The typical dietary supply of total fat, fatty acids, starch, sugars, polyols and dietary fibre in Sweden was assessed from analyses of market baskets (MB) purchased in 2005 and 2010. MB were based on food balance sheets, with each basket comprising about 130 foods, which represented more than 90 % of annual dietary supply. Foods were divided into ten to twelve categories. In 2010, total fat contributed 34 % of energy (E%), SFA 14·3 E%, MUFA 12·8 E%, PUFA 4·6 E%, n-6 fatty acids 3·6 E%, n-3 fatty acids 1·0 E% and trans-fatty acids (TFA) 0·5 E%. Glycaemic carbohydrates contributed 47 E%, monosaccharides 9 E%, sucrose 11 E%, disaccharides 15 E% and total sugars 24 E%. Added sugars contributed about 15 E%. Dietary fibre content was about 1·7 g/MJ in the 2010 MB. Compared with the 2005 MB, the dietary supply of TFA and dietary fibre was lower, otherwise differences were small. The present MB survey shows that the content of SFA and added sugars was higher than the current Nordic Nutrition Recommendations, while the content of PUFA and especially dietary fibre was lower. TFA levels decreased and dietary supply was well below the recommendations of the WHO. These results emphasise a focus on quality and food sources of fat and carbohydrates, limiting foods rich in SFA and added sugars and replacing them with foods rich in dietary fibre and cis-unsaturated fatty acids.

During a 7-day conditioning treatment of clumps of oil palm (Elaeis guineensis Jacq.) somatic embryos on a medium containing 0.75 M sucrose, the fructose and glucose concentrations remained constant, whereas a ten-fold and twenty-fold increase were noted for sucrose and starch concentrations, respectively. The only new sugar detected was arabinose which remained at a low concentration. After conditioning on media supplemented with various sugars and polyols at similar osmolarities, recovery of clumps of embryo growth was satisfactory except with ribose. After an additional desiccation period, survival was optimal with fructose, galactose, sucrose and glucose, intermediate with maltose and lower with other compounds. When embryos were cryopreserved without previous desiccation, survival was noted after conditioning treatment with sucrose only. In contrast, when freezing was performed after dehydration, survival could be obtained with several substances. It was optimal with sucrose, fructose, galactose and raffinose but was possible also with sorbitol and glucose. Intensity of recovery of proliferation was highest with embryos conditioned with sucrose.

Ethanol extractable polyols and sugars from the dominant cryptogams of the Windmill Islands, Wilkes Land, East Antarctica, were characterized and quantified by gas liquid chromatography. Arabitol, ribitol and mannitol were the major low molecular weight carbohydrates extracted from all eight species of lichen analysed. Total extractable carbohydrate levels (20–60 mg g−1 dry weight) were comparable to those for temperate lichens. Extracts of four common bryophyte species were dominated by sucrose, glucose and fructose; little polyhydric alcohol was detected except in the liverwort Cephaloziella exiliflora which contained a substantial proportion of mannitol. Total carbohydrate levels in the bryophytes (9–60 mg g−1 dry weight) were comparable to those in lichens. The compositions of eight species of algae varied considerably. Prasiola crispa, Desmococcus vulgaris and Schizogonium murale possessed sorbitol as their main constituent and had extractable carbohydrate contents comparable to those found in bryophytes on a dry weight or chlorophyll a content basis. The one snow alga with comparable carbohydrate levels, Mesotaenium berggrenii, contained sucrose, glucose, glycerol and a number of unidentified compounds. The remaining four species (Oscillatoria sp., Chloromonas sp.1 and Chlorosarcina sp. 2 and Chlamydomonas pseudopulsatilla) did not accumulate comparable levels of sugars and polyols. Though the levels of these compounds were much lower in the Windmill Islands lichens than in maritime Antarctic species, their content with respect to water content (0.7–7 molal) was well above that at which cold acclimated plants accumulate these compounds (c. 100–500 millimolal), and which provide cryoprotection in vitro. In the case of the bryophytes and algae, however, the in vivo content was generally < 100 millimolal.

