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Hypertension
L. Kathleen Maban and Sylvia Escott-Stump:Food,
Nutrition & Diet Therapy, 9th
告報者：劉佩姎 營養師
日期：93/03/25
Hypertension
• Hypertension is the most common
public health problem in developed
countries.
• Called Silent Killer
• No cure is available, but prevention
and management decrease the
incidence of hypertension and disease
sequelae.
Classification
• Essential or Primary hypertension: 90
~ 95% the cause can’t be determined,
therefore treatment is nonspecific.
• Secondary hypertension: caused by
another disease, ex: renal or
endocrine
Definition
• SBP (systolic blood pressure)  140
mmHg and/or DBP (diastolic blood
pressure)  90 mmHg
Joint National Committee on Detection,
Evaluation, and Treatment of High
Blood Pressure
Table 24-1
Classification of Blood Pressure for Adult over Age 18*
Category
Systolic, mmHg
Diastolic, mmHg
＜130
＜85
130~139
85~89
Stage 1 (mild)
140~159
90~99
Stage 2 (moderate)
160~179
100~109
Stage 3 (severe)
180~209
110~119
 210
 120
Normal
High normal
Hypertension
Stage 4 (very severe)
Prevalence
Table 24-2
Prevalence on hypertension by age
Age
% Hypertension
18~29
4
30~39
11
40~49
21
50~59
44
60~69
54
70~79
64
80 +
65
Morbidity and Mortality
Table 24-3
Manifestation of Target Organ Disease
Organ System
Cardiac
Manifestations
Clinical, electrocardiographic, or radiologic
evidence of coronary artery disease; left
ventricular hypertension; left ventricular
function or cardiac failure
Cerebrovascular Transient ischemic attack or stroke
Peripheral
Absence of 1 or more pulse in extremities
(except for dorslis pedis) with or without
intermittent claudicating; aneurysm
Renal
Serum creatinine
Retinopathy
Hemorrhages or exudates, with or without
ppapilledema
＞ 130 mol/L (1.5 mg/dL);
Protenuria (1 + or greater); microalbuminuria
Table 24-4
Factor Indicating an adverse prognosis in hypertension
Black race
Youth
Male
Persistent diastolic pressure ＞ 115 mmHg
Smoking
Diabetes mellitus
Hypercholesterolemia
Obesity
Excessive alcohol intake
Evidence of target organ disease
Physiology
• Blood pressure levels: a function cardiac
output mutipied by peripheral resistance
(the resistance in blood vessels to the flow
of blood)
• Diameter of blood vessels
• Sympathetic nerve system ( for shortterm control)
• Kidney (for long-term control)
Blood Pressure fail
↓
Sympathetic nerve system
↓
Norepinephrin
↓
Act on small arteries and arterioles
↓
↑ peripheral resistance
↓
↑Blood Pressure
Decreased arterial pressure
↓
Renin (Kidney)
↓
Renin substrate
Angiotensin I
(Plasma protein)
Coverting Enzyme (Lung)
Angiotensin II
Angiotensinase
(Inactived)
Renal retension
Vasoconstriction
of salt and water
Increased arteial pressure
• Regulatory mechanism falter, hypertension
develop.
• Neurohormonal and intrarenal
• Peripheral resistance↑→ left ventricle of heart
increase effort in pumping blood → left
ventricular hypertrophy → congestive f=heart
failure
Primary prevention
• A population strategy: lower the
blood pressure in general population
• A targeted strategy: direct
intervention to lower blood pressure
at individuals who are at greatest risk
of developing hypertension.
Table 24-5
Factor influencing the development of hypertension
High-normal blood pressure
Family history of hypertension
African-American ancestry
Overweight
Excessive salt consumption
Physical inactivity
Alcohol consumption
• Genetic predisposition to H/N interacts
Obesity
Life-style
Dietary components
Diet-related factors influencing
development of hypertension
• Changing four modifiable factors has
documented efficacy in the primary
prevention of hypertension.
