The overarching goal of this project is to determine whether the effect of gut microbiota on human metabolism might be mediated by short chain fatty acids (SCFA) and whether the SCFA might modulate lipid metabolism.
This would be the first study determining the effect of SCFA synthesis on hepatic de novo lipogenesis and to assess whether and how isocaloric dietary changes (namely low carbohydrates) might modify the composition of the gut microbiota and reduce the synthesis of SCFA during adolescence, a sensitive period for the development of obesity.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
38
The experimental diet will consist of 30% carbohydrates (CHO), 35% protein, and 35% fat. Since the experimental diet is lower in CHO, the fiber and sugar content will be calculated based on total CHO in the same percentage as the control (0.25 g fiber per each kcal of CHO and 18.2% sugar for total CHO).
The control diet composition will follow the American Dietary Guidelines of 55% carbohydrates (CHO), 15% protein, and 30% fat. CHO content will be primarily complex CHO of high quality (14 g fiber/1,000 kcals and \<10% of total kcals in the form of sugar).
Hospital Research Unit
New Haven, Connecticut, United States
Rate of Appearance of Acetate
Starting at 08:00, we began a 10-h, primed, continuous, peripheral venous infusion of 99% sodium \[d3\]-acetate with a priming dose of 200 μg · kg-1 · min-1 for 4 min and a continuous infusion rate of 59.5 μg · kg-1 · min-1 for 10 h. After 180 min from the start of the infusion, subjects received 20 g of lactulose per os, dissolved in 30 mL of water.
Time frame: Pre lactulose (average values at 2, 2.5, 3 hours) and Post lactulose (average of values at 7, 8, 9 and 10 hours)
Percent of Hepatic de Novo Lipogenesis.
The percent of hepatic de novo lipogenesis (DNL) refers to the proportion of fatty acids in the liver that are derived from a de novo synthesis pathway, rather than from dietary sources.
Time frame: Pre lactulose (average values at 2, 2.5, 3 hours) and Post lactulose (average of values at 7, 8, 9 and 10 hours)
Change in the Rate of Appearance of Acetate
The changes in rate of appearance of acetate (RaAcetate) are measured averaging the basal RaAcetate 9 timepoints (2 and 3 hours) and the post-lactulose RaAcetate (timepoints 7, 8, 9 and 10 hours).
Time frame: Pre lactulose (average values at 2, 2.5, 3 hours) and Post lactulose (average of values at 7, 8, 9 and 10 hours)
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