The Logic of Nutrition

According to the Whole Grains Council, “Every day, more and more studies show the benefits of whole grains.” This statement isn’t a surprise, coming from folks whose slogan is Whole Grains at Every Meal.

To assist us, they have compiled a list of studies showing just how healthful whole grains are.

Before I even examined this list, I predicted that these studies would use the same deeply flawed “grains are healthy” logic as displayed in the reports that whole grains reduce the incidence of Type 2 diabetes. Today’s misguided nutrition logic that says “if A can be shown to be better than our carefully controlled B, then an abundance of A is obviously beneficial to everyone.”

Let’s take a look at a couple of their cited studies in a little more detail.

Weight Loss, Decreased Fat with Whole Grains

Journal of Nutrition, Feb 22, 2012. [Epub ahead of print] (Kristensen et al.)

The Whole Grain Council reports:

Switching to whole grains may reduce body fat and aid heart health, according to scientists at the University of Copenhagen. In a twelve-week, randomized clinical trial, they asked 79 overweight or obese postmenopausal women to eat a calorie-restricted diet incorporating either 480 calories of refined grain foods or the same amount of whole grain foods. Those eating the diet with whole grains lost more weight (3.6kg vs 2.7kg) and saw a more significant decrease in body fat (3% reduction vs 2.1%) compared to those eating refined grains. Cholesterol levels increased 5% in the refined group, highlighting the heart benefits of choosing whole grains instead of refined.

The researchers examined the health improvements created by replacing 480 calories worth of refined wheat with 480 calories whole wheat. It’s immediately clear that this is not showing that whole wheat is healthful, it’s just showing that whole wheat isn’t as harmful as refined wheat—hardly a surprising scientific breakthrough.

Here are some relevant statements from the study abstract:

  • “Body weight decreased significantly from baseline in both the RW (-2.7 ± 1.9 kg) and WW (-3.6 ± 3.2 kg) groups, but the decreases did not differ between the groups.” [emphasis mine]

What this statement says is that the refined wheat group lost between 0.8 and 4.6 kg while the whole wheat group lost between 0.4 and 6.8 kg. The authors’ observation that the “decreases did not differ between the groups” means that even though some in the whole wheat group lost more weight than some in the refined wheat group, there wasn’t any statistically significant difference between the weight lost between the two groups. (For you statistics-minded readers, the correlation’s P-value was 0.11. A P-value this high supports the authors’ assertions that there was no statistically relevant difference between the groups.)

This is quite a different statement than the Whole Grains Council’s announcement that “those eating the diet lost more weight (3.6 kg vs 2.7 kg)…” It’s blatantly misleading for the Whole Grains Council to cite only the average weight loss, ignore the range of the weight loss indicated, and ignore the authors’ conclusion that weight loss “decreases did not differ between the groups.”

  • “The reduction in body fat percentage was greater in the WW group (-3.0%) than in the RW group (-2.1%).”

Yes, according to the researchers, the whole wheat group lost a staggering 0.9% more body fat than the group eating refined wheat. Does a less than 1% difference in fat loss sound headline worthy to you?

  • “Serum total and LDL cholesterol increased by ~5% in the RW group but did not change in the WW group.”

Wait a minute! The whole grains didn’t improve cholesterol? A study cited by the Whole Grains Council on the benefits of whole grains shows that whole grains didn’t improve cholesterol?!??!?? Oh, I see. Looking back at the Whole Wheat Council’s comment “Cholesterol levels increased 5% in the refined group, highlighting the heart benefits of choosing whole grains instead of refined.” Once again, only in comparison to something worse does whole wheat, which doesn’t improve cholesterol at all, look good.

And finally, the conclusion from the abstract:

  • “In conclusion, consumption of whole-grain products resulted in a greater reduction in the percentage fat mass, whereas body weight changes did not differ between the RW and WW groups. Serum total and LDL cholesterol, two important risk factors of cardiovascular disease, increased with RW but not WW consumption, which may suggest a cardioprotective role for whole grain.”

Summarizing, whole wheat:

  • …didn’t affect weight loss
  • …resulted in a less than 1% increase in body fat lost
  • …did not improve cholesterol at all

Only in the crazy, spin-doctored world of today’s backwards nutrition advice can no difference in weight loss and a <1% improvement in body fat loss be a deemed a success. Similarly, it seems that only in the logic of Alice’s Wonderland could zero improvement in cholesterol be deemed cardioprotective.

Moving on to another study…

Subsequent Meal Effect and Glucose Control

Journal of Nutrition and Metabolism, 2012; 2012:829238. [Epub Oct. 30 2011] (Higgins)

The Whole Grain Council reports:

Eating whole grains or legumes at one meal not only reduces surges in glucose after that meal, but also after the next meal eaten. Eating whole grains or legumes at breakfast helps control blood sugar after lunch, for example, and eating either or both at dinner can reduce the blood sugar rise of the next morning’s breakfast. Since this effect may explain why eating whole grains and legumes can reduce diabetes risk, this paper describes the possible mechanisms of the subsequent meal effect.

