Wild berries are part of traditional Nordic diets and are a rich source of phytochemicals, such as polyphenols. Various berry treatments have shown to interfere with cancer progression in vitro and in vivo. Here, we systematically reviewed the anticancer effects of two Nordic wild berries of the Vaccinium genus, lingonberry (Vaccinium vitis-idaea) and bilberry (Vaccinium myrtillus), on digestive tract cancers. The review was conducted according to the PRISMA 2020 guidelines. Searches included four databases: PubMed, Scopus, Web of Science, and CAB abstracts. Publications not written in English, case-reports, reviews, and conference abstracts were excluded. Moreover, studies with only indirect markers of cancer risk or studies with single compounds not derived from lingonberry or bilberry were not included. Meta-analysis was not performed. The majority (21/26) of studies investigated bilberry and colorectal cancer. Experimental studies on colorectal cancer indicated that bilberry inhibited intestinal tumor formation and cancer cell growth. One uncontrolled pilot human study supported the inhibitory potential of bilberry on colorectal cancer cell proliferation. Data from all 10 lingonberry studies suggests potent inhibition of cancer cell growth and tumor formation. In conclusion, in vitro and animal models support the antiproliferative and antitumor effects of various bilberry and lingonberry preparations on digestive tract cancers.
Keywords: anthocyanin; bilberry; colorectal cancer; invasion; lingonberry; migration; oral cancer; phytochemical; polyphenol; proanthocyanidin; proliferation; tumorigenesis.