The absorption of stearic acid from triacylglycerols: an inquiry and analysis

Abstract

Although stearic acid is a saturated fatty acid, its in¯uence on plasma cholesterol acid other health variables is neutral; possibly owing in part to poor absorption. Reduced absorption of stearic acid from particular triacylglycerols, cocoa butter and novel fats formulated with short-and longchain acid triacylglycerol molecules (Salatrims) has been attributed to high intakes. However, the circumstances and causes of poor stearic acid digestion from triacylglycerols are unclear; published data were therefore collected and analysed, with emphasis on human studies. Of twenty-eight studies conducted in adults, most are in men ( b 90%). The assertion that reduced absorption is due to a high intake of stearoyl groups is not supported: dietary intakes of stearoyl of 0Á05 ±0Á65 g stearic acid equivalent/ kg body weight (cf typical intake of 0Á2 g stearic acid equivalent/kg body weight in the Western diet) indicate that the`true' digestibility of stearoyl is 0Á98 (SE 0Á01) g/g, with apparent digestibility less than this value at low intakes owing to endogenous stearic acid excretion and to inter-publication variation of unidenti®ed cause. The neutral health impact of stearic acid must be due to factors other than availability. Exceptions include cocoa butter, Salatrims and tristearin, for which digestibility is an additional factor. The ef®ciency with which human subjects digest stearoyl from cocoa butter still remains uncertain, while the digestion of total longchain fat from this source is 0Á89± 0Á95 g/g, high in comparison with 0Á33 g/g for Salatrim 23CA and 0Á15 g/g for tristearin in their prepared states. Salatrims contain the highest proportion of long-chain fatty acids that are stearic acid-rich other than tristearin, which is the main component of fully-hydrogenated soyabean and rapeseed oil. Analysis shows that apparent digestibility of stearic acid is associated with stearoyl density within the triacylglycerol molecule and that, in Salatrims, the occurrence of short-chain fatty acids in place of long-chain fatty acids increases this density. Soap formation appears not to be a major factor in the reduced digestion of stearic acid from tristearin under regular dietary circumstances, but both microcrystallinity and reduced digestibility of tri-, diand monostearoylglycerols appears to be important. Solubilisation of high-melting-point tristearin in low-melting-point oils improves the

Health potential of polyols as sugar replacers, with emphasis on low glycaemic properties

“…This corroborates similar findings from elsewhere with men consuming more by weight than women in accordance with higher energy intakes (Glinsmann et al 1986;Henderson et al 2003). In terms of macronutrient exchange or replacement, it is more relevant to consider intakes per meal (rather than per d) because it is the meal that initiates an impulse to which metabolism responds (Livesey, 2000b). For an average three meals per d these sucrose consumption data correspond to an average meal sucrose intake of 8 to 19 g/meal; comparative values for glucose are from 4 to 10 g/meal (Meyer et al 2000).…”

Stearic acid is well absorbed from short- and long-acyl-chain triacylglycerol in an acute test meal

“…It has been suggested that in the mono-and diacetostearines, shortchain acetic acid is favorably hydrolyzed , producing a high melting point and poorly digestible di-and monostearoylglycerols (Livesey, 2000). In the present study, this hypothesis was shown to be untenable.…”

“…It is possible that in Salatrim, the combination of shortand long-chain fatty acids in the same molecule results in only a partial hydrolysis by the pancreatic lipase and a formation of poorly digestible mono-and distearoylglycerols (Livesey, 2000). This could result with partially hydrolyzed Salatrim molecules with esterified stearic acid excreted in the feces.…”

“…It has also been proposed that the reduced availability from Salatrim may result from the high stearic acid density in the triacylglycerol molecule (Livesey, 2000). We investigated the absorption of stearic acid by measuring the fecal fat content after ingestion of a single 30 g dose of Salatrim with a high-fat meal.…”

“…The dominating role of palmitic and stearic acids among the free fatty acids supports the view that once hydrolyzed, saturated long-chain fatty acids more easily remain unabsorbed. A substantial portion of the esterified fatty acids in feces is probably derived from the poorly absorbed trisaturated triacylglycerols of the Salatrim fat (Livesey, 2000).…”