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Advanced Nutrition
Diet and Arterial Hypertension
MargiAnne Isaia, MD MPH
DIET AND HYPERTENSION
SYSTEMIC HYPERTENSION
Definition
Systolic BP ≥ 140 mm Hg & Diastolic BP ≥ 90 mm Hg
Taking antihypertensive medications
Prevalence approx 18% of adults and 50-70% of elderly (>65) population
or BP ≥ 130/80 mm Hg in patients with Diabetes, Chronic Kidney Disease,
Coronary Artery Disease
or BP ≥ 120/80 mm Hg in patients with Heart Failure
Types
Essential hypertension (idiopathic, primary) 95% of cases
both systolic and diastolic pressure are elevated
Isolated systolic hypertension
only systolic pressure is elevated
2/3 of elderly population with hypertension
consequence of age-related sclerosis of large capacitance arteries
responds to sodium restriction and diuretics
DIET AND HYPERTENSION
JNC7* Classification of BP for adults aged 18 years and older
BP
Classification
Systolic
BP mm Hg
Diastolic
BP mm Hg
Lifestyle
Modification
Normal
< 120
≤ 80
Encourage
Prehypertension
120-139
or
80-89
Yes
Stage 1
Hypertension
Stage 2
Hypertension
140-159
or
90-99
Yes
≥ 160
or
≥ 100
Yes
and
JNC7* Joint National Committee on Prevention, Detection, Evaluation and Treatment of
High BP
In addition to classifying stages of HTN on the basis of average BP levels, clinicians should
specify presence or absence of target organ disease and additional risk factors
(this information is useful for risk assessment and treatment)
DIET AND HYPERTENSION
CARDIOVASCULAR RISK FACTORS/TARGET ORGAN DAMAGE
Major risk factors
Hypertension
Age (older than 55 for men, 65 for women)
Diabetes Mellitus
Elevated LDL-C
Low HDL-C
Glomerular Filtration Rate less than 60 ml/min
Microalbuminuria
Family history of premature heart disease (M < 55, F < 65)
Obesity ( BMI ≥ 30 kg/m2 , Waist Circumference M > 40 inches, F >35 inches
Physical inactivity
Smoking
Target organ damage
Heart
Brain
Left Ventricular Hypertrophy
Angina/prior Myocardial Infarction
Prior coronary revascularization
Heart Failure
Stroke or transient ischemic attack
Dementia
Chronic Kidney Disease
Peripheral Arterial Disease
Retinopathy
DIET AND HYPERTENSION
DETERMINANTS OF BLOOD PRESSURE
Arterial pressure is determined by
- cardiac output
amount of blood pumped by heart (vol/min) =
= stroke volume x heart rate
Stroke volume
cardiac contractility
vascular volume
Heart rate
- peripheral vascular resistance
- structural and functional changes in the vasculature
affect vascular resistance
- increased vascular resistance induces structural
and functional changes
Vascular resistance is determined by
- viscosity of blood
- width of vessels (constriction or dilation) controlled by
muscle tone in vessel wall
DIET AND HYPERTENSION
PRIMARY HYPERTENSION
Determinant Factors:
Sympathetic nervous system hyperactivity
tachycardia and elevated cardiac output
Abnormal cardiovascular or renal development
abnormal development of aortic elasticity or
reduced development of the micro vascular network
Renin-Angiotensin system activity
plasma Renin levels are classified in relation to dietary Na intake
or urinary Na excretion
Angiotensin II = potent vasoconstrictor and major
stimulant of Aldosterone release from adrenal gland
Defect in natriuresis
normal individuals increase Na excretion in response to increased
arterial pressure
Intracellular Sodium and Calcium
Na elevated in the cell may lead to increased intracellular Ca
this may explain the increase in vascular smooth muscle tone
characteristic of established hypertension
DIET AND HYPERTENSION
REGULATION OF BLOOD PRESSURE
Sympathetic nervous system – responds immediately
baroreceptors monitor blood pressure
- vasomotor center in the brain
- SNS innervated tissues contract or dilate vascular bed
Renin-angiotensin system
– retains Na and H2O to increase blood volume
- constricts blood vessels
- increases Aldosterone release
Kidneys- respond to renin-angiotensin system
Aldosterone and Antidiuretic hormone (ADH) involved
Homeostatic control of blood pressure
Short term: SNS, vasoconstriction, vasodilatation
Long term: fluid volume, RAA system
DIET AND HYPERTENSION
RISK FACTORS FOR HYPERTENSION
Identified by Epidemiology
Risk factors:
- Smoking
- Dyslipidemia
- Alcoholism
- Diabetes Mellitus
- Obesity
- Sedentary lifestyle
- Diet low in K and high in Na
DIET AND HYPERTENSION
EXCESS SODIUM INTAKE
AND SYSTEMIC HYPERTENSION
Epidemiological data
Primitive people who eat little or no Na have low incidence of HTN
and their BP does not rise with age
Yanomamo Indians of Northern Brazil – excrete 1 mmol Na/d
and have an average BP of 96/61 mm Hg
Primitive people who are free of HTN adopt modern lifestyle, including
increased intake of Na, their BP rises
Rural Kenyan men move to Nairobi
their Na excretion increases from 60 to 110 mmol/d
BP rises over a few months
DIET AND HYPERTENSION
