Effect of Dietary Phytochemicals in Obesity and Cancer

Phytochemicals are the plant-derived secondary metabolites that possess biological activity. Active phytochemicals are widely distributed in plant genera and occurred naturally in the diets of fruits, vegetables, grains, and plants based products. Dietary phytochemicals are classified based on their chemical structure like polyphenols, alkaloids, carotenoids, and nitrogen-sulfur containing compounds. Plants protect themselves from external threats and environmental agents like UV-rays and free radicals producer by producing active phytochemicals. The occurrence of these active phytochemicals in our diet may be an indication to protect us from free radicals by neutralizing harmful reactive radicals. Cumulative in vitro and in vivo studies demonstrated that these phytochemicals possess additional activities (anti-inflammation, anti-microbial, anticancer, and antidiabetic) except antioxidant activity (Vauzour et al. 2010). Therefore, phytochemicals and their derivatives attract the attention of scientists and researchers and provide a valuable contribution to natural drug discovery programs. Phytochemicals also possess medicinal properties in the context of their relevance to human disease (such as obesity, diabetes, and cancer) prevention and cure. Obesity is referred to as an accumulation of adipose tissues that impair health. In 2016, it was estimated that 1.9 billion adults were overweight and 650 million out of 1.9 billion overweight were obese. Obesity likely causes more death than non-obese. Body mass index (BMI) is used to classify overweight and obesity. Obesity is a major risk factor for diabetes and cancer. Increased BMI is highly associated with diabetes. It is well known that gain of weight and body mass are the main causes of more incidence of diabetes (type1 and type2 diabetes). In obese persons, an amount of glycerol, free fatty acids, steroid hormones, and pro-inflammatory cytokines are linked with the development of insulin resistance. Obesity enhanced cancer progression, because of a large accumulation of adipose tissues with dysregulated function, adiposity death, and chronic inflammation. Therefore, in obese individuals, inflammation has played a central role in the progression of cancer. Diabetes (commonly known as diabetes mellitus) is a metabolic disease and causes the seventh leading source of death worldwide. To date, diabetes causes a total of 422 million cases and 1.6 million deaths per year as reported by world health organization (WHO, Obesity and overweight. https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight, 2020). Diabetes mellitus is characterized by increased levels of blood glucose and decreased production and function of insulin hormone (Maritim et al. 2003). Cancer is the second largest cause of death worldwide which causes 9.6 million deaths in 2018. The most commonly occurring cancers are lung, breast, colorectal, prostate, skin, and stomach cancers. Various studies have reported that oxidative stress induced DNA damages, elevated amounts of free radicals, and low levels of antioxidants are associated with diabetes and cancer (Matough et al. 2012; Chikara et al. 2018). Many dietary phytochemicals of different groups such as flavonoids, isoflavonoids, lignans, propenyl-phenols, and alkaloids possess free radicals scavenging (antioxidant activity) capabilities which suppress the oxidative stress (Chikara et al. 2018). Besides this, dietary phytochemicals have exerted numerous other biological activities to fight against several other human diseases including diabetes mellitus and cancers (Kushwaha et al. 2018). The use of phytochemicals in the treatment and prevention of different types of human diseases is very effective, safe, and cheap. Many phytochemicals having medicinal properties are being used alone and in combinations with antidiabetic and anticancer drugs to treat the ailments (Ezuruike and Prieto, 2014).