Interviews:

The metabolic syndrome, otherwise known as syndrome X, was defined as a clustering of cardiovascular risk factors which include hyperinsulinemia and hypertension, even though BMI is sometimes used to define obesity, some have defined metabolic syndrome using central obesity as a major criterion of metabolic syndrome.⁶³ Despite the importance of waist circumference definition, many people are diagnosed with metabolic syndrome without a corresponding increased waist circumference or are not obese.⁶⁴

The abdominal subcutaneous tissue closely correlates with insulin resistance in essential hypertensive patients.⁶⁵ Although BMI is sometimes used to define obesity, visceral adiposity may be more important in defining the relation between blood pressure and obesity.⁶⁶ Also adiposity increases the likelihood of coexisting metabolic syndrome in people with hypertension. This syndrome is important because it identifies individuals at high risk of developing hypertension.

In a study in which MRI was used to define the quantity of adiposity in untreated hypertensive men, fat was seen to accumulate preferentially abdominally and intra-thoracically, and this visceral adiposity was found to relate quantitatively to the height of blood pressure.⁶⁷

2.10 LIFESTYLE RISK FACTORS FOR HYPERTENSION

i. Dietary factors

Dietary approach to stop hypertension (DASH) study

The findings of a study which was conducted in a representative sample of an Iranian population suggested that lifestyle habits can be improved by a community based lifestyle intervention programme even in developing country setting.⁶⁷ After the programme, beneficial changes were noted in diet and physical activity but no substantial behavioural changes were seen among those that smoked particularly among women. Total lifestyle scores and the percentage of individuals with a healthy lifestyle increased significantly in the intervention area.⁶⁷

Changes in dietary patterns have been considered the most verifiable reasons for the rising blood pressures in the general population of the Western industrialized countries when compared to those in primitive communities. The World Health Organisation-Cooperative Cardiovascular Disease and Alimentary Comparison (WHO-CARDIAC) study which was a multi-centre epidemiologic research, both the systolic and diastolic blood pressures correlated with salt intake measured by 24 hour urinary sodium excretion.⁶⁹ It has become generally accepted that it is not just sodium but the relative proportions of sodium and potassium intakes that affect blood pressures in both man and animals. Whereas processed food is rich in sodium and poor in potassium, natural food from fruits and vegetables are rich in potassium but poor in sodium, increase consumption of foods rich in potassium such as bananas reduces the risk of developing hypertension and enhances blood pressure control.³⁸ Those observations are therefore thought to explain the fact that hypertension

affects less than 1% of primitive communities but a third of the population in the western industrialized countries.⁷⁰

Unhealthy diet is a major risk factor for chronic diseases like hypertension. The recommendation for the general population and individuals include; the maintenance of a normal weight with a BMI of 18.5 to 24.9, the attainment of energy balance and a healthy weight. This also includes Individuals limiting their energy intake and aim to shift fat consumption away from saturated fats to unsaturated fats. Increase in the consumption of fruits and vegetable, and legumes, whole grains and nuts have been recommended. The intake of free sugars and salt (sodium) should be limited.

Ii. Salt

INTERSALT

The INTERSALT study was an international epidemiologic survey of 10,079 men and women aged 20-59 from 32 countries. It supported earlier reports that high salt intake is a modifiable risk factor for high blood pressure.⁷¹

The consumption of salt from all sources should be reduced and dietary salt as much as is possible should be iodised. Up to 2.7million lives could be saved annually with sufficient fruit and vegetable consumption.⁵ Evidence shows that reduced sodium consumption lowers blood pressure and can prevent hypertension. Daily requirement of dietary sodium for normal body function is less than 10 mmol per day. This amount is far less than average daily intake in many countries.⁷²

iii. Alcohol

The chronic ingestion of excessive amounts of alcohol has been associated with the risk of hypertension in both men and women. In their analysis of the large database of the community based Atherosclerosis Risk in Community (ARIC) study the author reported a relationship between alcohol consumption and the risk of incident hypertension.⁷² This association of alcohol intake and the risk of hypertension have also been reported from a study of approximately 40,000 participants drawn from the Women Health Study (WHS) and the Physician Health Study (PHS).⁷³ Limiting alcoholic beverages to 2 drinks a day for men and 1 drink a day for women has been recommended.⁷⁴

iv Smoking

In 2007, CDC estimated 19.8 % (43.4million) of U.S adults were current cigarette smokers.⁷⁵ Prevention of initiation and smoking cessation at all ages is beneficial in reducing morbidity and mortality.

vi Physical activity

There is a relationship between inactivity and non-communicable diseases. Physical inactivity is a risk factor for increased blood pressure; overall, 1.9million deaths are attributable to physical inactivity.⁶⁶ Exercising such as brisk walking which raises ones heart rate for at least 30 minutes a day on most days or preferably every day of the week is known to prevent many non communicable diseases such as hypertension.⁷⁶ Strenuous physical activity but not light exercises have been shown to prevent the risk of hypertension. In a study of approximately 15,000 Harvard alumni, risk from lack of exercise was reported to be independent of body mass index and family history of hypertension.⁷⁷ In yet another large

study of both whites and blacks aged 18 to 30 years and followed up for up to 15 years, the risk of incident hypertension was more in the less physically active persons than their more active counterparts.^{78, 79}

Vii Trial of hypertension prevention (TOHP)

In a trial of hypertension prevention, participants were randomised into lifestyle intervention groups; the Trials of Hypertension Prevention (TOHP), the design was a 2x2 factorial, with intervention groups of weight loss alone, sodium reduction alone, a combination of weight loss and sodium reduction, and a usual care group⁸⁰. A total of 2382 participants were randomised into the trial. After 36 months, they found that the pooled active sodium groups experienced a net decrease in sodium excretion of 33mmol/24 hour, with no significant blood pressure reduction.⁸⁰ The sodium reduction alone group experienced a net 40mmol/24 h reduction in sodium excretion with corresponding blood pressure reductions of 1.2/0.7 mmHg compared with usual care, which was significant (p=0.02) for systolic blood pressure only. The sodium reduction only intervention resulted in lower incidence of hypertension, with a relative risk of 0.82 (p=0.05) compared with usual care.⁸⁰

CHAPTER 3