The objectives of the study are 1) to determine the influence of daily consumption of well-cooked broccoli on plasma and urinary glucosinolate metabolites, and 2) to determine inflammatory marker changes consistent with decreased cancer risk.
Consumption of Brassica vegetables is inversely associated with incidence of several cancers, including cancer of the lung, stomach, liver, colon, rectum, breast, endometrium, and ovaries. Brassica vegetables are a good source of many nutrients, but the unique characteristic of Brassicas (Broccoli in particular) is their rich content of glucosinolates. Glucosinolates are sulfur-containing compounds that are converted to isothiocyanates (ITC) by an enzyme in the plant called myrosinase, which is released when the vesicles containing myrosinase are ruptured by chewing or cutting. The isothiocyanates are considered to be the active agent for cancer prevention. Some of the mechanisms by which isothiocyanates likely inhibit cancer include modulation of cytochrome P450 enzymes, induction of phase II enzymes, and apoptosis. The aim of this study is to investigate how daily consumption of broccoli with myrosinase inactivated by cooking influences glucosinolate metabolism and absorption, and consequent regulation of inflammatory markers.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
DOUBLE
Enrollment
18
Participants will receive a controlled diet with 0 g/d of broccoli. Meals will be prepared using traditional American foods with a macronutrient composition representative of a typical American diet.
Participants will receive a controlled diet with 100 g of broccoli at both breakfast and dinner daily. Meals will be prepared using traditional American foods with a macronutrient composition representative of a typical American diet.
USDA-ARS, Beltsville Human Nutrition Research Center
Beltsville, Maryland, United States
The change in glucosinolate metabolites will be measured in blood plasma and urine
To track the change of endogenous broccoli isothiocyanates in this crossover study, glucosinolate metabolites will be measured in both blood plasma and urine
Time frame: At end of diet period 1 (week 3) and at the end of diet period 2 (week 12)
Body composition will be determined by dual energy x-ray absorptiometry (DEXA)
Determine fat, lean, and bone mineral mass, and visceral fat deposition in our subjects
Time frame: Day 0, just prior to beginning the controlled diet
The ability of fecal microbiota to metabolize glucosinolates will be determined
Fecal samples will be presented with glucoraphanin to determine the ability of fecal microbes to metabolize it
Time frame: once per week during diet periods 1 and 2 (weeks 1, 2, 3, 10, 11, and 12)
Fecal microbiota will be analyzed for microbial DNA
Fecal microbial communities will be determined using DNA extracted from fecal samples
Time frame: once at the beginning and end of diet periods 1 and 2 (weeks 1, 3, 10, and 12)
Markers of gut health will be analyzed in blood
Zonulin in blood serum will be measured by ELISA
Time frame: once in the third week of diet periods 1 and 2 (weeks 3 and 12)
Markers of inflammation will be measured in blood
Cytokines and acute phase proteins will be measured in blood
Time frame: at end of diet period 1 (week 3) and at end of diet period 2 (week 12)
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