Herbs, spices and gut health 163
the anti-inflammatory activity of aloe vera to its antioxidant properties and inhibitory
effects on colorectal prostaglandin E2 and interleukin-8 production. The activity of
devil’s claw and tormentil is also attributed to flavonoids and tannins respectively
which are proven free-radical scavengers while fenugreek and Mexican yam
contain steroidal saponins which might be able to influence the local inflammatory
response (Vennat et al., 1994; Bos et al., 1996; Langmead et al., 2002). The effect of
commercial preparations of bitter candytuft, chamomile flower, peppermint leaves,
caraway fruit, liquorice root, lemon balm leaves, celandine herbs, angelica root and
milk thistle fruit may be potentially mediated via their influence on gastrointestinal
motility (Okpanyi et al., 1993) possibly via 5-hydroxytryptamine (5-HT) pathways
(Simmen et al., 2003; Madisch et al., 2004). Protection of target tissues from radical
attack from the lumen of the intestine could also be a result of enhancement of
physico-chemical barriers, for example, by increased mucus production (Langmead
et al., 2002).
The antioxidant effect on lipid peroxidation of several compounds such as curcumin,
capsaicin, eugenol, piperine, zingerone, linalool and cuminaldehyde is exerted by
quenching oxygen free radicals and by enhancing the activity of endogenous antioxidant
enzymes – superoxide dismutase, catalase glutathione peroxidase and glutathione
transferase (Srinivasan, 2005).
10.6 Effect on gut immunity..................................................................
Additionally protective effects have been attributed to many herbs and spices and
strengthening of the gut immune system (Table 10.5). Red pepper seems to display
a protective effect on the gastric mucosa (Yeoh et al., 1995). Small doses of their
active compound capsaicin have beneficial (protective) effects against different noxious
agents in the stomach in animal models (Szolcsanyi and Bartho, 1981; Langmead
and Rampton, 2001). Abdel-Salam et al., (1995) indicated that small doses of capsaicin
inhibit gastric acid secretion and prevent the gastric mucosal damage produced by
different acid- and non-acid-dependent gastric mucosal damaging agents (Mozsik et
al., 1997). Results on humans showed that small doses of capsaicin inhibit gastric
basal acid output via stimulation of the inhibition of capsaicin sensitive afferent
nerves (Mozsik et al., 1999).
Ganoderma (G) lucidum, a traditional Chinese herbal medicine that is popular as
a food supplement in Asia is believed to enhance the immune system (Ha, 2003) and
to promote longevity (Shiao et al., 1994). Antitumour activities are the most notably
stimulatory effect on animals subjected to either oral administration (Cheng et al.,
1985), subcutaneous (Cheng et al., 1982), or intraperitoneal (i.p.) injection (Song et
al., 1985) of the hot water extracts of G. lucidum. G. lucidum may have potential
immuno-modulating effects in patients with advanced colorectal cancer (Chen et al.,
2005). Immunomodulatory activity has possessed also been recorded for fenugreek
(Trigonella foenum graecum L.) on mice. Plant extract elicited a significant increase
in phagocytic index and phagocytic capacity of macrophages (Bin-Hafeez et al.,
2003).
The anticarcinogenic properties of basil and cumin were tested on the induction of
squamous cell carcinomas in the stomach of Swiss mice and on induction of hepatomas
in Wistar rats and it was found that they significantly decreased the incidence of both
neoplasia and hepatomas (Aruna and Sivaramakrishnan, 1992).