Rheumatoid arthritis (RA) is characterised by chronic inflammation in joints. Obesity, stress, being women and dietary pattern are important in pathogenesis. The joint damage in RA is accelerated by oxidative stress. The aim of this study was to examine the serum total antioxidant level, nutritional status and Mediterranean diet adherence of adult women with RA. Thirty-five adult women RA patients and thirty-five healthy control participated in this study (45·4 ± 11·61 and 42·5 ± 8·50 years, respectively). Nutritional status, physical activity levels and adherence to the Mediterranean diet were questioned. Physicians assessed the disease activity score of patients with RA. Serum total antioxidant and oxidant status were analysed. The serum total antioxidant status of the control group was higher, whereas the oxidative stress index and total oxidant status were lower than that of the RA group. Dietary protein, fibre, EPA, retinol, Fe, Zn and total antioxidant intake in the RA group were lower than in the control group (P < 0·05). Individuals with higher fibre intake showed a significantly lower risk for RA after adjusting for potential confounding factors (OR = 0·845, 95 % CI = 0·773–0·923, P < 0·001). The mean physical activity level of the control group was higher than that of the RA group (1·59 ± 0·10 and 1·53 ± 0·13, respectively) (P = 0·01). In conclusion, serum antioxidant parameters and dietary antioxidant intake are decreased in patients with RA. Therefore, medical treatment for these patients should be supplemented with medical nutrition therapy to achieve optimal nutritional status.

The present prospective cohort study aimed to determine whether dietary antioxidants were associated with incident type 2 diabetes mellitus (T2DM). Another objective was to find out whether such associations could be modified by the BMI status. A total of 2188 Tehranian adults aged 21–84 years, free of T2DM with the validated FFQ, was entered in the study. Multivariable Cox proportional hazards models adjusting for confounders were used to assess the association between dietary antioxidants and incident T2DM in total population, as well as in subjects with various BMI statuses. During 8·9 (8·1–9·6) years of follow-up, dietary vitamin E significantly decreased the incident T2DM, after adjustment for confounders. However, other dietary antioxidants were not shown to be significantly associated with incident T2DM. The interaction between dietary vitamin E, Mg and BMI status was found to influence the risk of T2DM (Pfor interaction < 0·05). After stratification of subjects based on BMI status, it was found that vitamin E and Mg decreased the risk of T2DM only among normal-weight individual. Also, an inverse association was found among dietary vitamin C, dietary Zn and the risk of T2DM in individuals with normal weight but not in overweight and obese individuals; however, the interaction test tended to be significant for these dietary variables. Dietary antioxidants including vitamin E, vitamin C, Zn and Mg when accompanied by healthy weight, may bring benefits to the prevention of T2DM.

The objective of the present study was to determine the inhibitory effect of dietary rosemary diterpenes on the formation of the volatile organic compounds (VOCs) responsible for rancid flavour in raw lamb meat. The lamb diet was supplemented during the fattening stage with two levels (200 and 400 mg/kg feed) of a dietary rosemary extract (DRE) containing carnosic acid and carnosol (1 : 1, w/w). The formation of VOCs (determined by headspace solid-phase microextraction at 40°C and MS) and odour deterioration (assessed by quantitative descriptive analysis) were monitored in meat fillets (longissimus dorsi-lumborum muscle) packed in a 70/30 O2/CO2 protective atmosphere and kept at 2°C for up to 14 days. The raw meat odour deteriorated under pro-oxidizing conditions due to the development of an incipient rancidity caused by the formation of volatiles from lipid oxidation. A total of 46 volatile compounds were determined in lamb headspace: 18 aldehydes, seven alcohols, seven organic acids, six ketones, four furan compounds, two benzene compounds, one ester and one terpenoid. The use of DRE contributed to inhibit VOC formation and rancidity. Heptanal, octanal, nonanal and 2-pentyl-furan were the only VOCs affected (P<0.05) by the diet at any storage time. In general, VOC formation rate during storage was lower (P<0.05) in the meat from lambs that received a diet supplemented with 400 mg DRE/kg feed than in the meat from lambs receiving no dietary supplementation. VOC inhibition was less effective when the dose of DRE was reduced to 200 mg/DRE kg, although it depended on the VOC analysed. The intensity of rancid odour correlated (P<0.05) with the values of 43 of the 46 VOCs. The highest coefficients were obtained for octanol and octanal (R>0.75; P<0.001), although similar values were obtained for the coefficients of a large number of carbonyl, alcohols and furan compounds, among other volatiles, which can be considered molecular markers of rancidity in raw lamb meat. Principal component analysis confirmed that the differences in the VOC profile make it possible to identify whether or not samples have been reinforced with dietary rosemary diterpenes. Thus, VOC profiling can be regarded as a useful tool for assessing the dietary treatments used in sheep to improve the oxidative stability of lamb meat.

Current research on dietary antioxidants misses the so-called non-extractable polyphenols (NEPP), which are not significantly released from the food matrix either by mastication, acid pH in the stomach or action of digestive enzymes, reaching the colon nearly intact. NEPP, not detected by the usual analytical procedures, are made up of macromolecules and single phenolic compounds associated with macromolecules. Therefore, NEPP are not included in food and dietary intake data nor in bioavailability, intervention or observational studies. The present paper aims to provide an overview of dietary NEPP – nature, occurrence in diet, metabolic fate and possible health effects. NEPP are a relevant fraction of dietary polyphenols exerting their main biological action in the colon, where they are extensively fermented by the action of microbiota, giving place to absorbable metabolites. NEPP exhibit different potential health-related properties, in particular in relation to gastrointestinal health, such as increases in antioxidant and antiproliferative capacities, reduction of intestinal tumorigenesis and modification of gene expression, as observed in different animal models. Further research into NEPP may provide a better understanding of the health effects of dietary antioxidants.

