Obesity and its related metabolic abnormalities, including
insulin resistance, alterations in the
insulin-like growth factor-1 (IGF-1)/
IGF-1 receptor (IGF-1R) axis, and the state of chronic
inflammation, increase the risk of
colorectal cancer (CRC) and
hepatocellular carcinoma (HCC). However, these findings also indicate that the metabolic disorders caused by
obesity might be effective targets to prevent the development of CRC and HCC in obese individuals.
Green tea catechins (GTCs) possess anticancer and chemopreventive properties against
cancer in various organs, including the colorectum and liver. GTCs have also been known to exert anti-
obesity,
antidiabetic, and anti-inflammatory effects, indicating that GTCs might be useful for the prevention of
obesity-associated colorectal and liver
carcinogenesis. Further,
branched-chain amino acids (BCAA), which improve
protein malnutrition and prevent progressive
hepatic failure in patients with chronic
liver diseases, might be also effective for the suppression of
obesity-related
carcinogenesis because oral supplementation with BCAA reduces the risk of HCC in obese cirrhotic patients. BCAA shows these beneficial effects because they can improve
insulin resistance. Here, we review the detailed relationship between metabolic abnormalities and the development of CRC and HCC. We also review evidence, especially that based on our basic and clinical research using GTCs and BCAA, which indicates that targeting metabolic abnormalities by either
pharmaceutical or nutritional intervention may be an effective strategy to prevent the development of CRC and HCC in obese individuals.