Summary  Resistant starch (RS) refers to the portion of starch and starch products that resist digestion as they pass through the gastrointestinal tract. RS is an extremely broad and diverse range of materials and a number of different types exist (RS1–4). At present, these are mostly defined according to physical and chemical characteristics. RS may be categorised as a type of dietary fibre, as defined by the American Association of Cereal Chemists and the Food Nutrition Board of the Institute of Medicine of the National Academies. RS is measured in part by the methodology recommended by the Association of Official Analytical Chemists for measuring dietary fibre. Dietary intakes of RS in westernised countries are likely to be low. However, accurate comparative assessments of dietary intakes between countries, and subsequent epidemiological analysis, are absent due to the lack of consensus over of an agreed, repeatable and simple in vitro method for analysing the RS content of foods. At present, the recognised method is that of McCleary & Monaghan (2002). RS appears to confer considerable benefits to human colonic health, but has a smaller impact on lipid and glucose metabolism. Comparisons between studies are hampered by differences in study design, poor experimental design and differences in the source, type and dose of RS in the ingredients or diets used. It is likely that RS mediates some or all of its effects through the action of short chain fatty acids but interest is increasing regarding its prebiotic potential. There is also increasing interest in using RS to lower the energy value and available carbohydrate content of foods. RS can also be used to enhance the fibre content of foods and is under investigation regarding its potential to accelerate the onset of satiation and to lower the glycaemic response. Due to the difficulties in agreeing on a universal definition and method of analysis for dietary fibre, RS may be included within the term ‘fibre’ on the nutrition labels in some countries but not in others. Pressure to agree a legal definition and universal method of analysis is likely to increase due to the potential of RS to enhance colonic health, and to act as a vehicle to increase the total dietary fibre content of foodstuffs, particularly those which are low in energy and/or in total carbohydrate content.

The merits of a fibre-rich diet are well documented. Resistant starch (RS) is a form of starch that resists digestion in the small intestine and, as such, is classified as a type of dietary fibre. RS can be categorised as one of five types (RS1-5), some of which occur naturally in foods such as bananas, potatoes, grains and legumes and some of which are produced or modified commercially, and incorporated into food products. This review describes human evidence on the health effects of RS consumption, with the aim of identifying any benefits of RS-rich foods and RS as a functional ingredient. The reduced glycaemic response consistently reported with RS consumption, when compared with digestible carbohydrate, has resulted in an approved European Union health claim. Thus, RS-rich foods may be particularly useful for managing diabetes. There appears to be little impact of RS on other metabolic markers, such as blood pressure and plasma lipids, though data are comparatively limited. Promising results on markers of gut health suggest that further research may lead to the classification of RS as a prebiotic. Microbial fermentation of RS in the large intestine to produce short-chain fatty acids likely underpins some of its biological effects, including increasing satiety. However, effects on appetite have not resulted in notable changes in bodyweight after long-term consumption. Emerging research suggests potential for RS as an ingredient in oral rehydration solutions and in the treatment of chronic kidney disease. Overall, RS possesses positive properties as a healthy food component.

Conjugated linoleic acid (CLA) refers to a group of positional and geometric isomers of linoleic acid. Studies using animal models have shown that CLA reduces adiposity, improves plasma lipoprotein metabolism and insulin sensitivity and reduces arteriosclerosis. Whilst CLA may have therapeutic potential with regard to coronary artery disease risk factors in human subjects, there has been little investigation into its effects in human subjects. This current study investigated the effects of dietary supplementation using two isomeric blends of CLA on triacylglycerol (TAG)-rich lipoprotein metabolism and reverse cholesterol transport in human subjects and evaluates whether CLA modulated cardiovascular disease risk factors. Fifty-one normolipidaemic subjects participated in this randomised double-blind placebo-controlled intervention trial. Subjects were randomly assigned to receive 3 g cis-9,trans-11 -trans-10,cis-12 isomeric blend (50 : 50) or a cis-9,trans-11-trans-10,cis-12 isomeric blend (80 : 20) CLA or linoleic acid (control)/d for 8 weeks. The 50 : 50 CLA isomer blend significantly reduced (P# 0·005) fasting plasma TAG concentrations. The 80 : 20 CLA isomer blend significantly reduced (P# 0·05) VLDL-cholesterol concentrations. CLA supplementation had no significant effect on LDL-cholesterol, HDL-lipid-protein composition or reverse cholesterol transport. CLA supplementation had no effect on body weight, plasma glucose and insulin concentrations. Fatty acid analysis revealed that the cis-9,trans-11 CLA isomer was incorporated into total plasma lipids following supplementation with both isomeric blends of CLA. The present study demonstrates that CLA supplementation significantly improves plasma TAG and VLDL metabolism in human subjects. The study confirms that some of the cardio-protective effects of CLA that were shown in animal studies are relevant to man.Conjugated linoleic acid: Triacylglycerol: Very-low-density lipoprotein: Low-density lipoprotein: High-density lipoprotein Conjugated linoleic acid (CLA) is the term used to describe a mixture of positional and geometric isomers of linoleic acid, with conjugated double bonds, which may be of cis or trans configuration at positions 9 and 11 or 10 and 12 (Ha et al. 1987). CLA is a natural food constituent, produced by the intestinal flora of ruminant animals (Kepler et al. 1970) and is found in the lipid fraction of meat and dairy products. Chin et al. (1992) estimated the daily intake of CLA in human subjects to be 160 mg/d. Several animal studies have established that CLA has profound effects on lipoprotein metabolism and prevents dietinduced atherosclerosis. Lee et al. (1994) showed that CLA significantly reduced plasma triacylglycerol (TAG) and LDL-cholesterol concentrations and demonstrated that cholesterol deposition in the aorta was 30 % less in the CLA-fed rabbits. Nicolosi et al. (1997) demonstrated that CLA supplementation significantly reduced plasma TAG (2 28 %) and cholesterol (2 26 %) concentrations, which were associated with a significant redu...

