Concentrations of sugars in high-carbohydrate diets

Italian State Railways CP 1011, 35100 Padua Italy E-mail: baschetti{at}shineline.it

Dear Sir:

In Parks and Hellerstein's (1) extensive review article on carbohydrate-induced hypertriacylglycerolemia, there is ample discussion about future research, which probably will be influenced, at least in part, by their excellent article. In view of this probability, to avoid additional misleading studies that cannot be usefully compared (2, 3), it is important to integrate Parks and Hellerstein's data (1) with the recommendation that all future studies on the effects of high-carbohydrate diets should specify whether sugars are consumed in physiologic concentrations <or >4.18 MJ/L. In fact, although sugars in concentrations 4.18 MJ/L leave the stomach progressively more slowly as concentrations increase, thereby allowing energy to be delivered to the intestine at physiologically constant rates per unit of time, sugars in concentrations >4.18 MJ/L leave the stomach more rapidly than do sugars in lower concentrations, thus causing the delivery of unphysiologically high amounts of energy to the intestine per unit of time (4). This recommendation applies especially to studies using liquid-formula diets (5).

Unfortunately, researchers have not yet realized that carbohydrate-induced hypertriacylglycerolemia may simply reflect the unnaturally high concentrations in which sugars are usually ingested and not the effects of a low-fat, high-carbohydrate diet per se (5). When starch accounts for most of the carbohydrates ingested, triacylglycerolemia can be drastically reduced, even in patients with familial endogenous hypertriacylglycerolemia (6).

Considering that the metabolic physiology of our ancestors, who practically lived on fruit for millions of years, was largely molded by the sugars present in fruit (4), which never exceed 4.18 MJ/L, it is hardly surprising that the consumption of sugars in concentrations above this natural limit can result in undesirable consequences (4, 5, 7).

REFERENCES

1. Parks EJ, Hellerstein MK. Carbohydrate-induced hypertriacylglycerolemia: historical perspective and review of biological mechanisms. Am J Clin Nutr 2000;71:412–33.
2. Baschetti R. High-sucrose diets and insulin sensitivity. Am J Clin Nutr 1999;69:575–6 (letter).
3. Baschetti R. Sucrose in weight-loss regimens. Am J Clin Nutr 1998; 67:150–1 (letter).
4. Baschetti R. Sucrose metabolism. N Z Med J 1997;110:43 (letter).
5. Baschetti R. Very-low-fat diets. Circulation 1999;100:1013 (letter).
6. Cominacini L, Zocca I, Garbin U, et al. Long-term effect of a low-fat, high-carbohydrate diet on plasma lipids of patients affected by familial endogenous hypertriglyceridemia. Am J Clin Nutr 1988;48:57–65.
7. Baschetti R. Diabetes epidemic in newly westernized populations: is it due to thrifty genes or to genetically unknown foods? J R Soc Med 1998;91:622–5.