Total, added, and free sugars: are restrictive guidelines science-based or achievable?

Sugar consumption, especially added sugars, is under attack. Various government and health authorities have suggested new sugar recommendations and guidelines as low as 5% of total calories from free sugars. Definitions for total sugars, free sugars, and added sugars are not standardized, nor are there accepted nutrient databases for this information. Our objective was to measure total sugars and added sugars in sample meal plans created by the United States Department of Agriculture (USDA) and the Academy of Nutrition and Dietetics (AND). Utilizing the Nutrition Data System for Research (NDSR) nutritional database, results found that plans created by the USDA and AND averaged 5.1% and 3.1% calories from added sugar, 8.7% and 3.1% from free sugar, and 23.3% and 21.1% as total sugars respectively. Compliance with proposed added sugar recommendations would require strict dietary compliance and may not be sustainable for many Americans. Without an accepted definition and equation for calculating added sugar, added sugar recommendations are arbitrary and may reduce intakes of nutrient-rich, recommended foods, such as yogurt, whole grains, and tart fruits including cranberries, cherries, and grapefruit. Added sugars are one part of excess calorie intake; however, compliance with low added sugar recommendations may not be achievable for the general public.

2-acetyl-4-tetrahydroxybutylimidazole and 4-methylimidazole in caramel colours, vinegar and beverages in China.

A survey of 2-acetyl-4-tetrahydroxybutylimidazole (THI) and 4-methylimidazole (4-MeI) concentrations in caramel colours, vinegar and beverages from the Chinese market were performed by ultrahigh-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). In total, 117 samples, 78 caramel colour samples, 23 vinegar samples and 16 beverage samples, were investigated. The results indicated that 4-MeI was found in all samples. THI was found in a part of the samples and also the level range was lower compared to 4-MeI. In caramel colour samples, the concentration level range of THI was 1.0-74.3 mg/kg and of 4-MeI was 1.5-1291.8 mg/kg. In vinegar samples, the concentration level range of THI was 13.3-119.2 µg/L and for 4-MeI 111.2-2077.8 µg/L. In beverage samples, THI was only found in two samples and the concentration level range of 4-MeI was 10.8-307.1 µg/L. THI and 4-MeI levels in vinegar and beverages were rather low compared with those in caramel colour samples. These observations can be helpful for evaluating individual exposure to THI and 4-MeI from caramel colours, vinegar and beverages in China.

Establishment of the purity values of carbohydrate certified reference materials using quantitative nuclear magnetic resonance and mass balance approach.

This work described the assignment of purity values to six carbohydrate certified reference materials, including glucose, fructose, galactose, lactose, xylose and sucrose, according to the ISO Guides 34 and 35. The CRMs' purity values were assigned based on the weighted average of quantitative nuclear magnetic resonance method and mass balance approach with high resolution liquid chromatography - evaporative light scattering detection. All the six CRMs with following value amount fractions: glucose (GBW10062) at a certified purity P ± U (k=2) of (0.99 ± 0.005)%; fructose (GBW10063) at (0.99 ± 0.005)%; galactose (GBW10064) at (0.99 ± 0.007)%; lactose (GBW10065) at (0.99 ± 0.008)%; xylose (GBW10066) at (0.99 ± 0.007)% and sucrose (GBW10067) at (0.99 ± 0.008)%, respectively were certified. The homogeneity of the CRMs was determined by an in-house validated liquid chromatographic method. Potential degradation during storage was also investigated and a shelf-life based on this value was established.

Evaluation of nondigested carbohydrates in hydroxypropylated tapioca starch.

In vitro and in vivo digestibilities of hydroxypropyl starch were investigated to determine an appropriate nondigested carbohydrate assaying method for hydroxypropyl starch. Hydroxypropyl tapioca starch (HPTS), with a 0.338 degree of substitution, was used as a hydroxypropyl starch source. Practically all nondigested carbohydrate in HPTS was low molecular weight and was not precipitated in 78% ethanol. The contents of nondigested carbohydrate in HPTS and in effluents of ileorectomized rats fed the HPTS diet obtained by the AOAC 2001.03 (enzyme-gravimetric-HPLC method) were almost the same, 56% and 59%, respectively. The recovery of hydroxypropyl groups from ileorectomy effluents was 98%. The AOAC 2001.03 method is suggested to be appropriate in determining the content of nondigested carbohydrates in hydroxypropyl starch.

[Analysis of multi-component sugar aqueous solution in low-concentration by near-infrared spectrometry].

Near infrared spectrophotometry was used to determine the concentrations of one, two and three-component sugar aqueous solutions. However, this method was always applied to dry or low moisture products and was not practicable for fresh fruits and vegetables because of the strong absorption of water in near infrared region. In this paper, the authors applied NIR method to aqueous solutions and discussed how to enhance the sensitivity. In aqueous solution systems, concentration of each individual sugar was in range of 0.01-0.25 mol x L(-1). Different calibrations and predicted results were gotten and compared to each other when full spectra or significant spectra regions were considered. By selecting relevant spectra regions due to important structural information to overcome the disturbance from absorption of water, calculations could be optimized and predicted results of concentrations were more accurate regarding the standard error of calibration (SEC) and standard error of prediction (SEP).

