Systems engineering investigation into the effects of different lifestyle factors on chronic diseases

Abstract

Background: Both coronary heart disease (CHD) and breast cancer (BC) are multifactorial diseases with complex aetiologies. Various research publications suggest that inflammation is the link between several chronic illnesses such as BC and CHD. Inflammation is influenced by several different lifestyle factors, such as excessive food intake, alcohol consumption, stress, smoking, exercise and fibre intake. The systemic effects of each of these lifestyles on CHD and BC have yet to be integrated. It also is unclear which of these factors has the largest impact on the different chronic diseases, as they are quantified in different units. However, it is known that blood glucose (BG) levels are directly linked to inflammation and, therefore, to CHD and BC. Aim: To develop a comprehensive model to account for the variety of systemic influences on CHD and BC, with an emphasis on lifestyles and the inflammatory state. The interconnected nature of the lifestyle effects and of inflammatory pathways necessitates the development of a unifying system property, chosen to be BG. Method: A common unit known as ETS (equivalent teaspoons of sugar) was developed for each of the above lifestyle factors, quantifying each factor in terms of its BG (glycaemic) effect. Data were collected from various published meta-studies and transformed using the eETSmodel. A systems engineering approach was followed to investigate the numerous cross-couplings that exist between the CHD and BC pathogenetic factors and lifestyle effects. This resulted in graphical representations illustrating the effects the different lifestyle factors have on inflammation, as well as the relative risk (RR) for BC and CHD. Results: Stress, excessive food intake and smoking contribute to increased BG levels. High BG levels are associated with increased levels of inflammation, RR for CHD and RR for BC. Psychological stress is the largest contributor to inflammation and the risk for CHD and BC. It increased hs-CRP (an important biomarker for CHD) values four-fold, RR for CHD 4.4 fold and RR for BC 2.5 fold. Dietary fibre intake, low to moderate intensity exercise and moderate alcohol consumption are inversely associated BG levels. Lower BG levels are related to a decrease in inflammation and risk for BC and CHD. Low to moderate exercise had the strongest anti-inflammatory effect and reduced BC risk approximately two-fold. Moderate alcohol consumption plays an important role in the reduction of RR for CHD. Conclusion: A systems engineering-based analysis of CHD and BC reveals the interconnected, systemic nature of these diseases. Despite their complex aetiologies, both diseases show the pivotal role of BG in disease progression or proliferation. This highlights the importance of glucose controlled therapeutics and lifestyle interventions in managing CHD and BC. Key words: Blood glucose (BG), chronic diseases, coronary heart disease (CHD), breast cancer (BC), inflammation, lifestyle factors, cigarette smoking, psychological stress, alcohol, dietary fibre, excessive food intake, physical exercise, equivalent teaspoons sugar (), relative risk (RR), C-reactive protein (CRP), grams (g) of fibre, grams (g) of ethanol , cigarettes per day, Metabolic Equivalent (METs), Glycaemic Load (GL), insulin sensitivity, blood pressure, blood viscosity and insulin resistance