Hypertension 2 Flashcards
K inverse relationship with
High K consumption mechanisms
relationship w/ Na
Inverse relationship with BP and prevalence of HTN
Increases natriuresis
Suppresses renin
Attentuated vasoconstriction
Reduced sympathetic and AngII
Protective against familial susceptibility
The greater the BP increase due to Na (salt sensitivity) the greater the decrease from supplemental K
- greater intake of one increases excretion of the other
Mechanism that the western diet causes hypertension
Low K + ineffective K conservation
High Na + lack of renal adaptation/defects in Na excretion
Na retention + renal/fecal K loss —> causes more Na retention
Excess Na —> ECM expansion —> Digitalis-like factor (DLF) release —> Na/K ATPase promotes excess Na/deficit cellular K
Vascular smooth muscle contraction due to change in membrane potential —> increased peripheral resistance —> HTN !
Digitalis-like factor renal mechanism of action
Excess Na stimulates digitalis-like factor secretion
DLF stimulates basolateral Na-K pump —> increases blood Na and tubular K
Proximal tubule: K depletion stimulates symp/AngII —> NHE-3 Na-H+ apical exchanger reabsorbs Na to replenish cellular Na
Ascending loop: NKCC2 symporter mutation increases Na apical reabsorption
Distal tubule: Aldosterone increases NCC apical cotransport
Mechanism of vasoconstriction due to increased dietary Na and decreased K
Excess Na/K deficit -> digitalis-like factor INHIBITS Na-K ATPase in smooth muscle —> increased intracellular Na and decreased K
Decreased membrane potential —> Stimulation of NCX1 Na-Ca antiport —> increased intracellular Ca —> enters SR and triggers vascular contraction
AI for K in men and women and average intake
Recommendations
AI women = 2600 mg/d
AI men = 3400 mg/d
Average women = 2800 mg/d
Average men = 3300 mg/d
Recommendations: daily intake > 60 mmol (2300 mg) with no K supplementation (emphasize F&V)
K supplements indicated only for diuretic induced hypokalemia
Hyperkalemia risk factors
RAAS inhibitors
Drugs causing hyperkalemia
CKD GFR <60 mL/min/1.73^2
Baseline serum K >4.5 mmol/L
Rec: don’t increase intake or supplement
Ca relationship to BP and proposed mechanisms
Recommendations
Inverse relationship w/ BP (less effect than K)
Mechanisms:
Increased Na excretion
Increased NO sensitivity —> vasodilation
Decreased superoxide and prostanoid production (vasoconstrictors)
Rec: Ca supplementation to DRI (1000mg men, 1200 mg women) but not above for high BP prevention
Consume 2-3 servings of milk products daily is sufficient
Mg relationship to BP and potential mechanisms
Recommendations
Inverse relationship between Mg and BP
Mechanism: regulates vascular reactivity and contractility
Rec: Consume DRI (420 mg men, 320 mg/d women)
- supplementation above DRI not recommended
Alcohol and BP
Dose-response relationship over 2 drinks/day
Immediate vasovagal effect (BP decreases) bu long term elevated BP 10-15hrs
Mechanism: increased symp stimulation, cortisol, Ca uptake
Rec: limit 2 drinks/d (men) and 1 drink/d (women)
But no known safe level of alcohol despite moderate consumption not raising BP
Miliequivalent conversion
Mg/atomic weight x valence = mEq
Some studies express values like this
Nutrition diagnoses associated with HTN
Excessive energy intake
Excessive or inappropriate intake of fats
Excessive Na intake
Inadequate Ca, fiber, K or Mg
Overweight/obesity
Food/nutrition knowledge deficit
Assessment of people with HTN
Global: urinalysis, blood chem, FBG/A1c, serum lipids, ECG, target organ damage, CVD risk score, PA
Nutritional: dietary factors/patterns with nutrients of interest, need for weight control, alcohol, methods to meet DASH goals
Lifestyle recommendations for HTN
30-60 min/day 4-7 days per week moderate PA
- High intensity not more effective for BP
Gradual increase in PA
Resistance exercise up to 160/99 mm Hg
Reduce weight to normal BMI range
DASH diet + lower Na intake
DASH Diet benefits
High in nutrients of concern, non-animal protein, low-fat dairy and low in satfat and Na
Average decrease in BP and larger decrease in hypertensive subjects
Half effects observed with just increased F&V vs control
DASH description
~55% CHO
~27% total fat
~6% sat fat
~18% protein
30g fiber
500 mg Mg
Na <2300 mg
K 4700 mg
Ca 1250 mg
Main elements of DASH diet
Whole grain products - energy and fiber
Fibrous vegetables and tubers - K, Mg, fiber
Fruits - K, Mg, fiber
Low fat dairy - calcium and protein
Lean meats, remove skin and broiled, roast and poach - protein and Mg
Nuts - energy, Mg, protein and fiber
Margarine, vegetable oils, low-fat mayo and dressings - <30% kcal
Hard candy, gelatin, sorbet, maple syrup - low fat sweets
Benefits of the DASH Diet
OmniHeart Study findings
High fat DASH
Greater BP reduction in combination with low 1500 mg/d Na
- Associated with increased Ca, Mg, K and fiber while lowering satfat and Na
- Improves BP, LDL-C, VLDL, and TAGs
Diets similar in CHO, protein and MUFA/PUFAs reduced BP, LDL-C and CVD risk —> high protein + unsaturated FA further reduced BP in hypertensive people
High fat DASH diet reduced all except LDL-C but increased diameter (less atherogenic)