LARGE POPULATION STUDIES
IN DEVELOPED COUNTRIES
1. Significant correlations between salt intake and hypertension has
been found in most, but not all studies
2. The Intersalt Cooperative Research Group
measured 24-h urine electrolytes and BP in > 10,000 individuals
aged 20-59 y in 52 places around the world
Showed a positive correlation between Na excretion and both
SBP & DBP and the increase in BP with age
Threshold: < 100 mmol per day
Meta-analysis of randomized controlled trials
A reduction of sodium intake lowers BP
Urinary sodium excretion is associated with changes in BP
DIET AND HYPERTENSION
POTENTIAL FOR PRIMARY PREVENTION OF HTN
A significant portion of CVD occurs in people whose BP is above
the optimal level (120/80 mm Hg) but not so high as to be diagnosed
or treated as HTN
Active treatment of established HTN, as carefully as can be provided
poses financial costs and potential adverse effects
Most patients with established HTN do not make sufficient lifestyle
changes, do not take medication, or do not take enough medication
to achieve control
Even if adequately treated according to current standards, patients
with HTN may not lower their risk to that of persons with normal BP
For every 3 mm Hg drop in SBP,
8 % decrease in mortality from stroke
5 % decrease in mortality from CHD
DIET AND HYPERTENSION
LIFESTYLE MODIFICATIONS
Key point:
Lifestyle modifications should be the cornerstone of the initial therapy for HTN
Clinical studies show that the blood pressure-lowering effects of lifestyle
modifications can be equivalent to drug monotherapy
Lifestyle modifications is best initiated and sustained through an educational
partnership between the patient and a multidisciplinary health care team
- team members may vary by clinical setting
- behavior change strategies include
- Nutrition
- Exercise
- Smoking cessation services
DIET AND HYPERTENSION
LIFESTYLE MODIFICATION
TO PREVENT AND MANAGE HYPERTENSION *
Modification
Recommendation
Approx. SBP reduction
Weight reduction
Maintain normal body weight
BMI = 18.5 – 24.9
Fruits, vegetables, low –fat dairy
low saturated fat
Reduce Na intake to no more
than 100 mmol/d ( 2.4 g Na or
6 g natrium chloride)
Engage in regular aerobic PA
(brisk walking ,30-45 min
per day, most days of the week)
Limit consumption to
2 drinks/d for M, 1 for F
5-10 mm Hg/ 10 kg weight loss
DASH* * eating plan
Dietary Sodium restriction
Increase physical activity
Moderation of alcohol
consumption ***
8-14 mm Hg
2-8 mm Hg
4-9 mm Hg
4-9 mm Hg
2-4 mm Hg
Lifestyle modification* JNC7 recommendations For overall CVD risk reduction, stop
DASH** indicates Dietary Approaches to Stop Hypertension
smoking
Alcohol consumption*** My point: Abstinence is better than moderation
DIET AND HYPERTENSION
DIETARY INTERVENTIONS
DASH (Dietary Approaches to Stop Hypertension) eating plan
in cohort studies
- reduced incidence of congestive heart failure by 25%
- reduced incidence of stroke by 17% in women
Modest sodium restriction
- reduces the amount of antihypertensive medications required
Individuals vary in response to a reduced sodium intake
Among hypertensives, African Americans, older patients, and patients with
renal diseases seem to be more Natrium sensitive
DIET AND HYPERTENSION
DASH STUDIES
(National Heart, Lung and Blood Institute)
First study
Tested nutrients as they occur together in the food
(in the past, researchers tested various single nutrients, such as Mg and Ca;
the studies – done mostly with dietary supplements and their findings were
not conclusive)
n = 459 adults, BP < 160/95 mm Hg
27% of the participants had hypertension
50% were women, 60% were African Americans
Groups (3) with different eating plans (3):
- similar to an American style
- similar to an American style, but higher in fruit and vegetables
- DASH diet
All three plans used about 3,000 mg of sodium daily
None of the plans were vegetarian or used specialty foods
Results: Both the fruits and vegetables and DASH diet reduced BP
DASH diet had the greatest effect, especially if patients had HTN
The blood pressure reductions came fast – within 2 weeks of starting the plan
DIET AND HYPERTENSION
DASH STUDIES
(National Heart, Lung and Blood Institute)
Second study DASH-Sodium
n = 412 participants,
SBP 120-159 mm Hg, DBP 80–95 mm Hg
41% participants had HTN, 57% women, 57% African American
Groups (2): control and DASH-Na diet
with eating plans (2), followed for one month
at each 3 Na levels: > 3,300 mg/d (high intake)
2,400 mg/d (intermediate intake)
1,500 mg/d ( lower intake)
Results:
Reducing dietary sodium lowered BP for both eating plans
At each Na level, BP was lower on the DASH diet vs. other diet
The biggest BP reduction was at DASH with 1,500 mg/d Na intake
Those with HTN had the biggest reductions, but those without it also
had large decrease
With 1,500 mg/d Na – fewer headaches.
