Dose-response effects of boiled carrots and effects of carrots in lactic acid in mixed meals on glycaemic response and satiety.

ABSTRACT

OBJECTIVE: To evaluate the effect of dosage on the metabolic response to vegetables added to a mixed lunch meal, and to relate the amounts to the tripartite plate model. Carrots were chosen as an example, and the carrots were blanched, frozen and boiled to include possible effects of processing and cooking. The effects of carrots steeped in lactic acid, as produced at fermentation, were also studied. DESIGN: The test meals with carrots, and the control meal without vegetables, were balanced regarding energy (2000 kJ) and digestible carbohydrates (60 g) and similar in fat (17 g) and protein (16-19 g) content. The carrot portions of 100, 200 and 300 g contained 2.9, 5.8 and 8.7 g dietary fibre respectively. The meals were served in the morning after an overnight fast and in random order. Blood samples for the analysis of blood glucose, plasma insulin and C-peptide were collected and satiety was graded until 210 min postprandially. SETTING: The study was performed at the research laboratory, Dalby Health Sciences Centre (primary care). SUBJECTS: The 10 healthy, male volunteers, around 40 years of age, were recruited at random from the district's population list. None dropped out. RESULTS: The larger the carrot portion the lower were the glucose and insulin/C-peptide responses and the higher the satiety scores. The minimum amount causing significant effects was 200 g. According to the plate model, 200 g of boiled carrots was the most that could be included on half the plate. Addition of lactic acid to 200 g carrots augmented the effects on satiety scores and hormonal response. CONCLUSIONS: The addition of generous amounts of vegetables to a mixed meal improves the metabolic response.