By Dr Ananya Mandal, MD
High blood pressure (hypertension) is a common health problem plaguing millions worldwide. Obesity is also an important public health problem with its high prevalence and concomitant risks of heart disease, diabetes and kidney disorders.
Studies have shown that by 2025 an estimated 1.56 billion people worldwide would suffer from high blood pressure. This is a 60% rise from the numbers in 2000. This predicts a cardiovascular disease epidemic since high blood pressure affects the heart as well as several blood vessels leading to serious end organ damage like kidney disease and eye damage.
Obesity and high blood pressure
Studies have shown that the rise of high blood pressure sufferers is seen in conjunction with a dramatic increase in the prevalence of overweight and obesity.
According to the International Obesity Task Force at present at least 1.1 billion adults are overweight, including 312 million who are obese.
The rise has shown similar upward trends in United States as well as Europe. In England, 66% of men and 55% of women are either overweight or obese.
Obesity and heart conditions
Obesity has been linked to several heart conditions including coronary heart disease, heart failure and type 2 diabetes mellitus along with high blood pressure.
Roughly 60% of all the diabetics have increased body weight. Further abdominal obesity is responsible for a higher risk due to the high rate of flow of the fatty acids and hormones into the liver from the abdominal fat deposits.
Accordingly waist circumference and waist-to-hip ratio are surrogate markers for abdominal or visceral obesity and can predict heart attacks, heart disease and diabetes more accurately than body mass index (BMI).
Apart from the link between obesity and high blood pressure, the concomitant occurrence of both these conditions together also poses a considerable economic burden on societies.
Data from the latest National Health and Nutrition Examination Survey (NHANES) for 1999–2000 reveals that although blood pressure control rates have become much better since 1988 from 25% to 31%, they are still low. This has led to 39,702 cardiovascular events, 8734 cardiovascular disease deaths, and 964 million dollars in direct medical expenditures in the United States. In Europe the figures are 1.26 billion Euros due to lack of adequate pressure control.
Obesity and hypertension
Obesity is a major cause of hypertension. This risk has been estimated by the Framingham Heart Study that suggests that approximately 78% of the hypertension cases in men and 65% in women can be directly attributed to obesity.
Blood pressure and BMI
After screening nearly 1 million Americans, a direct relation between blood pressure and BMI has been noted. The NHANES reports also show a direct relation between BMI and systolic and diastolic blood pressures. This relationship holds true for obese children and adolescents as well.
High blood pressure and fat distribution
Further the connection with high blood pressure is also present with body fat distribution in obesity. Abdominal obesity has been linked to hypertension in studies.
The Normative Aging Study for example showed that in men over 18 years of the study hypertension risk increased approximately threefold with a one-unit change in the abdominal circumference/hip breadth ratio.
The Framingham Heart Study revealed that a 5% weight gain increases hypertension risk by 30% in a 4-year time period. However weight loss reduces both systolic and diastolic blood pressures.
Obesity, hypertension and the kidneys
It has been seen that in obese patients with hypertension, there is an increased absorption of sodium from the kidney and an increase in blood volume. This could be due to the activated sympathetic nervous system or the renin–angiotensin system and high pressures within the kidney.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)