• All people who are having their blood pressure measured should be provided with lifestyle advice in order to facilitate blood pressure reduction or prevent hypertension developing in future years.
  
• Patients with blood pressures that are above average for their age but not high enough to warrant drug therapy should be reviewed about once per year for reinforcement of lifestyle advice.
  
• Patients who are overweight or obese should be advised on the benefits of weight reduction on blood pressure and referred for expert dietetic advice.
  
• Patients should be questioned on the amount of exercise they take. Those who take little exercise should be advised to increase gradually by avoiding lifts and escalators where possible and regularly walking about 1 mile/day. Vigorous static or dynamic exercise should not be recommended.
  
• The salt intake of all patients should be assessed by detailed questioning. Patients should be warned on the hazards of a high salt intake and the proven benefits of reducing salt intake. Dietary salt can be reduced by avoiding ‘junk’ or convenience foods and salty processed foods and snacks. Expert dietetic advice should be recommended. Do not recommend salt substitutes.
  
• Alcohol intake should be assessed; those who consume more than 14 units per day (women) or 21 units per day (men) should be advised to reduce
  
• All smokers should be advised on the dangers of this habit and should be referred to local antismoking facilities.
  
• Do not recommend dietary supplements of potassium, magnesium or calcium.
  
• Patients should be advised that yoga or relaxation therapies are of little value.
  
• Advise patients to enter the Blood Pressure UK website for more information (see chapter 7).

Obesity and weight reduction

Obesity and hypertension are closely related; the mechanisms of this relationship are complex. Firstly, there is a tendency to over-read blood pressure with an upper arm cuff. This source of error can be reduced by using larger blood pressure cuffs when the arm circumference exceeds 35 mm. Other true mechanisms include a higher salt intake associate with obesity, insulin resistance, increased sympathetic tone and sodium and water retention. Obesity is also closely related to obstructive sleep apnoea (OSA), which also causes a rise in blood pressure.

There is increasing anxiety about the rising prevalence of overweight (BMI 25–30) and obesity (BMI ≥ 30) in the general population. In some populations in the developed countries, obesity is seen in 30% of adults. Clearly, therefore, obesity must be seen as a public health issue, which needs to be solved by public heath means, if necessary with legislation.

At I clinical level, weight reduction does cause a significant fall in both systolic and diastolic blood pressure. Most of these controlled trials have been relatively short term and have required a lot of effort by the research trialists (Figure 8.1). Sadly some of the reductions in weight achieved in the short term have not been maintained on a longer term basis. Taking into account all studies, a simple rule of thumb for patients is that if they can reduce their weight by 1 kg (roughly 2 lb) the diastolic pressure will fall by about 1 mm Hg; a 5 kg (roughly 10 lb) reduction will reduce diastolic pressure by 5 mm Hg and so on.

There is evidence that dietary advice and support provided by nutritionalists and dietitians is more effective than advice by a doctor in a routine clinical setting. Technical advice, information of healthy versus unhealthy foods and their availability, together with information leaflets and Internet access to Blood Pressure UK may also prove beneficial.

Weight reduction also has beneficial effects on other risk factors associated with hypertension, including insulin resistance, type 2 diabetes mellitus, dyslipidaemia and left ventricular hypertrophy. The blood pressure-reducing effect of weight reduction should be complemented by an increase in physical exercise and a reduction in the intake of salt and alcohol.

Salt intake and salt restriction

Many studies confirm a clear and causal relation between dietary intake of salt and blood pressure. Conversely, a strategy of salt restriction to <100 mmol/day (<6 g/day) significantly reduces blood pressure. A reduction in salt intake from an average of 10 g/day (about two teaspoons) to 5 g/day can result in an average reduction in blood pressure of 5/2 mm Hg (Figure 8.2). Reductions in salt intake can result in larger decreases in blood pressure in the elderly, African-Caribbean people (who are more salt sensitive), and those with higher initial blood pressures. On average, one-third of such patients who reduce their intake of salt will achieve a reduction in blood pressure of 5/5 mm Hg.