This paper is a review article. A review article reports on a group of related studies; it doesn’t report upon research conducted specifically for that paper. This review focuses upon studies that examine the glucose-lowering effects of adding whole grains and legumes to meals.

The conclusion of this article, based upon the authors’ examination of the cited studies, is that the “ingestion of whole grains and legumes may cause diminution of postprandial glycemia not only at the meal in which they were consumed but also at subsequent meals.

To study this review article, it is necessary to examine some of the specific studies cited, beginning with the first one:

D. J. Jenkins, T. M. Wolever, R. H. Taylor et al., “Slow release dietary carbohydrate improves second meal tolerance,” American Journal of Clinical Nutrition, vol. 35, no. 6, pp. 1339–1346, 1982.

The researchers in this study showed, rather unsurprisingly, that the postprandial glucose rise from a “relatively low glycemic effect” meal was dramatically lower than the glucose rise from the “high glycemic effect,” meal. The low glycemic carbohydrate meal raised the postprandial glucose peak by only an average of 15 mg/dL (0.8 mmol/L) while an equivalent number of carbohydrates from a “high glycemic effect” meal resulted in an average increase of four times the glucose peak, or 59 mg/dL (3.3 mmol/L).

Are we terribly surprised? Is it really surprising that low glycemic carbohydrates raise glucose levels less than high glycemic carbohydrates?

What were the foods that the researchers used, anyway? What was the high glycemic carbohydrate? Was it refined white sugar? Perhaps refined white bread?

No. The “high glycemic effect” carbohydrate the researchers selected was “wholemeal bread,” otherwise known as whole wheat bread.

That’s right, the high glycemic carbohydrate was whole wheat bread, heralded in the first study cited by the Whole Grain Council as a weight-reducing, fat-reducing, cardioprotective food.

And yet this study calls whole wheat bread a high glycemic food and uses it as the unfavorable comparison against which the more healthful, low glycemic carbohydrate measured.

How can this be?

Because the first study compares whole wheat bread to refined wheat bread and, “Ta Da!” the whole wheat bread comes out on top (albeit not by much) whereas this study compares whole wheat bread to lentils and shows that the exalted whole wheat bread produces on average four times the rise in postprandial glucose levels.

(By the way, assuming an average fasting glucose of 85 to 100 mg/dL (with most adults today being in the upper end of that range, if not higher) the average glucose rise from the 100 g of whole wheat bread in this study is enough to increase most anyone’s glucose level above 140 mg/dL, or into the range where blood glucose is toxic to internal organs.)

To recap what the Whole Grain Council has told us so far:

  • Using the Kristensen et al. study, the Whole Grain Council argues that whole grains are healthful because whole wheat bread is better than that horrible refined wheat bread
  • Using the Wolever  et al. study, the Whole Grain Council argues that whole grains are healthful because lentils are better than that horrible whole wheat bread

Are you starting to feel like a kid at a magic show trying to follow the disappearing coin? One moment it’s behind your ear and the next, it’s up the magician’s sleeve.

It’s nutritional sleight of hand at its finest.

Don’t blink or you’ll miss it!

The rest of the studies in this “subsequent meal effect” review article all follow the same approach: compare an intentionally high glycemic meal to one that is low glycemic and show that participants have a lowered glucose response to the low glycemic meal. Comparisons used in the other studies include:

  • Comparing low glycemic red lentils to a mixture of pure glucose and soy protein (it takes a room full of PhDs to show that eating lentils produces a lower blood glucose response than eating pure glucose?)
  • Comparing refined white bread to a mixture of barley fiber and unrefined barley bread (You’ll never guess what happened: The mixture of barley fiber and unrefined barley bread produced less of a glucose response than the refined white bread! Wow. How surprising.)
  • Refined white bread versus unrefined barley kernels (hmmm, that’s a toughie. I can’t imagine what’s going to happen there.)
  • Refined white bread mixed with corn flakes compared to a high-fiber cereal
  • Spaghetti mixed with refined white bread versus spaghetti mixed with high-doses of barley fiber

This isn’t rocket science, gang. Does it surprise you that low glycemic foods raise glucose levels less than high glycemic foods? The science doesn’t surprise me. The resulting inane recommendations do.

The Whole Grain Council bets heavily that the average consumer cares only about sound bites and will never dig deeply enough to realize that controlling the comparison paints whatever picture they want to paint.

“If A is better than B,” they tell us, “be sure and eat plenty of A.” In an interview on CBS This Morning! show, Dr. William Davis refers to this as “the logic of nutrition.”

While I was working on this piece, my seven-year-old daughter walked into my office and I posed the following question to her:

“If hitting yourself in the head with a small rock hurts far less than hitting yourself in the head with a large rock, wouldn’t you rather hit yourself in the head with a small rock?”
She responded, “I’d rather not hit myself in the head with a rock at all.”

I told her that with thinking like that she’ll never work for the Whole Grains Council.

With your newfound eye for “the logic of nutrition,” take a look at some of the other studies on the Grain Council’s site and see what other nutritional sleight of hand you find.

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