Thursday, August 29, 2013

Fast Absorbed High Molecular Weight Resistant Starches Make a Comeback in Diabetic Formula: Are RS-4 (WM-HDP) Based Products An Ideal Meal Replacement for Diabetics?

Pick your metaphor: Clutching to a straw, or hobbling around on a crutch
If type II diabetics were into quasi tube-feeding (=living of meal replacements) or adhering to any diet of some sort, the study Cruz Erika Garcia-Rodriguez and colleagues have recently published in the European Journal of Nutrition could actually be help us solve the to diabesity problem. For me it is  however more of a good reason to take another look at what became of RS-4 (resistant start type 4 = synthetic resistant starches made from waxy maize or tapioca; learn more).

I mean, do we have good reason to mourn, now that Myotropics ThermiCarb(TM) is gone and no legitimate and reasonably prized follow-up product is available?

The stuff still works, but does it also help?

Aside from the fact that I personally consider the idea to feed diabetics liquid foods ludicrous and counter-productive (you do not heal a cripple if you hand him a crouch), the latest results Garcia-Rodriguez et al. present in their paper confirm what we already knew: RS-4 is a non-insulinogenic carbohydrate source that produces
  • higher levels of the incretin hormones ghrelin, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP), and
  • lower levels of insulin and C-peptide compared to iso-energetic "regular carbs" 
at least in the 24 healthy individuals (BMI 23.2kg/m²) who participated in the study at hand. For their type II diabetic counterparts (BMI 35.5kg/m²; HnA1C 8.3%), on the other hand, a significant reduction in postprandial glycemia was the only advantage the researchers could detect.

Diabetic diet formula wars

The actual product the scientists evaluated for their sponsors from Vegenat S.A was albeit not a simple WM-HDP (=waxy maize Hydroxypropyl-Distarch Phosphate) powder.
Table 1: Nutrient composition of formulas used in the study (Garcia-Rodriguez. 2013)
"The tested DSF (T-Diet Plus Diabet NP, Vegenat S.A., Spain) [...] provided 402 kcal/845 kJ (400 ml serving) with 32 g as CHO (40 % of energy), 20.1 g as fat (45 % of energy) and 22 g as protein (15 % of energy) and contained a mixture of vegetable and fish oils (20 mg/dl of eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA)). It also included 7.2 g (20 % on total CHO) of fibre content (inulin and cellulose 20/80 wt/wt). The CHO in this new DSF was low dextrose equivalent (DE) purified and atomized maltodextrins (5–8 DE) (31.7 %) obtained by the hydrolysis of starch, and RS type IV (53.7 %) obtained from partially hydrolysed maize starch by heating in the presence of food grade acid. [...]

The CP [control] was a normoproteic and normocaloric diet which differed to T-Diet Plus Diabet NP in its CHO composition, containing 18–20 DE purified and atomized maltodextrins (99.4 %) obtained by the hydrolysis of starch, and in its fibre content, that is, inulin- and cellulosefree." (Garcia-Rodriguez. 2013)

In contrast to the healthy subjects, on whom the scientists tested only the carbohydrate fraction of this new product the 10 diabetics consumed different commercially available nutritionally complete liquid diet supplements, i.e. T-Diet Plus Diabet NP (Vegenat S.A., Spain), Glucerna SR (Abbott Laboratories, Chicago, IL, USA) and Novasource Diabet (Nestlé Healthcare Nutrition, Switzerland) in 400ml servings after an overnight fast.
Figure 1: Area under the curve (AUC) for biochemical parameters and gastrointestinal hormones in diabetic (left) and healthy volunteers (Garcia-Rodriguez. 2013)
As the data in figure 1 (left) goes to show you, the real-world differences between the products were yet by far less earth-shattering, than you may have expected; and that despite significant differences in their carbohydrate make-up:
  • Glucerna SR contains a complex carbohydrate mixture consisting of fructose (22.9 %) and slowly digestible maltodextrins (49.9 %). It also includes shortchain fructo-oligosaccharides and fibre (6.9 % on total CHO). 
  • Novasource, on the other hand is, based on starch (84 %) and fructose (24 %) as well as fibre (11.7 % on total CHO).
Compared with Glucerna SR and Novasource the product of the study sponsor was also the only one with significant amounts of n-3 fatty acids from plant (linoleic and linolenic acid) and marine sources (EPA+DHA). And still,  as a comparison of the response of the healthy subjects to the same product vs. a regular maltodextrin based formula shows. Neither the lower insulin, c-peptide, triglyceride and GIP levels (all beneficial for weight loss) nor the non-significantly increased GLP-1 levels the scientist observed in the lean individuals were present in the overweight diabetics.

It should be mentioned, though that the control supplement for the healthy individuals was not identical to any of the two formulas that were compared to T-Diet Plus in the experiment with the diabetics. Whether the differences between T-Diet Plus and a "regular" meal replacement would be more pronounced would thus still have to be tested in diabetics.

Certainly no food for diabetics, but as workout fuel for lean athletes RS-4 pancakes could still be useful (more)?
Bottom line: Questionable weight benefit and non-existent anti-diabetic effects - that certainly sounds like any of the commercially available mainstream weight loss products and or meal replacements for diabetics. The significant decrease in blood glucose AUC after the ingestion of the RS4-powered formula, however, could still make a significant health benefit. Just like the crutch that helps you to walk from A to B without straining an already injured ankle even further, RS4 based products could help type II diabetics control their blood glucose levels more than the fructose + regular starch based competition and that would directly reduce the risk of complications!

However, other than real food and lifestyle changes esp. exercise / general physical activity, by the means of which more than half (∼54%) of the patients in the often-quoted Malmö study improved their oral glucose tolerance to an extend that their blood glucose levels were no longer in the critical range (Eriksson. 1999), consuming resistant starches does not have the potential to eradicate diabetes.

References:
  • Eriksson KF, Lindgärde F. Prevention of type 2 (non-insulin-dependent) diabetes mellitus by diet and physical exercise. The 6-year Malmö feasibility study. Diabetologia. 1991 Dec;34(12):891-8.
  • García-Rodríguez CE, Mesa MD, Olza J, Buccianti G, Pérez M, Moreno-Torres R, Pérez de la Cruz A, Gil A. Postprandial glucose, insulin and gastrointestinal hormones in healthy and diabetic subjects fed a fructose-free and resistant starch type IV-enriched enteral formula. Eur J Nutr. 2013 Sep;52(6):1569-78.