In this well-nourished population, vitamin A consumption was considerably higher than recommended, and liver reserves were consistent with intake. Because of their sensitivity, stable-isotope techniques can help to describe the vitamin A status and better characterize the intake needs of all groups defined in the Dietary Reference Intakes. Registration was not required for this trial.

For obese individuals seeking to optimize health and well-being, healthy dietary strategies are important. Vegetables and fruits contribute to a healthy diet, and increased consumption may cause weight reduction by displacing foods high in energy and fat. The objective of this study was to determine if advising high vegetable (8 servings) and moderate fruit (2-3 servings) consumption would result in weight reduction in obese individuals. We compared this to advising a more traditional strategy of reducing daily energy intake by 500 kcal (2.1 MJ)/d and limiting energy from fat to

This piglet model suggests that, for supplementation to infants <6 mo old, a 50000-IU dose is likely to be more efficacious in mitigating deficiency than is a 25000-IU dose.

The natural isotopic composition of 13 C and 12 C in tissues is largely determined by the diet. Sources of provitamin A carotenoids (e.g., vegetables) typically have a lower 13 C to 12 C ratio ( 13 C: 12 C) than preformed vitamin A sources (i.e., dairy and meat) from corn-fed animals, which are prevalent in the US. The 13 C: 12 C of serum retinol ( 13 C: 12 C-retinol) was evaluated as a biomarker for vegetable intake in a 3-mo dietary intervention designed to promote weight-loss by increased vegetable consumption or reduced calorie and fat intake. Subjects were 21-50 y of age with a BMI between 30-40 kg/m 2 and were enrolled from one geographic area in the US. The high vegetable group (n = 20) was encouraged to increase daily vegetable and fruit consumption to 0.95 liter vegetables and 0.24-0.35 liter fruits. The caloric reduction group (n = 17) was encouraged to lower caloric intake by 500 kcal and consume ≤25% kcal from fat daily. Provided meals supplied 75-100% vegetable and fruit goals and 50-67% kcal and fat g per day. Carotenoid supplementation was discontinued by subjects during the study. Serum retinol and provitamin A carotenoid concentrations; intake of preformed vitamin A, provitamin A, and fat; and body weight, fat mass, and lean mass were analyzed for correlations to 13 C: 12 C-retinol. 13 C: 12 C-Retinol decreased in the vegetable group after intervention (P = 0.050) and the correlation with provitamin A intake was approaching significance (P = 0.079). 13 C: 12 C-Retinol did not change in the caloric reduction group (P = 0.43). 13 C: 12 CRetinol changes with the vitamin A source in the diet and can be used as a biomarker for increases in dietary provitamin A vegetable intake.