Comparison of methods for transfer of calibration models in near-infared spectroscopy: a case study based on correcting path length differences using fiber-optic transmittance probes in in-line near-infrared spectroscopy.

This article addresses problems related to transfer of calibration models due to variations in distance between the transmittance fiber-optic probes. The data have been generated using a mixture design and measured at five different probe distances. A number of techniques reported in the literature have been compared. These include multiplicative scatter correction (MSC), path length correction (PLC), finite impulse response (FIR), orthogonal signal correction (OSC), piecewise direct standardization (PDS), and robust calibration. The quality of the predictions was expressed in terms of root mean square error of prediction (RMSEP). Robust calibration gave good calibration transfer results, while the other methods did not give acceptable results.

Plasma glucose turnover and oxidation during hemodialysis: nutritional effect of dialysis fluid.

Mass transfer of glucose from dialysis fluid into patients is a source of energy and a form of nutrition during hemodialysis. The effect of glucose mass transfer on endogenous glucose metabolism and the overall nutritional importance of glucose transfer is not known. Rates of plasma glucose turnover and oxidation were determined by radioisotope-dilution techniques in patients with chronic renal failure (CRF) in the basal state, during hemodialysis, and during the infusion of glucose at a rate similar to the mass transfer rate (Mt: 6.6 +/- 0.7 mumol.min-1.kg-1). Rates of plasma glucose turnover (11.8 +/- 0.8 mumol.min-1.kg-1) and oxidation (4.0 +/- 0.4 mumol.min-1.kg-1) and contribution of glucose oxidation to the metabolic rate were similar to those of control subjects both in the basal state and during glucose infusion. During hemodialysis with acetate and glucose, the plasma glucose turnover rate was similar to that in the basal state, but the energy from glucose oxidation was less (P < or = 0.02) even though energy expenditure was increased by 21%. Immediate oxidation of plasma glucose and acetate accounted for 65% of the patients' energy expenditure. Energy (1172 kJ) from acetate Mt and glucose Mt surpassed the patients' energy requirements, offsetting the utilization of endogenous fuels, a sparing effect equivalent to 31 g fat or 70 g carbohydrate. Rates of plasma glucose turnover and oxidation during bicarbonate-glucose and glucose-free acetate hemodialysis were similar to that during acetate-glucose hemodialysis. However, without glucose or acetate in the bath fluid, a deficit as much as 669 kJ must be met by the oxidation of endogenous fuels. Addition of organic nutrients that supply energy to dialysis fluids may over time be a beneficial supplemental treatment for the malnutrition and body wasting commonly observed in CRF.

Randomized clinical trial of nutritional supplementation shows little effect on functional status among free-living frail elderly.

Nutritional deficiencies, frequently observed among the frail elderly, have been associated with increased morbidity and dependency. A randomized clinical trial was conducted to assess the impact of nutritional supplementation on the functional status of frail elderly living at home. Subjects (n = 50) over age 60 (mean 78 y) requiring community services and at elevated risk of undernutrition (excessive weight loss or body mass index < 24 kg/m2) were randomized to a high energy nutrient dense supplement provided by a dietitian or a control group receiving visits only. Outcome measures, including changes in handgrip strength, general well-being score, perception of health and number of falls, were measured by an investigator who was unaware of treatment assignment. After 12 wk, weight gain was greater in the supplemented group (2.1 +/- 2.3 vs. 0.6 +/- 1.6 kg; P < 0.01). Despite adequate statistical power, no functional measures differed except that the number of falls was lower among treated subjects vs. controls (0% vs. 21%; P = 0.05). Frail elderly can gain weight through oral supplementation, indicating the reversibility of weight loss in this group, but changes in functional status indicators may require a longer period of supplementation.

Determination of the carbohydrate composition of mammalian glycoproteins by capillary gas chromatography/mass spectrometry.

A technique to determine the carbohydrate composition of glycoproteins using capillary gas chromatography/mass spectrometry (electron impact) with selected ion monitoring is described. This method entails hydrolysis with methanolic-HCl followed by formation of trimethylsilyl methylglycoside derivatives, extraction of the carbohydrate derivatives into hexane, and GC/MS analysis. For those carbohydrates that are present in animal glycoproteins including fucose, mannose, galactose, glucosamine, galactosamine, and N-acetylneuraminic acid (sialic acid), the sensitivity of this assay was approximately 1-3 pmol and the assay was linear over a 100-fold range. The carbohydrate compositions determined on small quantities (1-10 pmol) of various glycoproteins including human transferrin and alpha-1 acid glycoprotein, fetuin, and ovalbumin were identical to their reported carbohydrate content and compositions. Major advantages of this technique include the time required to complete the sample preparation and analysis (less than 8 h), the sensitivity and specificity of the assay, and the fact that all carbohydrate moieties, including sialic acid, can be quantitated in a single hydrolysate of a glycoprotein.