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ENDOCRINOLOGY FOCUS OBESITY
Nutrition, Obesity and Cancer Risk Written by Kathleen A.J. Mitchelson1 and Helen M. Roche1,2 UCD Conway Institute, Nutrigenomics Research Group and Institute of Food and Health, University College Dublin, Dublin, Ireland and 2Institute for Global Food Security, Queen’s University Belfast, Belfast, Northern Ireland 1
Global obesity rates are continuously increasing, having tripled in the last fifty years. Obesity is linked with the occurrence of several co-morbidities including cardiovascular disease, insulin resistance and type 2 diabetes. More recently, obesity has emerged as a major determinate of some cancers. There are at least 13 types of cancer which have a higher incidence rate in those who are overweight or obese, including breast, oesophageal and colorectal cancer. Additionally, individuals Figure 1: High-fat diet induced obesity with increased visceral adipose tissue. Diets predominantly composed of saturated fats (SFA) versus monounsaturated fats (MUFA) differ in adipose tissue profiles following a high-fat diet.
who are heavier, with a higher body mass index (BMI) at cancer diagnosis have a higher risk of developing a second, unrelated cancer. Classic features of obesity include metabolic disease, characterised by high blood glucose levels, insulin resistance and persistent low grade inflammation, collectively termed ‘metabolic inflammation’. Poor diet is a well-known driver of metabolic inflammation. Dietary elements and their digested components either increase or decrease inflammation. However, we are only just beginning to understand how the foods we eat might influence cancer risk. We need to better understand if/how
High-fat diet with Saturated Fat High Metabolic Disease Risk High Cancer Risk
different dietary ingredients can regulate metabolic inflammation when a person develops obesity and consumes a high-fat diet (HFD) within the context of cancer. This will allow for a more complete understanding of the role that obesity has on metabolic inflammation in cancer pathogenesis. OBESITY, INFLAMMATION AND GASTROINTESTINAL CANCER How does obesity and adipose effect inflammation? The classical hallmark of obesity is the increase in adipose tissue mass. Adipose tissue is where we store excess energy as fat cells. Although adipose tissue was initially thought to just store excess
energy, it is now appreciated to have important endocrine functions, secreting cytokines and adipokines which communicate with other cells effecting their behaviour. Adipose tissue is primarily comprised of fat-storing cells called adipocytes, which are surrounded by other cell types that play important roles in human health called the stromal vascular fraction (SVF). SVF is composed of a heterogenous collection of cells including fibroblasts, pre-adipocytes, endothelial cells and immune cells among others. These cells help adipose tissue to communicate with other organs by influencing the signals released. In obesity, the fat cells increase in number and expand in size to store excess energy.
High-fat diet with Monounsaturated Fat Lower Metabolic Disease Risk Lower Cancer Risk?
↑ adipocyte size (hypertrophy) ↓ ↓ adipocyte number (hyperplasia) ↑ ↑ pro-inflammatory macrophages ↓ ↑ pro-inflammatory cytokines ↓ ↑ insulin levels ↓ ↑ hormones↓ ↑ growth factors ↓ ↑ inflammation ↓ ↑ cancer cell production ↓?
↑/↓ Effect of HFD - SFA ↑/↓ Effect of HFD - MUFA
Figure 1 High-fat diet induced obesity with increased visceral adipose tissue Diets composed of saturated fats (SFA) versus monounsaturated JULY 2022 • predominantly HPN | HOSPITALPROFESSIONALNEWS.IE
