Health Effects of Oligosaccharides (continued)

CH,-OH
J—— o
HO-CHjxO
HO-CH2.0
n: 1-3
(a) Fruclooligosaccharides
HjC-OH
n: 1-4
(b) Galactooligosaccharides
n: 1 (raffinose) n: 2 (stachyose)
oh	oh
(c) Soybean oligosaccharides
Fig. 1—Chemical structures of some physiologically functional oligosaccharides
OU-OH
ticularly marked in senility (Honma and Mitsuoka, 1978; Kanbe, 1992a). The decrease has been postulated as one of the important causes of aging, immunity decreases, and adult diseases such as cancer and arthritis (Drasar and Hill, 1974f; Mitsuoka, 1990a, b; Mizutam, 1992).
Mental stresses, which are already known to affect human health through hormonal disturbance, also change the intestinal microflora profile, drastically decreasing bifidobacteria and increasing detrimental bacteria (Komai, 1990).
The average life span of germ-free mice having no intestinal microflora is 50% longer than that of controls (Mitsuoka, 1990b; Komai and Nanno, 1992). The average life span of C3H mice fed a diet containing 0.5% antioxi-dant is about 20% longer than that of controls (Comfort et al, 1971). This indicates that the harmful effects of microflora on human health are comparable to that of free-radical oxidation. The aggravating effects of detrimental microflora in liver carcinogenesis was demonstrated using mice (Mitsuoka, 1982).
Benefits of Oligosaccharide Ingestion
A number of health benefits result from ingestion of oligosaccharides.
• Proliferation of Bifidobacteria and Reduction of Detrimental Bacteria. Human studies have shown an increase in bifidobacteria resulting from oligosaccharide ingestion and a reduction in detrimental bacteria such as Clostridium perfringens (Hidaka et al., 1986; Takahashi et al., 1986; Masai et al., 1987; Benno et al., 1987; I to et al., 1990; Wada et al., 1991). Ingestion of 2-10 g/day for several weeks effectively increased bifidobacteria population in the human intestine an average of 7.5 times and decreased C. perfringens an average of 81%; with some oligosaccharides, lactobacilli also increased 2-3 times. C. perfringens decreased by 0.5— 0.06 times (p<0.05).
Bifidobacteria prevent the growth of exogenous pathogenic microbes and the excessive growth of indigenous detrimental microflora through production of short-chain fatty acids (mainly acetic acid and lactic acid at a 3:2 mole ratio) and an ability to produce some antibiotic materials.
The growth-inhibiting and destructive effects of acetic and lactic acids on undesirable bacteria are known (Rasic and Kurmann, 1983). The suppressive effects of these acids against Salmo-
62   FOOD TECHNOLOGY—OCTORERia°4

nello. (Chung and Goepfert, 1970) and E. coli (Tamura, 1983) were reported. Bifidin, an antibiotic produced byBifi-dobacterium bifidum, is effective against Shigella dysenteriae, Salmonella typhosa, Staphylococcus aureus, E. coli, and other bacteria (Anand et al., 1984, 1985). A high-molecular-weight substance from Bifidobacte-rium infantis is also effective against Shigella flexneri 5503-01, S. faecalis, E. coli, and others (Nakaya, 1984; Okamura et al., 1986).
• Reduction of Toxic Metabolites and Detrimental Enzymes. Reduction of toxic metabolites and detrimental enzymes by oligosaccharide ingestion has been shown in human tests and in-vitro human-feces culture tests (Takahashi et al., 1986; Masai et al., 1987; Wada et al., 1991; Kato et al., 1992; Saito et al., 1992; Mutai, 1978).

The ingestion of 3-6 g/day or the • equivalent addition of oligosaccharide to human feces in in-vitro culture reduced intestinal toxic compounds and detrimental enzymes an average of 44.6% and 40.9%, respectively, in about 3 weeks.
• Prevention of Pathogenic and Autogenous Diarrhea. Ingestion of oligosaccharides or bifidobacteria prevents pathogenic and autogenous diarrhea by the same mechanisms as described in the reduction of detrimental bacteria. For example: (1) Ingestion of 8.0 g of fructooligosaccharides per day by 6 aged patients who had loose stools improved the stool conditions to normal after 8 days in all subjects (Hidaka et al., 1986). (2) Ingestion of 3.0 g/day of a bifidobacteria preparation containing 10 x 10'° Bifidobacteria breve cells/g, by 15 patients ages 1 mo—15 yr with in-