-Overweight
-High salt intake
-Alcohol consumption
-Physical inactivity
Overweight
• Two to six times higher in overweight than
in normal-weight individuals
• Higher prevalence rates are seen in
Mexican-Americans and non-Hispanic black
women
• Greater fluctuation in weight
• 50~59 yr non-Hispanic white women
• 30~39 yr non-Hispanic black and MexicanAmerican women
• 20~34 yr weight gaining more than 30 lb in
a 10 years
Factor associated
• Low educational attainment
• Low socioeconomic status
Framingham Study
• Increase related weight of 10% was
predictive of a 7 mmHg rise in blood
pressure
• Inuslin resistance
• hyperinsulinemia
• activation of sympathetic nervous and
renin-angiotensin system
• physical changes in the kidney
Energy intake↑
↓
plasma insulin ↑
↓
increase renal sodium reabsorption
↓
blood pressure ↑
BMI
Early identification of children as potential
hypertensive
Excess consumption of
sodium Chloride
• Consuming 100 mEq/day or less or
sodium was associated with a 2.2
mmHg fall in SBP
• The rise in SBP seen with aging over
30 years would be 9 mmHg less and
the rise in DBP 4.5 mmHg less if the
average sodium intake were lowered
by 100 mEq/day
Alcohol Consumption
• Three drinks per days (a total of 3 oz
of alcohol) is the threshold for
raising blood pressure and is
associated with a 3 mmHg rise
Not more than 1 oz of ethanol/day, which is
equal to 2oz of 100-proof whiskey, or 24 oz
of beer
Exercise
• Physical activity produces a fall in
SBP and DBP of about 6 to 7 mmHg
Moderate physical activity defined as
30 to 45 minutes of brisk walking,
three to five times per week
Other Dietary Factors
•
•
•
•
Potassium
Calcium
Magnesium
Lipids
Potassium
• Inversely related
• higher potassium intake→lower blood
pressure
• reduces peripheral vascular
resistance by direct arteriolar
dilatation, increase loss of water and
sodium from the body
• Sodium: potassium ratio of the diet is
related to BP
• Clinical trails with potassium
supplement yielded mixed results
• Dietary potassium is an adjunct to
weight control and reduced sodium
consumption for prevent of H/N
• Na:K ratio of 1.0 is the goal
Calcium
• African-American and women
• Clinical trials showed minimal
hypotensive effects of high dietary
calcium intake from foods or
supplement .
• Calcium from dietary sources to meet
the RDA is recommended
Magnesium
• Mg is a potent inhibitor of vascular smooth
muscle contraction and may play a role in
blood pressure regulation as a vasodilator.
• Most clinical studies, Mg supplement has
been ineffective in altering blood pressure,
possible because of the confounding
effects of antihypertensive medications
and the short duration of the studies.
• Adequate data are lacking to recommend
routine supplement with magnesium to
prevent hypertension
lipids
• PUFA
Precursors of prostaglandins
-affect renal sodium excretion
-relax vascular musculature
• Large doses of fish oils (50 ml daily
with 15g -3 PUFA) have lowered BP
in mildly hypertensive men
Knapp and Fitzgerald, 1989
• Smaller doses (6~20g fish oil/daily)
had no effect on BP in hypertensive
or normotensive subjects
Lofgren, 1993; Sack, 1994
Small doses are hazardous with
respect to their effect on bleeding
time, weight gain, glycemic control
and LDL-cholesterol
-3 FA is not recommended for
preventing hypertension
Combination of risk factors
for cardiovascular disease
•
•
•
•
•
Medication
Management
Life-style modification
Weight management
Salt restriction
Medication
• Either raise blood pressure or
interfere with the effectiveness of
antihypertensive drugs, ex: oral
contraceptives, steroid, nonsteroidal,
anti-inflammatory agent, nasal
decongestants, other cold remedies,
appetite suppressants, tricyclic
antidepressants.
Management
• Goal: to reduce morbidity and
mortality from stroke, hypertensionassociated heart disease and renal
disease.
-increase to at least 50% the number
of people with hypertension whose BP
is less than 140/90.
Life-style modification
Table 24-7
Life-style modification for hypertension control
Lose weight if overweight
Limit alcohol intake to ≦ 1 oz/day of ethanol (24 oz beer, 8 oz
wine, or 2 oz of 100-proof whiskey)
Engage in aerobic exercise regular
Reduce salt intake to ＜ 6 g/day (100 mmole/day or 2.4 g of Na)
Maintain adequate dietary potassium, calcium and magnesium
Stop smoking
Reduce dietary saturated fat and cholesterol
Reduce total fat intake to no more than 30% of energy
Life-style modification
• Before drug therapy is begun, three
to six months of compliant life-style
modification should be tried.
• Life-style modification can’t
completely correct the BP, but they
will help increase the efficacy of
pharmacological agents and improve
other CVD risk factor.
Weight management
• The effectiveness of weight reduction has
been well documented in high in both mild
and severe hypertensives.
Lower blood pressure
Normalize Blood glucose and lipid
Synergistic effect with drug therapy
• Some stage 1 hypertensive achieve a
normal BP by weight loss alone.
Once weight is lost,
maintenance is critical
• High fat intake and a low level of
physical activity
• Weight maintenance goal:
(1)not to gain more than 10 to 15 lb
after age of 21
(2)not to have more than a 2 to 3 in.
Increase in waist circumference
after age 21
Salt Restriction
• Moderate salt restriction (6g of salt,
100 mEq or 2400 mg Na/day) is
recommended for treatment of
hypertension.
- Normalize Stage 1 hypertension
- Enhance drug therapy
• Unless congestive hear failure, severe
salt restrictions are not necessary.
Table 24-9
Sodium and potassium goals based on body weight
Weight
Sodium (mEq)
Potassium (mEq)
≦50.0
52.2
61.5
50.5-60.0
60.1
71.8
60.5-70.0
70.0
82.1
70.5-80.0
78.3
92.3
80.5-90.0
87.5
102.6
≧90.5
100.0
115.4
Thanks for your attention