**2.4.2 Food judged to be "limited-suggestively" reduced cancer risk**

Since there was not sufficient evidence to judge, the factors below were concluded as limited-suggestive; non-starchy vegetables (not including salted and/or pickled products), fruits, foods containing folate, foods containing selenium, fish, foods containing vitamin D, and selenium (supplements at the dose of 1200 mg/day).

#### **2.4.2.1 Fruit and vegetable**

It is quite complicated to investigate which nutrient has the most effective properties for colorectal cancer prevention, since non-starchy vegetables are a source of dietary fibre, carotenoids, folate, selenium, glucosinolates, and so on, and fruits are sources of vitamin C, carotenoids, phenols, flavonoids and other anti-oxidants. The results of the anti-cancer effects of fruit and vegetable are heterogeneous.

Dietary cruciferous vegetable intake was associated with a reduced colon risk of approximately 25% (Marshall, 2008), There was an inverse association between the consumption of fruits and the risk of colorectal cancer, although the vegetarians showed a moderate, but non-significant, decrease in the risk (Sanjoaquin et al., 2004). A high consumption of vegetable and fruit showed an inverse association with colorectal and colon cancer, but not rectal cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC). There was no significant inverse association shown between vegetable consumption or fruit consumption and colorectal, colon, or rectal cancer (Key et al., 2009; van Duijnhoven et al., 2009).

Vegetable-fruit mixture intake did not decrease the number of colon polyps both in low in fat (20% of energy) and high in fat (40% of energy) in the *Apc*Min mice which are genetically predisposed to intestinal polyps (van Kranen et al., 1998).

It has been reported that several fruits have a specific potency for cancer prevention. Apple is rich in quercetin (World Cancer Research Fund, 2007c). Apple juice also showed the potency of preventing colon carcinogenesis in mice, but this effect was not found under the cancer promoting conditions associated with obesity (Koch et al., 2009). On the other hand, Nandir et al. showed apple pomace increased the number and diameter of colon polyps in *Apc*Min mice (Mandir et al., 2008). Citrus fruits are sources of antioxidants, such as vitamin C, phenols, flavonoid and bioactive phytochemicals. Vitamin C traps free radicals and reactive oxygen species, and protects DNA from mutagenic damage (World Cancer Research Fund, 2007c). Cruciferous vegetables, such as broccoli, cabbage and cauliflower, reduced the colorectal cancer risk (Marshall, 2008), although there was also a negative report (Graham et al., 1988).