should be used to assess vitamin D status, as it reflects combined dietary supply and dermal production upon exposure to UV blue (UVB) sunlight (2) . Notwithstanding the importance of on-going discussions with respect to thresholds for serum 25(OH)D that represent adequacy/insufficiency, there is widespread acknowledgement of the presence of vitamin D deficiency in the community and the pressing need to address this deficiency (3) .Taking indicators of bone health, including rickets and osteomalacia, bone mineral density and Ca absorption, for which there was sufficient evidence to provide a reasonable and supportable basis for dietary reference intake (DRI) development, the North American Institute of Medicine (IOM)'s DRI committee for Ca and vitamin D proposed a serum 25(OH)D concentration of 40 nmol/l as the median value above which approximately half the population might meet its vitamin D requirement (and below which half might not) and 50 nmol/l as its estimate of the serum 25(OH)D concentration that would meet the requirement of nearly all (i.e. 97·5 %) normal healthy persons (4) . These serum 25(OH)D concentrations were used to specify estimated average requirement (EAR) values for vitamin D intakes of 400 IU/d (10·0 mg/d) in all age and sex subgroups in the population for more than 1 year, assuming minimal UVB sunlight exposure, and from which RDA values were derived for application to individuals (600 and 800 IU/d (15·0 and 20·0 mg/d) of vitamin D for those aged 1 -70 and 70þ

Adipose tissue may be the source of insulin desensitizing proinflammatory molecules that predispose to insulin resistance. This study investigated whether dietary fatty acids could attenuate the proinflammatory insulin-resistant state in obese adipose tissue. The potential antidiabetic effect of cis-9, trans-11-conjugated linoleic acid (c9,t11-CLA) was determined, focusing on the molecular markers of insulin sensitivity and inflammation in adipose tissue of ob/ob C57BL-6 mice. Feeding a c9,t11-CLA-enriched diet reduced fasting glucose (P < 0.05), insulin (P < 0.05), and triacylglycerol concentrations (P < 0.01) and increased adipose tissue plasma membrane GLUT4 (P < 0.05) and insulin receptor (P < 0.05) expression compared with the control linoleic acid-enriched diet. Interestingly, after the c9,t11-CLA diet, adipose tissue macrophage infiltration was less, with marked downregulation of several inflammatory markers in adipose tissue, including reduced tumor necrosis factor-alpha and CD68 mRNA (P < 0.05), nuclear factor-kappaB (NF-kappaB) p65 expression (P < 0.01), NF-kappaB DNA binding (P < 0.01), and NF-kappaB p65, p50, c-Rel, p52, and RelB transcriptional activity (P < 0.01). To define whether these observations were direct effects of the nutrient intervention, complimentary cell culture studies showed that c9,t11-CLA inhibited tumor necrosis factor-alpha-induced downregulation of insulin receptor substrate 1 and GLUT4 mRNA expression and promoted insulin-stimulated glucose transport in 3T3-L1 adipocytes compared with linoleic acid. This study suggests that altering fatty acid composition may attenuate the proinflammatory state in adipose tissue that predisposes to obesity-induced insulin resistance.