DIET AND HYPERTENSION
THE DASH DIET
Food
group
Daily
servings
Grains
& grain
products
7-8
Vegetables
4-5
Fruits
4-5
Low-fat, or
Fat-free
Dairy
2-3
Serving
sizes
1 slice bread
1 oz dry cereals
½ cup cooked rice
pasta, cereals
1 cup raw leafy veg
½ cup cooked veg
6 oz veg juice
1 medium fruit
½ cup(90 g) fresh
frozen, canned
¼ cup(45 g) dried
180 ml juice
240 ml milk
240 ml yogurt
45 g cheese
Examples
and notes
whole wheat bread, English
muffin, pita bread, bagel
cereals, oatmeal, crackers
Significance
of each food group
energy and fiber
collards, kale, spinach, tomatoes
squash, broccoli, artichokes,
green beans, carrots, green peas
apricots, banana, dates, grapes
oranges, grapefruit, melons, plums
raisins, strawberries, pineapples
tangerines, mangos
K, Mg, fiber
fat-free(skim) or low-fat (1%)
milk, fat-free or low-fat yogurt
cheese
Ca, protein
K, Mg, fiber
DIET AND HYPERTENSION
THE DASH DIET
Food
group
Daily
servings
Serving
sizes
Examples
and notes
Meats
Poultry
Fish
2 or less
85 g cooked
select only lean, trim away visible fat
meat, poultry, fish broil, roast, or boil instead of frying
remove skin from poultry
Significance
of each food group
protein, Mg
Nuts,
4-5 per week 45 g nuts,
Almonds, filberts, peanuts, walnuts
Seeds
nut butter, seeds
sunflower seeds, sesame
Dry beans
½ cup cooked beans Kidney beans, lentils, garbanzo
energy, Mg, K,
protein, fiber
Fats
Oils
2-3
1 tsp (5g) margarine Soft margarine
1 tsp vegetable oil
Vegetable oil
fat 27% en
Sweets
5 per week
1 Tsp (15g) sugar
jam, honey , syrup
sweets should be
low in fat
jelly, sugar, jam, hard candy,
fruit drinks, sorbet, ices
The DASH eating plan is based on 2000 calories /day.
The number of daily servings in a food group may vary from those listed
depending on your caloric needs.
DIET AND HYPERTENSION
DIETARY FIBER
- may reduce BP
- results not consistent
- most studies that show results used whole foods:
- perhaps energy displaced and caused weight loss
- other minerals in whole grains like Mg involved
- role for fiber?
- substituting whole grain for refined CHO in heart healthy
diet reduces BP
DIET AND HYPERTENSION
When SFA is reduced to follow DASH diet
it is either replaced with CHO or MUFA
When SFA is replaced by CHO
- increased SBP and DBP
- especially when CHO is refined and has less dietary fiber
- maybe Hyper insulinemia induced by high refined CHO leads to
vascular resistance, Sodium retention and increased BP
DIET AND HYPERTENSION
When SFA is replaced by MUFA
- BP especially diastolic is low
- effect of MUFA disappears when total fat intake is high
(> 37 %)
- same effect in normo and hypertensive subjects
- mechanism
membrane fluidity
Insulin sensitivity
reduced structural alterations in arterial
vascular smooth muscle cells
improved vascular health
DIET AND HYPERTENSION
PUFA
N-6 PUFA not much studied
N-3 PUFA
- either protective or no effect
- dose needed for lowering BP is approx. 4 g/d
- most effective in hypertensive than in normotensive
individuals (useful for treatment and not for prevention)
Mechanism
increased endothelial derived relaxation factor
works through NO, molecular aspect
(+) Pg I3 and Tx A3 (vasodilation and anti-thrombosis)
DIET AND HYPERTENSION
LABEL LANGUAGE
Food labels can help choose items lower in sodium
and saturated fat & total fat.
Look for the following:
Phrase
What it means
SODIUM
Sodium free or salt free
Very low sodium
Low sodium
Low sodium meal
Reduced or less sodium
Light in sodium
Unsalted or no salt added
Less than 5 mg per serving
35 mg or less of sodium per serving
140 mg or less sodium per serving
140 mg or less sodium per 3 ½ oz (100 g)
at least 25% less sodium than regular version
50% less sodium than the regular version
No salt added to the product during processing
FAT
Fat free
Low-saturated fat
Low fat
Reduced fat
Light in fat
Less than 0.5 g per serving
1 g or less per serving
3 g or less per serving
At least 25% less fat than the regular version
Half the fat than the regular version
REFERENCES
Rasmussen BM, et al. Effects of dietary saturated, monounsaturated,
and n-3 FA on blood pressure in healthy subjects. AJCN, 2006, 83:221-226
th
The 7 Report of the Joint Committee on Prevention, Detection, Evaluation and
Treatment of High Blood Pressure. The JNC 7 Report * JAMA 289: 2560-2572, 2003
Dietary Approaches to Stop Hypertension DASH
Pubmed.org
www.pcrm.org
www.icsi.org
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