Nutrition, Genetics and Cancer

Studies indicate that diet-related cancers are becoming more frequent every day. The types and amounts of foods and when we eat them matter. Scientific evidence now establishes that certain diets, such as Mediterranean cuisine, reduce cancer risk, but the many interacting factors make this field difficult to study. Lifestyle is considered the greatest contributor to cancer risk. It is therefore claimed that more than half of cancers below age 65 can be prevented.

Which Foods, in What Amounts and Over What Period Cause Cancer?

There is currently no single or simple answer. While some risk factors for diabetes and cardiovascular disease are clearly defined, those for many cancers are not. High blood glucose is strongly associated with diabetes, and elevated blood lipids with cardiovascular disease. New cancer risk factors are identified daily and suspected ones clarified. For example, processed meat is now clearly established to increase colon cancer risk. Its consumption is a risk factor, a marker indicating future colorectal cancer likelihood among heavy consumers. Better understanding of cancer biology and rapidly developing genomic applications reveal new markers.

An Overview of Cancer Biology from a Nutritional Perspective – Why Do Tumors Develop?

The underlying cause of all cancers is abnormal gene expression after genetic damage. Mutations, chromosome damage, shortened telomeres (DNA ends), abnormal epigenetic factors (changes in gene expression without DNA structural change) and other DNA-damaging conditions cause cellular changes. Cells attempt to minimize damage by repairing it, trapping free oxygen radicals and neutralizing mutagens (substances damaging DNA). If damage is irreparable, cells normally die through apoptosis. Tumors resist oxygen deprivation better than normal cells, form new vessels and can migrate elsewhere (metastasis). As we age, DNA repair mechanisms deteriorate and damage accumulates. Loss of tumor suppressor function and gain of oncogene function are important in tumor development. Environmental factors such as diet and lifestyle, together with genetic makeup, contribute to differences in cancer risk between individuals.

The Genome–Diet Relationship

Passing a damaged DNA copy to the next generation is the basis of hereditary cancers . For example, mutations in BRCA1 and 2 cause hereditary breast cancer, but account for %10-12 of these cancer cases. Polymorphisms also matter in cancer. Polymorphism means different forms of a gene. It may occur in one or several genes simultaneously. Single-gene polymorphisms matter because under particular conditions they can cause cancer. For example, people with the C677T polymorphism in MTHFR develop bowel cancer when folate intake decreases and even small amounts of alcohol are consumed. In people carrying a polymorphism in the acetylase-encoding gene, heavy consumption of red meat cooked at high temperatures increases gene activity and triggers bowel cancer. This has shown that genes do not act alone, and environmental factors and diet affect their functioning as a demonstrated relationship. Changing foods and nutritional values within the diet is thought to allow improvement. Plant-rich diets, particularly fruit and vegetables, reduce cancer risk. The anticancer properties of plant phytochemicals are under extensive investigation, such as broccoli reducing head and neck cancer risk. Identifying individual genetic characteristics, calculating their relationship with environmental factors and determining cancer risk are important future goals. The gene-diet relationship is gaining importance in cancer prevention. A new field has emerged in this context: Nutrigenomics!