Stoll BA
Oncology Department, St. Thomas' Hospital, London, UK.
Br J Cancer 1996 Mar;73(5):557-9
Case-control studies in diverse populations around the world have
reported a lower risk of breast cancer in association with
higher intake of dietary fibre and complex carbohydrates. Although
this has not been confirmed in prospective studies in the USA, the observations have
prompted the hypothesis that prolonged use of dietary fibre supplements might reduce
breast cancer risk in high-incidence populations.
Several possible mechanisms of action have been suggested, all involving a reduction of bioactive oestrogen levels in the blood. The various mechanisms are not necessarily mutually exclusive.
 First, a high-fibre diet might reduce circulating oestrogen levels by reducing
the enterohepatic recirculation of oestrogen. |
| Second, many plants and vegetables contain isoflavones and lignans capable of
conversion in the bowel into weak oestrogens that may compete with oestradiol for target
binding-sites. |
| Third, a high-fibre diet is less often associated with obesity, which tends to
increase availability of the biologically active 16-alpha metabolites of oestrone. |
| Finally, diets rich in fibre and complex carbohydrates have been shown to improve
insulin sensitivity, with an associated reduction in circulating oestrogen levels.
Synergism between these effects offers a possible mechanism by which a high fibre intake
might suppress breast cancer growth in women. |
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