Levels of polyhydric alcohols and oligosaccharides in the lichens Umbilicaria decussata and Usnea sphacelata were measured in samples obtained from unpolluted and polluted sites on Bailey Peninsula, Windmill Islands, Budd Coast. Undisturbed lichen possessed levels of these compounds (33 and 20 mg g-1 dry weight respectively) typical of those found in lichens from temperate climates. Plants from sites severely polluted by alkaline cement dust, derived from concrete mixing activities, possessed significantly lower levels (P < 0.01) of these intracellular constituents. Levels of chlorophyll a in Umbilicaria decussata were significantly correlated with total polyols + sugars (r2 = 0.88). We suggest that environmental impacts on Antarctic vegetation may be measured by parallel determinations of these two parameters on sensitive lichen species such as Umbilicaria decussata.

In the cold Antarctic environment labile organic compounds may accumulate in soil due to relatively low utilization rates by heterotrophic microorganisms. Microbial fermentation of these compounds might contribute to the development of strongly acid soils. To test this and assess concentrations, extracts of a range of soils in the Windmill Islands, Budd Coast were analysed by GLC and HPLC for the presence of low molecular weight sugars, polyols and organic acids. Concentrations of sugars and polyols up to 3300 mg g−1 were detected in cryptogam dominated soils. Some, such as trehalose, may have principally originated in the soil microflora. Soils from occupied penguin rookeries were found to possess oxalic, acetic, propionic and succinic acids at levels up to 1000 mg g−1 soil. Most other soils, however, lacked these acids at detectable levels (1–5 mg g−1 soil). No correlation was established between organic acid accumulation and soil pH although those dominated by moss and lichen had been acidified significantly when compared with barren soils. Thus while substantial pools of these readily utilized carbohydrates were probably present in cryptogam dominated soils, there was little accumulation of organic acids which could account for the acidity of mineral soils typical of the Windmill Islands.

Water soluble compounds were extracted from the dominant cryptogams of the Windmill Islands, Wilkes Land, and compared with standard polyols, sugars and amino acids using 13C nuclear magnetic resonance (NMR) spectroscopy. Previous findings for sugars and polyols from gas liquid chromatorgraphy were validated and extended. Arabitol, ribitol and mannitol were confirmed as the major soluble carbohydrate compounds in all lichen species examined. Sucrose, fructose and glucose, but no polyols were detected in two species of moss. Sorbitol was confirmed as a major component of the algae Prasiola crispa and Schizogonium murale. Mesotaenium bergrenii was confirmed to contain sucrose and glucose. No significant quantities of sugars or polyols or any other compound were found in extracts of the red snow alga Chloromonas sp.1. Amino acids were detected in the majority of cryptogam samples and were particularly abundant in the algae P. crispa and S. murale. In the latter species the total identified acids ranged from 13.5–66mg g-1 dry weight. In addition to the common amino acid components of proteins, betaine and γ-amino-butyric acid were detected, the latter being particularly abundant, being found widely in the moss, lichen and algae. Several unknown carbohydrates were characterized. Usnea sphacelata, U. antarctica and Pseudephebe minuscula contained a deoxy-hexitol, Grimmia antarctici contained resonance peaks consistent with a trisaccharide containing a sucrose moiety and Umbilicaria decussata possibly contained a glucose-arabitol dimer. 13C NMR was confirmed as a powerful tool for the characterization of low molecular weight constituents of Antarctic cryptogams.

The metabolizable energy content of low-digestible carbohydrates does not correspond with their true energy value. The aim of the present study was to determine the tolerance and effects of two polyols on digestion and energy expenditure in healthy men, as well as their digestible, metabolizable and net energy values. Nine healthy men were fed for 32 d periods a maintenance diet supplemented either with dextrose, Lycasin®HBC (Roquette Frères, Lestrem, France), or the hydrogenated polysaccharide fraction of Lycasin®HBC, at a level of 100 g DM/d in six equal doses per d according to a 3×3 Latin square design with three repetitions. After a 20 d progressive adaptation period, food intake was determined for 12 d using the duplicate meal method and faeces and urine were collected for 10 d for further analyses. Subjects spent 36 h in one of two open-circuit whole-body calorimeters with measurements during the last 24 h. Ingestion of the polyols did not cause severe digestive disorders, except excessive gas emission, and flatulence and gurgling in some subjects. The polyols induced significant increases in wet (+45 and +66 % respectively, P<0·01) and dry (+53 and +75 % respectively, P<0·002) stool weight, resulting in a 2 % decrease in dietary energy digestibility (P<0·001). They resulted also in significant increases in sleeping (+4·1 %, P<0·03) and daily energy expenditure (+2·7 and +2·9 % respectively, P<0·02) compared with dextrose ingestion. The apparent energy digestibility of the two polyols was 0·82 and 0·79 respectively, their metabolizable energy value averaged 14·1 kJ/g DM, and their net energy value averaged 10·8 kJ/g DM, that is, 35 % less than those of sucrose and starch.

