High consumption of olive oil in the Mediterranean diet has been suggested to protect DNA against oxidative damage and to reduce cancer incidence. We investigated the impact of the phenolic compounds in olive oil, and the oil proper, on DNA and RNA oxidation in North, Central, and South European populations. In a multicenter, double-blind, randomized, controlled crossover intervention trial, the effect of olive oil phenolic content on urinary oxidation products of guanine (8-oxo-guanine, 8-oxo-guanosine and 8-oxo-deoxyguanosine) was investigated. Twenty-five milliliters of three olive oils with low, medium, and high phenolic content were administered to healthy males (n=182) daily for 3 wk. At study baseline the urinary excretion of 8-oxo-guanosine (RNA oxidation) and 8-oxo-deoxyguanosine (DNA oxidation) was higher in the Northern regions of Europe compared with Central and Southern European regions (P=0.035). Urinary excretion of the 8 hydroxylated forms of guanine, guanosine, deoxyguanosine and their nonoxidized forms were not different when comparing olive oils with low, medium, and high phenolic content given for 2 wk. Testing the effect of oil from urinary 8-oxo-deoxyguanosine changes from baseline to post-treatment showed a reduction of DNA oxidation by 13% (P=0.008). These findings support the idea that ingestion of olive oil is beneficial and can reduce the rate of oxidation of DNA. This effect is not due to the phenolic content in the olive oil. The higher DNA and RNA oxidation in Northern European regions compared with that in Central and Southern regions supports the contention that olive oil consumption may explain some of the North-South differences in cancer incidences in Europe.

A well-planned vegetarian diet has been stated to be adequate during pregnancy. The aim of the present study was to compare serum vitamin B-12 and homocysteine concentrations in pregnant women (n = 109) consuming vegetarian and Western diets and to evaluate the adequacy of current dietary reference intakes of vitamin B-12 for these women. Pregnant women adhering to vegetarian diets for at least 3 y, with subgroups of ovo-lacto vegetarians (OLVs; n = 27), low-meat eaters (LME, n = 43), and women eating an average Western diet (control group, n = 39), were recruited. Dietary vitamin B-12 intake, serum vitamin B-12, and plasma total homocysteine (tHcy) concentrations were measured in wk 9-12, 20-22, and 36-38 of pregnancy. During pregnancy serum vitamin B-12 concentrations of ovo-lacto vegetarians (P < 0.001) and low-meat eaters (P = 0.050) were lower than those of the control group. We observed the combination of low serum vitamin B-12 concentrations and elevated plasma tHcy in 22% of ovo-lacto vegetarians, in 10% of low-meat eaters, and in 3% of controls (P = 0.003). In OLVs, serum vitamin B-12 predicted 60% of the plasma tHcy variation (P < 0.001), but in LMEs and controls only <10% (NS). Serum vitamin B-12 concentrations increased and plasma tHcy decreased sharply with increasing dietary intake of vitamin B-12 toward a cutoff point of 3 mug/d. Pregnant women consuming a long-term predominantly vegetarian diet have an increased risk of vitamin B-12 deficiency. Current recommended dietary intakes urgently need reevaluation.

Ghrelin is an orexigenic hormone that may affect substrate utilization in humans. Ghrelin is influenced by macronutrients, but the effects of insoluble dietary fiber and polyphenols are unknown. We investigated the effects of a polyphenol-rich insoluble dietary fiber preparation from carob pulp (carob fiber) on postprandial ghrelin responses and substrate utilization. Dose-dependent effects of the consumption of carob fiber were investigated in a randomized, single-blind, crossover study in 20 healthy subjects, aged 22-62 y. Plasma total and acylated ghrelin, triglycerides, and serum insulin and nonesterified fatty acids (NEFA) levels were repeatedly assessed before and after ingestion of an isocaloric standardized liquid meal with 0, 5, 10, or 20 g of carob fiber over a 300-min period. The respiratory quotient (RQ) was determined after consumption of 0 or 20 g of carob fiber. Carob fiber intake lowered acylated ghrelin to 49.1%, triglycerides to 97.2%, and NEFA to 67.2% compared with the control meal (P < 0.001). Total ghrelin and insulin concentrations were not affected by consumption of a carob fiber-enriched liquid meal. Postprandial energy expenditure was increased by 42.3% and RQ was reduced by 99.9% after a liquid meal with carob fiber compared with a control meal (P < 0.001). We showed that the consumption of a carob pulp preparation, an insoluble dietary fiber rich in polyphenols, decreases postprandial responses of acylated ghrelin, triglycerides, and NEFA and alters RQ, suggesting a change toward increased fatty acid oxidation. These results indicate that carob fiber might exert beneficial effects in energy intake and body weight.

