Monday, August 22, 2016
Steamed greens for detoxification
Steam cooking significantly improves in vitro bile acid binding of collard greens, kale, mustard greens, broccoli, green bell pepper, and cabbage
Vegetarians or those consuming vegetables as a major portion of their daily diet along with lower calories from saturated fat and animal products are at a lower risk of coronary heart disease and cancer. Vegetables are a good source of dietary fiber, antioxidants, phytonutrients, provitamins, polyphenols, and minerals. The US Department of Agriculture (USDA) Food and Nutrition Information Center, through the Food Guide Pyramid—Steps to a Healthier You ( http://www.mypyramid.gov ), recommends the consumption of dark leafy and colorful vegetables and low-fat food products along with daily active life and maintaining desirable body weight  . Some of the vegetables listed by the USDA food pyramid include collard greens, kale, mustard greens, broccoli, and spinach. Isothiocyanates of the cruciferous vegetables in the Brassica family have been shown to protect against various types of cancers 2 3 4 5 . Sulforaphane, indole-3-carbinol, glucaric acid, and other isothiocyanates are antioxidants and potent stimulators of natural detoxifying enzymes in the body. These compounds are believed to be responsible for the lowered risk of atherosclerosis and cancer [6 7] . Toxic metabolites in the gut and secondary bile acids increase the risk of colorectal cancer  . Atherosclerosis and cancer are 2 leading causes of death and disability in the developed world and are increasing rapidly in the developing world. These are the major human nutrition problems and are preventable with diet and physically active lifestyle. The healthful, cholesterol-lowering (atherosclerosis amelioration) or detoxification of harmful metabolites (cancer prevention) potential of food fractions could be predicted by evaluating their in vitro bile acid binding, based on positive correlations found between in vitro and in vivo studies showing that cholestyramine (bile acid–binding, cholesterol-lowering drug) binds bile acids and cellulose does not 9 10 11 12 . Bile acids are acidic steroids synthesized in the liver from cholesterol. After conjugation with glycine or taurine, bile acids are secreted into the duodenum. Bile acids are actively reabsorbed by the terminal ileum and undergo an enterohepatic circulation  . Binding of bile acids and increasing their fecal excretion have been hypothesized as a possible mechanism by which food fractions lower cholesterol 14 15 16 . The bile acids are needed for the absorption of dietary fat from the gastrointestinal tract. The dietary fat is a precursor of cholesterol synthesis in the body. By binding bile acids, food fractions prevent their reabsorption and stimulate plasma and liver cholesterol conversion to additional bile acids 17 18 19 20 . Excretion of toxic metabolites and secondary bile acids could lower the risk of cancer  . The bile acid binding of grain fractions, ready-to-eat cereals, and various dry beans has been observed to be proportional to their dry matter (DM) content 21 22 23 24 . Steam cooking beets, eggplants, asparagus, carrots, green beans, and cauliflowers significantly improved in vitro bile acid binding compared with the values obtained for these vegetables uncooked  . In vitro bile acid binding of the following vegetables has been reported: uncooked spinach, 9%; kale, 8%; Brussels sprouts, 8%; broccoli, 5%; mustard greens, 4%; green bell peppers, 3%; cabbage, 2%; and collard greens, 2%  . Vegetables are normally cooked before their consumption; how cooking would influence bile acid binding of these green/leafy vegetables is the subject of this report.