Low-digestible carbohydrates (LDCs) are incompletely or not absorbed in the small bowel and fermented in the colon. They are usually well tolerated but may also have some dose-related undesirable effects due to their natural osmotic potential and/or excessive fermentation: borborygmi, excessive flatus, bloating, abdominal cramps and eventually diarrhoea. There is an important intersubject variability in the tolerance to LDCs because of differences in absorption capacity, motility pattern, colonic response and intestinal sensitivity. There is also a great intrasubject variability, depending on the type of LDC, dosage and type of consumption. Absorption of LDC in the small intestine can be assessed using hydrogen breath test or intubation techniques or analysis of ileostomy effluents. Double-blind, placebo-controlled studies are required to assess the subjective symptoms of intolerance, and the experimental conditions may influence the results.

Polyol-containing confectionery offers considerable advantages over traditional sucrose-based confectionery in terms of reduced energy content and reduced cariogenicity. However, over-consumption of polyol confectionery may lead to gastrointestinal symptoms in some individuals. Rather than consider this as a distinct disadvantage to the consumer, this article discusses how careful consideration of the physico-chemical properties of polyols and advances in product development and formulation can provide suitable polyol-based products for the consumer. Furthermore, food legislation and ingredient pricing issues are just some of the factors that must be taken into account when designing new polyol-containing products if their functional benefits and good product quality are to be delivered to the consumer.

Legislation is described that impacts on the use of low-digestible carbohydrates in foods. This includes controls on the use of these carbohydrates, mandatory labelling concerned with gastrointestinal effects, nutrition labelling, and nutrition and other claims. Regional differences in approach to legislation have led to inconsistencies in the information that must be provided to consumers, even for the same food products. Also, within regions, different regulations apply to food carbohydrates that may be classified similarly from the physiological perspective. Consistency of food labelling globally and in application to similar carbohydrates would benefit from greater attention to the underpinning science.

The tolerance of low-digestible carbohydrates (LDCs) may be measured as the potential to cause abdominal symptoms and laxation. Tolerance of any one LDC is determined by its concentration in the food product eaten, the amount of the food product eaten, the frequency of eating the food and the consumption of other foods (increasing tolerance) and water (decreasing tolerance). Added to these, individuals vary considerably in their response to low-digestible carbohydrates in the reporting of gastrointestinal symptoms. A precise maximum no-response dose is sometimes difficult to obtain because some dose–response curves are distinctly sigmoidal. Food regulators hoping to set a trigger level at which laxation may occur have been unable to take account of all these factors because the necessary information matrices are not available for any one LDC. Nevertheless analysis of the data shows consistent trends and for circumstances when food is consumed throughout the day it now seems feasible to assign specific tolerances to specific low-digestible carbohydrates, especially the polyols for which most is known. The method by which the no-effect dose or laxative threshold is expressed is critical to its application to individual foods.

The unicellular, acido- and thermophilic red alga Galdieria sulphuraria is unique in its ability to grow heterotrophically on at least 27 different sugars and polyols. The enzymatic machinery necessary for metabolizing this variety of compounds is constitutively expressed in the alga. The uptake system, however, has to be induced. From in vivo studies we conclude that the uptake system consists of several transporters with a partly overlapping substrate specificity. These transporters can be grouped into hexose, polyol and pentose transporters. The mode of induction depends on the substrate supplied for heterotrophic growth. When autotrophic cells were supplied with hexoses, hexose and polyol transporters were induced from the onset of heterotrophic conditions. Depletion of substrate in the medium triggered the induction of other transporters. Dulcitol, as well as other polyols and pentoses, led to a co-induction of all transporters as judged from induction and competition experiments. The heterotrophic capabilities of Galdieria are intriguing, because the natural habitat of the alga contains only traces of organic carbon. The substrates for heterotrophic growth apparently originate from decaying cells releasing hydrolysed cell material. Trace amounts of glucose were sufficient for the induction of sugar uptake in Galdieria. The co-induction of transporters obviously enables the cells in endolithic mats to import a wide spectrum of organic carbon in order to survive periods of light limitation.