Fluid and Electrolytes Focus on Hypertension and Bone Health Flashcards
water
- carries nutrient and waste products
- assists in metabolic reactions
- regulates body temperature
- maintains BP and structure of large molecules
- lubricates and cushions many body parts
body water content
- 60% of body weight
- dependent on body composition
- 3/4 weight in lean tissue
- 1/4 in fat tissue
- proportion of water is smallest in: females, obese, elderly as they are associated with < lean tissue
water sources and losses
total water sources = total losses
for adequate hydration
- dehydration can be evaluated on the colour of urine (pale yellow = adequate hydration)
water recommendations
AI from food AND beverages:
2.7 L per day - women
- 7 L per day - men
- choose beverages with lower energy
- can include caffeinated drinks (coffee/tea has lower diuretic than once thought)
- alcohol does not count! (strong diuretic)
water balance
- every cell contains and is surrounded by fluid
- 2/3 of fluid is intracellular
- 1/3 extracellular
electrolytes
- electrolytes: are slats that dissolve in water and dissociate into ions (charged particles)
- electrolytes maintain fluid balance inside and outside of the cell and attract water by osmosis
- wherever electrolytes move, water will follow
sodium
principal cation in extracellular fluids
prime regulator of fluid volume and BP
- maintains acid/base balance
- essential to nerve impulse transmission & muscle contraction
sodium intake
people sensitive to high sodium intake have increased risk of hypertension
- risk factor for stroke, heart disease, kidney disease
high intake - increases calcium excretion
- effect on bone loss is uncertain
sodium intake in Canada
mean = 2760 mg/day AI = 1500 mg UL = 2300 mg
- we need salt in our diet, but too much = health risk
sources:
- 77% processed foods
- 12% naturally occurs in food
- 11% added by consumer
potassium
principal cation in intracellular fluids
- works with sodium to: maintain fluid balance, regulate nerve impulses and muscle contractions
high potassium diet = lower BP
AI - 4700 mg
Na & K - processed foods
processed foods: processing increases sodium content and reduce potassium
diet & hypertension
- limit processed foods
- increase intake of potassium rich: fruits/veggies. legumes, dairy, fish/meat
- limit alcohol, healthy body weight DASH Diet ( Dietary Approaches to Stop hypertension)
potassium rich foods
potato, whole baked
yogurt, non-fat plain
tomato juice
halibut
calcium
most abundant mineral in the body
99% in bones and teeth
- important part of bone structure providing a rigid frame
- serves as a calcium bank is calcium drops
1% circulates in body fluids
- regulates BP, blood clotting
- muscle contractions, nerve impulses
- hormone secretion
- MAY protect against hypertension and help weight management (findings are mixed)
inadequate calcium intake
bones give up calcium to maintain stable blood calcium
calcium balance
parathyroid hormone (released from parathyroid gland) = activation of vitamin d
calcitonin (released from thyroid gland) = inhibit vit. D activation
Vitamin D (acts on target tissues to ↑ or ↓ blood calcium).
Calcium RDA
RDA: 1000 mg (19-50
yrs)
adolescents: 1300 mg
F > 50y = 1200mg
M>70y = 1200mg
Calcium UL
2500mg
calcium absorption
absorption is quite poor across most foods (and supplements), including dairy
absorption rates in non dairy sources of calcium - highly variable
bone mineralization
process in which calcium and other minerals crystallize on the collagen matrix of a growing bone
bone health
- bones gain and lose calcium continuously in a process called remodeling (role of osteoclasts - erode bone and osteoblasts- build new bone)
- bone mass influenced by:
age, gender, genetics & ethnicity, lifestyle behaviours
peak bone mass
highest attainable bone density for an individual
- achieved by ~ age 30
Attainment of peak bone mass in youth, serves as best protection against bone loss later in life
vitamin D (calciferol) roles in body
maintains: blood concentrations of calcium and phosphorus
Vitamin D food sources
fatty fish, beef, egg, liver, fortified milk/butter/cereals/juice
sun exposure RDA
15 ug (600 IU)
process of sunlight into Vitamin D
- ultraviolet sunlight activates 7-dehydrocholesterol on skin – converted to provitamin D3 – undergoes 2 hydroxylation reactions in liver and kidneys to produce 1, 25 dihydroxyvitamin D3 (Calcitriol = active form)
Rickets and vit. D
symptoms vary with severity - defective bone growth and skeletal deformities in children
weak bones, can’t support weight - bowed legs
pain in the muscles and joints
softening of rib cage - respiratory problems (pneumonia)
fortification of milk and some breads has greatly reduced incidence of rickets
osteoporosis
condition in older people often detected later in life
- bones become porous & fragile due to loss of calcium
- increase risk fractures (hips, wrist, spine)
osteoporosis more common in
women > 50 y
associates with rapid loss of estrogen after menopause and reduced calcium absorption
osteoporosis risks
smoking and alcohol consumption ↑ risk
PA ↓ risk: stress on bones (weight bearing activity) and muscle attachments (resistance training) - ↑ bone density
DXA - Bone Mineral Density
Bone density test can detect early stages of bone loss (osteopenia) and osteoporosis, to determine risk for fractures.
Serves as a baseline measure and tracks response to treatment
This is a simple, quick non-invasive test usually recommended at age 65 - earlier in the presence of other risk factors.
preventing osteoporosis
- attainment of peak bone mass in youth
- lifetime diet rich in calcium AND vitamin D
- regular physical activity
- no smoking, moderate (or no) alcohol
calcium toxicity
calcium rigor, constipation, ↑ risk of kidney stones, ↓ absorption of other minerals (e.g. iron)
high calcium absorption food (>50%)
cauliflower, cabbage, brussels sprouts
