n six healthy subjects serum cholesterol was unchanged during a 2-wk period of controlled diet (2750 kcal) followed by a 2-wk period of free diet but showed a 16% decrease (p less than 0.05) during a further 2-wk period of controlled diet to which guar (5.7 g bid) was added. Stool weight, frequency and whole gut transit time did not differ in the diet periods with and without guar. Of guar ingested 82-95% was metabolized in the gut. Mouth to cecum transit of a meal measured by the hydrogen breath test in the same subjects was unaffected by the addition of 5.7 g of guar