Thursday, December 4, 2014

Planning to Have a Pizza? Preload w/ Navy Beans, Chickpea or Lentils to Ameliorate Your Glucose Response. Plus: Are the Changes Even Physiologically Relevant?

I am pretty sure that putting means onto your pizza will also work, but probably only due to replacing unhealthier stuff ;-)
It sounds funny, but eating a 188g of canned, well-chewed navy beans, 62.5g whole navy bean powder, 184g of whole canned green or their pureed counter-part, or simply chewing down 48g of Eston lentil powder or 148.8g of canned or pureed chickpeas will ameliorate the glucose response to a standardized pizza meal.

Speaking of which: The nutritional composition of the pulse treatments and control is listed in Table 1. All treatments and control were of similar available carbohydrate content (38·8 g), with 25 g from the test ingredient (pulses or whole-wheat flour) and 13·8 g from the tomato sauce.
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The pulse treatments and control were prepared the day before each session, transferred to airtight containers, combined with water to reach a final weight of 405·0 g, and sealed in airtight containers for overnight storage in an experimental fridge.
Table 1: Nutritional composition of the "preloads" (Anderson. 2014)
To prepare the whole-pulse treatments, canned navy beans (Expt 1), lentils (Expt 2) and chickpeas (Expt 3) were poured into a strainer, washed thoroughly under running water for 30 s and drained well. Pulses were then combined with filtered water while the tomato sauce ingredients were cooked in a non-sticky pan on medium heat (3 min).
But beans are bad for my health, aren't they? From a psychological perspective, you may be right. In view of the fact that people really feel sick, when they've read about the (non-existent) ill health of effects of certain foods on the Internet. Some of you may actually become sick ;-)

Mechanism by which beans reduce your hyperlipidemia, diabetes and cancer risk (Hayat. 2014).
Aside from the fact that starting eating tons of beans from one day to the other may overload your digestive tract and make you "socially incompatible" (due to flatulence), the overwhelming majority of scientific studies indicates that an increased consumption of Beans (Phaseolus vulgaris L.) will not just improve your supply of nutrients such as multifaceted carbohydrates, proteins, dietary fiber, minerals, and vitamins, but also exert direct health benefits due to their rich variety of polyphenolic compounds with (Hayat. 2014). These benefits range from a general improvement of your antioxidant defense system over reductions in cardiovascular disease risk and improvements of your lipid and glucose metabolism to a reduced cancer risk.
In order to make them palatable, the pulses were mixed with tomato sauce, garlic and herbs, dried basil leaves, ground black pepper, garlic powder, dried parsley flakes, and the typical American way with added sugar (1.2 ml).
The subjects, young men, aged 18-25 years old with a normal BMI reported at the lab following a 10–12 h overnight fast, participants were instructed to consume a standardised breakfast (1422.6 kJ) in the morning within 15 min and arrive at the laboratory 4 h later.
"The standardized breakfast was provided to them in advance and consisted of 26 g of Honey Nut Cheerios cereal (General Mills), 250 ml of Beatrice 2 % milk (Parmalat Canada) and 250 ml of Tropicana orange juice (Tropicana Products, Inc.). In addition, 500 ml of bottled water (Canadian Springs) were included, and participants were required to finish the bottle by 1 h before the session start time." (Anderson. 2014)
Upon arrival, participants were asked to complete a Sleep Habits and Stress Factors Questionnaire and an Activity Questionnaire. If they reported significant deviations from their usual patterns, they were asked to reschedule. Baseline blood samples were obtained by finger prick by a Monojector Lancet Device (Sherwood Medical), and the blood glucose (BG) concentrations were measured by using a glucose meter (Accu-Chek Compact Plus Glucose Monitor; Roche Diagnostics Canada).

What exactly did the scientists do with the "preloads"?

After taking baseline measurements for BG, participants were given 15 min to consume either one of the treatments or control provided to them in random order with 250 ml of filtered water. BG concentration was measured at 15, 30, 45, 60, 90 and 120 min. At 120 min, participants were asked to consume a fixed-size pizza meal (50·2 kJ/kg body weight, McCain Deep ‘N Delicious; McCain Foods Limited) with 500 ml of filtered water (which could be consumed ad libitum) within 20min in order to measure post-second-meal glycaemic response without the variation introduced by ad libitum food intake. The pizzas averaged 7·6 g protein, 4·9 g fat, 29·3 g carbohydrate and 818·6 kJ/100 g. Each cooked pizza (8 min at 227 8C and cut in quarters) was weighed before serving. Following the pizza meal, BG concentration was measured repeatedly at 140, 155, 170, 185 and 200 min.
Figure 1: Effect of the treatments on absolute blood glucose concentration over time. (A) Expt 1, (B) Expt 2 and (C) Expt 3. Values are means (n 17 in Expt 1, n 12 in Expt 2 and n 12 in Expt 3), with their standard errors represented by vertical bars (Anderson. 2014).
As you can see in Figure 1, the improvements were not exactly earth-shattering. Against that background it is questionable, whether the overall lower glycaemic response will be of practical relevance.
Navy beans are also a good source of fermentable starches (10g per 1/2 cup) and could thus have longer lasting beneficial effects by eventually ramping up your short-chain fatty acid production and thus promoting longterm fat loss, improved gut health and cancer protection | learn more about these and other benefits of fermentable starches!
So what's the important finding, then? In view of the modest reductions in glycemia, the most important finding of the study probably isn't the overall reduction in glycemia, which has been observed in previous studies, already. Rather than that, it is the fact that the pureed and, even more surprisingly, the powdered premeals had the same effect as the fresh whole beans, lentils and chickpea.

Or, as the scientists write the fact that "commercial processing of pulses to a powder form does not alter their low glycaemic characteristics" (Anderson. 2014). Accordingly, pulse powders can be used as "value-added ingredients in home cooking and functional foods to improve postprandial glycaemic control" (Anderson. 2014) - more specifically this could be a way to add pulses to convenience foods and thus have those individuals who normally avoid them due to taste or perceived inconvenience benefit from the improved glycemia | Comment on FB!
References:
  • Anderson, G. Harvey, et al. "The acute effect of commercially available pulse powders on postprandial glycaemic response in healthy young men." British Journal of Nutrition (2014): 1-8. 
  • Hayat, Imran, et al. "Nutritional and health perspectives of beans (Phaseolus vulgaris L.): An Overview." Critical reviews in food science and nutrition 54.5 (2014): 580-592.