Saturday, September 14, 2013

The Nutrition Debate #143: Fruit Consumption & Diabetes – a Theater of the Absurd Construct

No sooner had I posted column #138, “Fruit, the 3rd Rail for Prospective Low Carb Dieters,” when my Medscape Alert brought me this absurdist piece: “Consumption of Certain Fruits Linked to Lower Diabetes Risk.” It knocked me back on my heels. How could the consumption of any food, including all fruit, whose principal macronutrient is just simple sugars, “lower diabetes risk”? Am I living in an incomprehensively illogical world? A world without meaning? Has the respected research community abandoned rational thinking, I asked? I had to read the piece.

The report was from the Department of Nutrition, Harvard School of Public Health, and appeared in an online article in BMJ, the British Medical Journal. The Medscape write-up was authored by Joe Barber, Jr. PhD, who wrote, “Increasing fruit consumption has been recommended for the primary prevention of many chronic diseases, including type 2 diabetes, although epidemiologic studies have generated somewhat mixed results regarding the link with risk of type 2 diabetes.”

But here, in my opinion, is where the study author’s logic went awry. “The inconsistency among these studies may be explained by differences in types of fruits consumed in different study populations as well as difference in participants' characteristics, study design, and assessment methods, although a meta-analysis did not show that the associations differed by sex, study design, or location." Okay, all epidemiological studies inherently have many confounding factors and biases, but the hypothesis proposed to address these factors is, IMHO, also inherently flawed. Just because “differences in types of fruits consumed” was not previously studied, does not lead to the conclusion that the types of fruit consumed are differentiating, even if only associative, criteria. True, the authors cache the hypothesis carefully in the word “may,” but that did not similarly constrain the report’s conclusions, or the gushing headlines.

The authors’ conclusion: "Overall, these results support recommendations on increasing consumption of a variety of whole fruits, especially blueberries, grapes, and apples, as a measure for diabetes prevention." Utterly unbelievable!

The article received funding from the National Institutes of Health and was published on August 29th. It immediately was picked up and ‘broadcast’ in such places as The Guardian, Science Daily, Medical News Today, The Huffington Post, the Daily News, and The lede in the e! Science News piece was, “Eating more whole fruits, particularly blueberries, grapes, and apples, was significantly associated with a lower risk of type 2 diabetes, according to a new study led by Harvard School of Public Health (HSPH) researchers.” How can a humble blogger compete with a headline like that?

The only redeeming message in the “study” was the lede in a few more circumspectly edited pieces:  Greater consumption of fruit juices was associated with a higher risk of type 2 diabetes.” However, other studies, including this study of European adults in, incredulously show no link between fruit juice and diabetes risk. But, sadly and invariably, the headline and the lede is all that the mass media market will pick up: Eat more fruit to lower your risk of diabetes. I feel at times like a character in an absurdist plot, “facing the chaos of a world that science and logic have abandoned,” to borrow from a Wikipedia passage describing Theatre of the Absurd.

The absurdity is further confounded by the inherent contradiction of the perfunctory conflicts of interest disclaimer: “The study received funding from the National Institutes of Health. The authors have disclosed no relevant financial relationships.” In other words, fruit growers didn’t pay them to say that “eating more whole fruits...was significantly associated with lower risk of type 2 diabetes.” But the National Institutes of Health did! No conflict of interest there! We taxpayers paid, in part, the costs of this observational report in furtherance of the government’s stated goals, to promote the consumption of “healthy” fruits and vegetables and avoid animal-based nutrition with its attendant “unhealthy” saturated fats and dietary cholesterol.

Since this nuance will be lost on all but the most informed readers, note also that the authors were careful to say that the results were “linked” to the outcomes. The conclusions of all such “studies” show only an association, not a causal relationship, and quite a weak one at that. These confounding factors, including multiple biases assumed, are expressly discussed near the end in the full text of such “studies,” inevitably making the conclusions subjective. In this study, the confounding factors include: “In all three cohorts, total whole fruit consumption was positively correlated with age, physical activity, multivitamin use, total energy intake, fruit juice consumption, and the modified alternate health eating index score, and was inversely associated with body mass index and current smoking.” 

The final paragraph of such full “studies” then invariably acknowledges that the conclusions are inconclusive and require “further study,” preparing the ground in the name of “science” for another grant application to pay the direct salaries and specific expenses of another round of so-called “research.” Call me cynical, if you want, but to me this ongoing charade is phantasmagorical and surreal, if not downright Machiavellian.
Oh, well. At least you can be comforted to know that this “reporter” (your humble blogger) is not paid for his opinions.

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