
Nonpharmacological Intervention in the Elderly
(TONE) showed that a 40 mmol day
1
reduction is
accompanied by significant reductions in blood
pressure (5.3/3.4 mmHg). This modest salt restric-
tion can be achieved by not adding salt at the table
and avoiding foods that are high in sodium content
(e.g., preserved food). Saltiness is a rather crude
taste and is used by the industry to enhance the
palatability of food cheaply and to boost the sale
of beverages. Historically, salt was needed to pre-
serve food for the winter months but nowadays,
refrigeration renders this unnecessary. Fresh food is
usually low in salt content and its flavors are better
appreciated when not too much salt has been added
in cooking.
0007 Carefully controlled clinical studies have demon-
strated a dose-dependent relationship between
dietary salt intake and blood pressure, although trials
of salt restriction do not always show a useful re-
duction in blood pressure due to their various trial
designs. Salt restriction is particularly important
when the patient is treated with an angiotensin-
converting enzyme inhibitor (ACEI) or an angiotensin
II antagonist (sartan). The efficacy of these drugs is
diminished in the presence of high salt intake that
suppress the renin–angiotensin system.
Potassium
0008 In contrast to sodium, potassium is less tightly regu-
lated physiologically. In diuretic therapy, the renal
tubules will conserve sodium at the expense of
potassium. Plasma potassium concentration is also
linked to acid–base balance. Nevertheless, potassium
is also closely associated with blood pressure. Cross-
sectional studies in many countries worldwide had
identified an inverse relationship between blood pres-
sure and various measures of serum, urine, total body
and dietary potassium. Low potassium intake may
also underlie the high incidence and prevalence of
hypertension in blacks and the elderly. Potassium
supplementation alone will decrease blood pressure
slightly. The effect is more pronounced in hyperten-
sives than normotensives, in blacks than in whites,
and in those with high sodium intake. In reality,
higher potassium intake is usually associated with a
diet rich in fruit and vegetables. Such a diet will in
itself be conducive to a lower blood pressure, so one
cannot always disentangle the components of a
‘healthy diet’ which are actively antihypertensive.
High sodium intake and low potassium intake is a
common scenario amongst hypertensive patients.
Therefore, sodium and potassium should be con-
sidered jointly in our dietary recommendations.
For example, using a salt substitute that contains
potassium chloride increases potassium intake whilst
reducing sodium intake.
Calcium
0009The relationship between calcium and hypertension
is controversial. Dietary intake of calcium tends
to be lower in hypertensives and calcium supple-
mentation is associated with a modest reduction in
blood pressure. A metaanalysis of 23 observational
studies showed an inverse association between
blood pressure and dietary calcium intake. The effect
size was however small and heterogeneous across
studies. Metaanalysis of randomized trials of calcium
supplementation showed that systolic blood
pressure is reduced by around 1 mmHg. Although it
is possible that certain subgroups may be more sensi-
tive to the effects of calcium, it is certainly not the
major factor in the pathogenesis of hypertension,
despite the recent identification of a parathyroid
hypertensive factor. Therefore, calcium supplementa-
tion, though desirable for other reasons, is not
currently recommended as an efficacious means of
treating hypertension.
Fat
0010The relationship between lipids and coronary heart
disease is now proven beyond doubt by epidemi-
ological studies and large-scale trials of lipid-
lowering drugs (statins) that reduce coronary events.
Reduction in cholesterol by pharmacological means
may not lower blood pressure, but should be viewed
in the context of the overall reduction of cardiovas-
cular risk and the reduction of complications of
hypertension such as myocardial infarction. Hyper-
tension and dyslipidemia are independent cardio-
vascular risk factors and, when they are both present
in the same person, the cardiovascular risk is aug-
mented. Therefore, it makes sense to address both
risk factors. Nonpharmacological means of lipid
lowering through diet and exercise is likely to have
a beneficial effect on blood pressure in addition to
improving the cardiovascular risk profile. The
DASH study suggested that a healthy diet based on
less fat and more fruit and vegetables reduces blood
pressure, although precisely which component of the
DASH diet lowers blood pressure remains to be
elucidated.
0011The effects of saturated, monosaturated, and poly-
unsaturated fatty acids and carbohydrates have been
studied in many clinical trials. Omega-3 unsaturated
fatty acids (fish oils) reduce blood pressure but a large
intake is needed, so this is not a practical treatment
for hypertension.
3196 HYPERTENSION/Hypertension and Diet