Dietary fibre consumption is associated with improved glucose homeostasis. In contrast, dietary polyphenols have been suggested to exert both beneficial and detrimental effects on glucose and insulin metabolism. Recently, we reported that a polyphenol-rich insoluble dietary fibre preparation from carob pulp (carob fibre) resulted in lower postprandial acylated ghrelin levels after a liquid meal challenge test compared with a control meal without supplementation. The effects may, however, differ when a different food matrix is used. Thus, we investigated the effects of carob fibre on glucose, insulin and ghrelin responses in healthy humans in combination with a glucose load. In a randomized single-blind cross-over study involving twenty healthy subjects (aged 22-62 years), plasma glucose, total and acylated ghrelin, and serum insulin were repeatedly assessed before and after the ingestion of 200 ml water with 50 g glucose and 0, 5, 10 or 20 g carob fibre over a period of 180 min. The intake of 5 and 10 g carob fibre increased the plasma glucose by 47 % and 64 % (P,0·001), and serum insulin by 19·9 and 24·8 % (P, 0·001), compared with the control. Plasma acylated ghrelin concentrations did not change significantly after the consumption of carob-enriched glucose solution. Total ghrelin decreased only after 10 g carob fibre (P,0·001) compared with control. In conclusion, we showed that polyphenol-rich carob fibre, administered within a water -glucose solution, increases postprandial glucose and insulin responses, suggesting a deterioration in glycaemic control.

We have recently shown that a polyphenol-rich insoluble dietary fibre preparation from carob pulp (Ceratonia siliqua L; carob fibre) decreased postprandial acylated ghrelin, TAG and NEFA during an acute liquid meal challenge test. However, delayed effects of carob fibre consumption are unknown. Therefore, a randomized controlled crossover study in nineteen healthy volunteers consuming foods with or without 50 g carob fibre was conducted. On the subsequent day (day 2), glucose, TAG, total and acylated ghrelin as well as insulin, NEFA and leptin were assessed at baseline and at timed intervals for 300 min after ingestion of standardized bread. Consumption of carob fibre-enriched foods did not affect fasting concentrations of glucose, TAG, total ghrelin, NEFA, insulin and leptin. Fasting acylated ghrelin was increased on the day subsequent to carob fibre consumption compared with control (P¼0·046). After consumption of the standard bread on day 2, glucose response (P¼ 0·029) was increased, and TAG (P¼0·033) and NEFA (P,0·001) responses were decreased compared with control. Postprandial responses of total and acylated ghrelin, insulin and leptin on day 2 were unaffected by carob fibre consumption the previous day. In conclusion, an increase in total and acylated plasma ghrelin accompanied by enhanced lipid metabolism after carob fibre consumption suggests higher lipid utilization and suppressed lipolysis on the day subsequent to carob fibre consumption. However, elevated glucose levels after carob fibre consumption need to be addressed in future studies.Carob: Insoluble dietary fibre: Polyphenols: Glucose: Insulin: Ghrelin Epidemiological studies clearly show that a high intake of insoluble fibre is associated with a low risk for CVD and diabetes 1 -3 . Beneficial effects of insoluble dietary fibre are also discussed in the context of consumption of whole grain, containing further bioactive compounds such as polyphenols, antioxidants or vitamins. As another potential mechanism for the beneficial effects of dietary fibre, fermentation processes in the colon are discussed resulting in the production of SCFA 4,5 . Polyphenols have been shown to reduce food intake, to lower leptin concentrations 6 and to promote fat oxidation in rats 7 . Recently, we showed that the consumption of a polyphenol-rich insoluble dietary fibre preparation from carob pulp (Ceratonia siliqua L; carob fibre) acutely decreased postprandial TAG and NEFA concentrations, while increasing fat oxidation during a liquid meal challenge test 8 . Elevated circulating TAG and NEFA play a key role in the development of insulin resistance 9 . Impaired whole body insulin resistance is characterized by a lowered ability of skeletal muscle to oxidize fatty acids 9 . Therefore, functional foods lowering circulating NEFA by increasing fat oxidation might be of interest for the prevention and treatment of diabetes and obesity.Obesity is the result of a positive energy balance. Among peripheral hormones regulating energy balance, the orexigenic ghrelin and the ano...