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THE DIABETIC AT TABLE: OUTCAST OR PARADIGM?
Under the responsibility of Prof. Gérard Slama – Hôtel-Dieu Diabetology Service (Paris)
SUMMARY:
It was not until BOUCHARDAT’S OBSERVATIONS in the 19th century that ‘sugar sickness’ was studied from a dietary perspective through scientific, rigorous and modern investigations, even though it had been known about since ancient times. Massive post-prandial hyperglycosuria, the discovery of impaired glucose tolerance and the resulting interest in restriction of dietary carbohydrates are a few of his own findings that are still deeply rooted in people’s minds.
In the past, a diabetic patient that was placed on a diet had to put up with an illness that received little sympathy from society, being attributed to and considered as a merited outcome of his/her excesses. To this dietary requirement was added the concept of simple sugars which are quickly digested (and prohibited), as opposed to the existence of complex carbohydrates, which are digested slowly and thus better tolerated (and authorized). This improper hodgepodge lead to the emergence of a concept, the glycemic index, that even if not new, at least has a more physiological basis. This index shows that at equal quantities, starchy foods are not interchangeable since some induce more hyperglycemic peaks than others. But there must be agreement upon a reference point, whether from a nutritional (glucose), or a dietary perspective, where bread is chosen due to cultural reasons. The unequivocal conclusion came down to admitting that each food has its own hyperglycemic effect. Nothing is simple, nor fast or slow as far as the finishing line of glycemia “starting blocks” is concerned. The elements involved that shape the outcome compared to glucose are similarities: in chemical structure, in the intestinal pathway for absorption, in the hepatic pathway for biodegradation of molecules that are bound in linear or convoluted spatial configurations according to, in particular the type and degree of cooking in either a solid or liquid environment, or in combination with lipids rather than proteins. Finally, the presence of concomitant fibers and the integration of a carbohydrate load in the meal have an impact on the calculation of a mean glycemic index which is useful in dietetic practice. These characteristics help in placing each carbohydrate at a logical time in the daily diet, rather than having to prohibit or encourage them. A reduction in the quantity consumed and a more spread out consumption of a food with a “high” index reduces the glycemic effect and contributes to the total calorie supply in the form of 45% to 60% of carbohydrate as the energy source which takes into account the initial hypertriglyceridemia. This balancing act allows the outcast to leave the ghetto and join the average Joe in trying to improve their dietary habits and to become a role model.
Frequent and prolonged hyperglycemias are post-prandial in nature. They are eventually responsible, especially if they are of quick onset, for several degenerative vascular complications: microangiopathies (retina, kidney and peripheral nerves) and cardiovascular macroangiopathy. Low-glycemic index foods result in a reduction of plasma LDL-cholesterol as well as triglyceride levels, possibly as a result of a decreased insulin delivery that makes liver biotransformation of carbohydrates and lipids easier. The harmful effect of hyperglycemic peaks of rapid onset does not seem to be associated with leptin. However, the increased levels of free fatty acids may play a role, as suggested by their impact on transcription of genes regulating the PPAR-d, receptors directly implicated in the synthesis of adipose tissues. Here again these discoveries have more relevance in terms of long-term prevention for the healthy subject than for the diabetic subject.
The effects of fructose have been demonstrated to be negligible on lipid and carbohydrate metabolism if consumed in moderate quantities. This finding also applies to sucrose even though a true upper limit of ingestion, while suggested, has not yet been accurately set. Today, there is agreement that 10% of the total energy supply should not have harmful effects on the metabolic health of a diabetic patient as well as on the healthy subject. With regard to polyols and oligofructose-type polymers, their hypotriglyceridemic effects, and to a lesser extent cholesterol-reducing effects, will be reflected in promising studies.
The role of fish oils and free fatty acids, in particular unsaturated omega (W) 3, is well recognized in the prevention of cardiovascular diseases, more particularly coronary heart disease and myocardial infarction, in dyslipidemic patients. This effect is also observed in non-insulin-dependent diabetes mellitus patients (NIDDM) when ingesting these substances at high doses. A marked reduction in triglyceridemia and VLDL levels is observed, with a more variable effect on LDL levels, which are sometimes even increased as observed with HDL2 levels. On the other hand, there is an increase in blood glucose levels in the insulin-dependent diabetes mellitus patient, the reduction in plasma triglyceride levels being obtained to the detriment of blood glucose levels. At a moderate dose (approximately 2 g/d) this drawback does not manifest itself, while the benefit on triglyceride levels is maintained. From this perspective, fish oils when given as supplements are truly comparable to functional foods, which are a protective factor for (micro-)vascular prevention and protection.
Dietary fibers, whose classification and intrinsic properties have been established (see Danone Chair Monograph The Large Intestine in Nutrition and Disease by Prof. John Cummings), may also play a role in carbohydrate and lipid metabolism. In the diabetic patient however, their effects are far from being significant and demonstrated. Short-chain fatty acids, the catabolic derivatives of dietary fibers thanks to the action of the colonic flora, have even more ambivalent effects: acetic acid appears to have no in vivo action, propionic acid may help to reduce fasting blood glucose levels and to improve insulin sensitivity, while the action of other colonic fatty acids is debatable.
The most recent findings, highlighted in this paper are part of a dietary perspective which has been well established elsewhere. It does not seem useful however to review them in detail in a monograph more aimed at the recent discoveries that are useful for balancing the daily diet of diabetic patients.
Conversely, the incorporation of these notions ‘at table”, in the form of practical advice, daily recipes and approaches to cooking, has been the subject of workshops conducted by dieticians. The ideas developed during these sessions conducted in small groups have been brought together in a separate chapter, compiled by one of the participants, a dietician working with children and adolescents suffering from diabetes.
Prof. Slama thus suggests a dietary approach that is less restrictive but no less effective. Rigor is based as much on constant curiosity as on critical thinking which can challenge the most well-established concepts in order to bring out new ideas which are closer to scientific truth, to better meet the demands of the patient without neglecting health requirements.
Language: French
Published in 2003
Edited by the Danone Institute of Belgium
XIII + 98 p.
For more information about this initiative, you can contact the Danone Institute of Belgium
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