but that applies to isolating plant food sources in the same way, doesn't it?

I haven't read the book, so I can't judge the overall claim.  For a critique of the book's conclusions go here

It's common sense that a balanced diet containing fruits and vegetables is healthier, and that Americans don't consume enough of this group of foods.  It's a much stronger statement to say that we should avoid all non-plant food sources.  The 500K people who bought the book are willing to consider it.

The anthropological evidence is that humans are omnivores, and have been from the beginning.  Not scavengers, really, but rather "un-picky" as a species.  It's speculated that this is why our appendix is vestigial, a word meaning "degenerate, persisting, but of no further use."  Many herbivores have GI tracts that process food in stages through serial digestion in multiple "stomachs" or pouches.  The appendix might be one of those (very speculative), and is now more of a problem (appendicitis), and not a benefit.

Even ignoring this, there's still no evidence that our bodies were designed to eat only plants.

But there is evidence that societies with a history of plant-based diets became so originally through necessity, not choice.  They ate animal foods when they could get it.

Plant-only nutrition requires some attention to diversity of source.  Single plant foods may be deficient in some building blocks for proteins and lipids required by the body.  The classic story for this diversity is the combination of corn and beans into menu items of Hispanic cooking.  Both corn and beans provide the amino acids missing from the other.  Maybe this story is apocryphal.

Some very restrictive plant food diets are deficient in protein.  You will hear vegetarians (often an ideological group) talk about needing protein supplements.

Trying to put all these books and diets into a reasonable course of action is a challenge.  I'm convinced that the more extreme the diet is, the less likely it is to be healthy in the long run.  So, I shy away from nutritional proposals that exclude entire food sources.  My sense is that all food sources bring something to the table (sorry).  Where we go wrong is in consuming too much of one thing; an overabundance of selected food types overwhelms our bodies' ability to burn or store the amount consumed.

And while our bodies evolved to handle a wide variety of foodstuffs (as omnivores), there was no need to evolve a way to handle too much food.

Not many Pre-history human societies had a problem with too many Burger Kings.

Doc D

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