It has been suggested that antioxidants attenuate oxidative stress and prevent oxidative stress-related diseases. Paradoxically, randomised controlled trials (RCT) using pharmacological doses of antioxidant supplements have demonstrated harmful effects in smokers. The aim of the present study was to test the compliance, tolerability and safety of two food-based antioxidant-rich diets in smokers. One of the diets provided antioxidants at levels similar to that used in RCT using supplements which previously have generated harmful effects. The present study followed a randomised, parallel-arm dietary intervention for 8 weeks (n 102) in male smokers (age ≥ 45 years). Participants were randomised to either antioxidant-rich diet, kiwi fruit or control groups. The antioxidant-rich foods provided about 300 mmol antioxidants/week from a wide range of plant-based food items. The kiwi fruit group consumed three kiwi fruits/d. Compliance to both diets was good. Only mild, undesirable events were reported by a minority of the participants. The safety of both diets was demonstrated as no potentially harmful or pro-oxidative effects were observed. In the antioxidant-rich diet group, the mean intake of antioxidants increased from 30 mmol/d at baseline to 62 mmol/d during the intervention. In conclusion, we have demonstrated that male smokers can comply with two food-based antioxidant-rich diets. Furthermore, the present study is the first to demonstrate the tolerability and safety of dietary antioxidants at levels similar to dosages provided in RCT using supplements. Such diets may be useful in future studies investigating whether dietary antioxidants may reduce oxidative stress and related diseases.

There is limited knowledge about the possible effect of unabsorbed dietary antioxidants that reach the large intestine on bowel habits. The aim of the present study was to investigate whether a dietary recommendation directed to increase diet total antioxidant capacity (TAC) is able to affect gut function in human subjects. In this cross-over intervention, nineteen subjects followed a high-TAC (HT) and a low-TAC (LT) diet for 2 weeks, which were comparable for energy, macronutrient, total dietary fibre and alcohol contents. At the end of each intervention period, the 48 h stool output was recorded. In the faecal samples obtained from a subset of nine subjects, moisture, pH, ammonia content, Lactobacillus and Bifidobacterium counts, faecal water antioxidants and genotoxicity were measured. A 3 d weighed food record was used to assess the diet composition during HT and LT diet intake. Significant increases in the intake of TAC, vitamins E and C and phenolic compounds were observed during the HT diet intake. The higher intake of antioxidants led to increased 48 h stool output (324 (sd 38) g in HT v. 218 (sd 22) g in LT), and to higher TAC and total phenolic concentrations in faecal water. No significant variation in the other measured parameters was observed between the diets. In conclusion, a diet selected to raise the intake of dietary antioxidants is able to increase stool bulk and antioxidant content of faeces.

This article describes the principles and limitations of methods used to investigate reactive oxygen species (ROS) protective properties of dietary constituents and is aimed at providing a better understanding of the requirements for science based health claims of antioxidant (AO) effects of foods. A number of currently used biochemical measurements aimed of determining the total antioxidant capacity and oxidised lipids and proteins are carried out under unphysiologcial conditions and are prone to artefact formation. Probably the most reliable approaches are measurements of isoprostanes as a parameter of lipid peroxidation and determination of oxidative DNA damage. Also the design of the experimental models has a strong impact on the reliability of AO studies: the common strategy is the identification of AO by in vitro screening with cell lines. This approach is based on the assumption that protection towards ROS is due to scavenging, but recent findings indicate that activation of transcription factors which regulate genes involved in antioxidant defence plays a key role in the mode of action of AO. These processes are not adequately represented in cell lines. Another shortcoming of in vitro experiments is that AO are metabolised in vivo and that most cell lines are lacking enzymes which catalyse these reactions. Compounds with large molecular configurations (chlorophylls, anthocyans and polyphenolics) are potent AO in vitro, but weak or no effects were observed in animal/human studies with realistic doses as they are poorly absorbed. The development of -omics approaches will improve the scientific basis for health claims. The evaluation of results from microarray and proteomics studies shows that it is not possible to establish a general signature of alterations of transcription and protein patterns by AO. However, it was shown that alterations of gene expression and protein levels caused by experimentally induced oxidative stress and ROS related diseases can be normalised by dietary AO.

The involvement of free radicals and reactive oxygen and nitrogen species in the pathology of inflammatory and degenerative disease has been widely accepted, although the centrality of these species to the outcome of these diseases is still a matter for debate. In the case of CVD, and particularly the development of the atherosclerotic plaque, the oxidation of LDL is of particular importance and appears to explain many of the events that occur during the life history of the plaque. The corollary of this situation is that antioxidants must be a benign force to protect the population from the modern scourge of heart disease. In fact, recent evidence from intervention studies with large doses of the antioxidant vitamins and other antioxidants in foods has been very disappointing. Here, the background for the belief that antioxidants ought to be beneficial is examined and an attempt made to explain why the results of these intervention studies have been unsuccessful. It is agreed that a diet rich in fruit and vegetables is protective for both CVD and cancer, but the explanation for this effect may not necessarily lie with the presence of antioxidants.