Broccoli: Stability of Its Nutrients During Digestion

Broccoli (Brassica oleracea) is a rich source of phytochemicals that may have significant health benefits. In particular, broccoli contains high amounts of polyphenols, glucosinolates and vitamin C, and these nutrients may explain its ability to reduce the risk of certain diseases including cancer. However, the presence of nutrients does not guarantee health effects, as the nutrients must survive digestion and then be absorbed. For example, around 69 % of glucosinolates may be lost during digestion in the stomach, although the remaining glucosinolates remain relatively stable in the intestine. In contrast, the vitamin C content of broccoli may be more stable with only 7 % loss during digestion in the stomach. During digestion, polyphenols are extensively degraded with an 80 to 84 % loss in the intestine, but much lower degradation in the stomach of around 6 to 25 %. The losses associated with nutrients in broccoli are determined by the exact conditions of digestion, and therefore losses may differ depending on the presence of other foods, as well as showing differences between individuals. Further, while phytochemicals can be degraded during digestion, it might be that the breakdown products are in turn also able to confer health effects. For example, the breakdown products of polyphenols may be absorbed and may provide many of the effects attributed to polyphenols themselves. Bacterial degradation of polyphenols in the small and large intestine is likely extensive. 

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Vallejo, F., Gil-Izquierdo, A., Pérez-Vicente, A. and García-Viguera, C. 2004. In vitro gastrointestinal digestion study of broccoli inflorescence phenolic compounds, glucosinolates, and vitamin C. Journal of agricultural and food chemistry. 52(1): 135-138

About Robert Barrington

Robert Barrington is a writer, nutritionist, lecturer and philosopher.
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