Chemistry Reference
In-Depth Information
6.7 INTErACTIoN WITh oThEr NuTrIENTs
Resistant starch (10 percent HACS) not only protected against intestinal carcino-
genesis but also ameliorated the tumor-enhancing effects of dietary resistant protein
(Morita et al., 2004; Le Leu et al., 2007b). Feeding resistant protein increased protein
fermentation products, but this effect was reduced by adding RS to the diet. Intestinal
neoplasms and colorectal adenocarcinomas were reduced by feeding RS (
p
< 0.01).
Govers et al. (1999) reported that wheat bran can shift the fermentation of
RS further distally in pigs, thereby improving the luminal conditions in the dis-
tal colonic regions. Authors concluded that the combined consumption of RS and
wheat bran may contribute to the dietary modulation of colon cancer risk. Psyllium
(15 g psyllium/kg diet) delayed the fermentation rate of HACS diets (50 g/kg diet)
in the cecum and shift the fermentation site of HACS toward the distal colon, lead-
ing to the higher butyrate concentration in the distal colon and feces (Morita et al.,
1999). Resistant starch altered the colonic luminal environment by increasing the
concentration of SCFAs including butyrate and lowering production of potentially
toxic protein fermentation products.
6.8 rs INTAkE IN ThE uNITED sTATEs
Recent National Health and Nutrition Examination Survey (1999-2002
NHNAES) indicated that Americans aged 1 year and older consumed approximately
4.9 g RS per day (Murphy et al., 2008). Resistant starch intake was highest for men
aged 20 to 49 years whose daily mean intake level was 5.9 g. Adult women had a
mean intake of 4.3 g; children aged 1 to 5 years, 3.7 g; and older children aged 6 to
11 years, 4.2 g. Top sources of RS were breads, cooked cereals/pastas, and vegetables
(other than legumes) and these foods contributed 21, 19, and 19 percent of total RS
intake, respectively. In 10 different European countries, the mean daily RS intake
has been estimated at 4.1 g per person (a range of 3.2 to 5.7 g; Asp et al., 1996). Per
capita daily dietary fiber intake in the United States has been estimated to be in the
range of 16 to 18 g (Cho, unpublished data), which is far below recommended intake
levels (adult men aged 19 to 50 years, 35 g/day; adult women 25 g/day; IOM, 2002).
It is imperative to increase the dietary fiber intakes of the western population to meet
recommended intake levels.
6.9 CoNClusIoNs
The results of this chapter suggest that RS may be used to selectively modify gut
function and that increasing butyrate availability may improve colonic health. HACS
and the various commercial ingredients derived from them have been the focus of most
of the studies regarding prebiotic and symbiotic effects. Given the current interest in
developing new sources of commercial RS, there is great potential to increase the RS
intake as well through consumption of many different types of processed foods.
