Food intake was weighed and recorded daily during one complete menstrual cycle in 18 healthy normally menstruating women. Urinary luteinizing hormone indicated the time of ovulation. Mean daily intakes of energy, macronutrients, and alcohol were calculated for five phases during the menstrual cycle: menses, postmenses, ovulatory, postovulatory, and premenses. Weekly variations were also measured. Energy intake was lowest during the ovulatory phase compared with postovulatory, premenses, and menses phases (p less than 0.05). The maximum difference, 1.36 MJ (324 kcal)/d, occurred between ovulatory and postovulatory phases and was twofold higher than the increase of 0.64 MJ (152 kcal)/d observed at weekends. This reduction of food intake at ovulation has not been previously described in humans. It coincides with the expected peak in circulating estrogen levels and is consistent with the hypothesis in animal models that estrogen is an appetite suppressant.

We compared the effects on the ratio of plasma tryptophan to large neutral amino acids (trp:LNAA) of two different carbohydrate meals (sucrose or starch, 120 g) and a contrasting meal of fat + protein given at breakfast to 10 healthy adults. Plasma glucose and insulin were also measured. The trp:LNAA ratio rose after both carbohydrate meals (p less than 0.001). Glucose and insulin peaks were higher after sucrose than starch, and trp:LNAA rose correspondingly higher (sucrose +34% and starch +20%, p less than 0.05). The ratio declined 45% after the fat + protein meal. At 180 min, absolute ratio values were twofold higher after carbohydrate (sucrose 0.133 and starch 0.127) than after fat + protein (0.057). Similar results were found with the same meals given in the evening. Our results suggest that high-carbohydrate meals have an influence on serotonin synthesis. We predict that carbohydrates with a high glycemic index would have a greater serotoninergic effect than carbohydrates with a low glycemic index.

Purple sweetcorn has been conceptualized as an innovative premium horticultural product that may provide consumers with the potential health benefit of anthocyanins. Gathering consumer insights is crucial to inform the breeding program to obtain a purple sweetcorn product closer to consumer’s requirements. Thirty-six non-food neophobic sweetcorn consumers participated in a focus group session on the concept of purple sweetcorn, as well as visually evaluating early breeding lines. Consumers were very positive about the concept of purple sweetcorn and had clear ideas of potential uses. Consumers preferred that purple sweetcorn taste different to commercial yellow sweetcorn, and that health claims would support a premium price position. A small scale follow up consumer study (n = 10) was carried out where consumers were asked to rate acceptability for visual (raw and cooked), flavour, textural and overall of two purple sweetcorn breeding lines (reddish-purple and purple) and compared against commercial yellow sweetcorn. Visual acceptability scores were higher for purple than the reddish-purple lines for both cooked and raw forms, but the yellow cobs were the most preferred. In contrast, flavour and overall acceptability scores were higher for the reddish-purple and yellow cobs than the purple lines. It was also noted that the reddish-purple and purple lines had a slight raspberry flavour. Consumer’s discussions outcomes from both studies were that consumers preferred better color coverage across the kernel, which will be the direction in continuing the development of purple sweetcorn lines. This study demonstrated there is a market for a premium purple sweetcorn product among consumers.