Ca and bone health

Question 1

Absorption of Ca- where does it occur and how

Answer 1

Occurs passively in duodenum, jejunum, ileum when Ca intake is high; Active transport (effected by habitual intake via vitamin D) occurs in the duodenum when Ca intake is low/moderate.

Question 2

How does Ca intake correlate with absorption

Answer 2

increased Ca intake leads to increased bone accretion.

Question 3

Calcium absorption is enahced by _____________

Answer 3

Vitamin D, increased demand (pregnancy, adolescence), lactose (maintains solubility), gastric acidity, dietary protein

Question 4

Ca absorption is impaired by _____________

Answer 4

Vit D deficiency, steatorrhea (F.A. bind Ca and form soaps), oxalic acid (spinach), phytic acid (legumes, soy beans, corn, wheat), gastric alkalinity

Question 5

Excretion of Ca

Answer 5

regulated in kidney- can reabsorb or excrete Ca depending on hormonal signals

Question 6

Ca deficiency

Answer 6

Is rare b/c the body is able to maintain serum levels. It can develop over time though thus it is a long term, silent process.

Question 7

List critical stages of life for Ca intake

Answer 7

1. premature infants. 2. adolescence. 3. peri-menopause and after skeletal maturity. 4. pregnancy and lactation. 5. post-bariatric surgery

Question 8

Premature infants and Ca intake

Answer 8

There is a 3rd trimester period of rapid bone mineral accretion; preterm infants at risk for “osteopenia of prematurity

Question 9

Adolescence and Ca intake

Answer 9

Hormones during puberty favor Ca absorption and bone deposition. 50% of total adult bone mineral mass is accrued during adolescence. Ca absorption and retention is highest in early puberty.

Question 10

Ca intake after skeletal maturity

Answer 10

Associated with relatively high requirements, increased losses, and frequently with low intake

Question 11

Ca intake and pregnancy/lactation

Answer 11

Physiologic responses compensate for increased Ca demand so dietary requirements are not increased

Question 12

What proportion of bone mineral density is due to genetics

Answer 12

60-80%

Question 13

Sx of hypocalcemia

Answer 13

tetany, muscle spasm, seizure

Question 14

Conditions which can lead to hypocalcemia

Answer 14

1. life stages: premature infant, lactating adolescent, elderly (poor absorption). 2. pathological: Vit D deficiency, hypoparathyroidism, bariatric surgery

Question 15

How does the recommended daily intake of Ca change over the course of a persons life

Answer 15

The DRI is highest during adolescence, post-menopausal women, all people >70, pregnancy/lactating adolescent

Question 16

How does Ca RDA change during pregnancy/lactating (non-adolescent)

Answer 16

Physiological but not dietary requirements increase. During pregnancy, Ca absorption increases (active) to accommodate fetal demand. During lactation, PTH increases and bone mass is lost, but it is recovered by 6-12 months post-weaning

Question 17

Which foods have highest calcium

Answer 17

diary > salmon > tofu > greens > broccoli

Question 18

How does average Ca intake compare with RDA

Answer 18

Adolescent females and the elderly are not consuming enough Ca on average

Question 19

Ca supplements

Answer 19

1. Calcium carbonate (eg. TUMS)- best absorbed with meals. Has maximal elemental Ca per tablet and the least lead. 2. Calcium citrate malate- best absorbed between meals.

Question 20

How does Na affect Ca levels

Answer 20

Na intake increases Ca excretion in urine

Question 21

Which diet may improve serum Ca levels

Answer 21

DASH diet- reduction of Na decreases urine Ca and may have benefits to long term bone status. This diet also incorporates more Ca into it than traditional US diets

Question 22

How does Protein affect Ca levels

Answer 22

Increased protein intake correlates with increased absorption of Ca and increased urine Ca, so net effect is neutral or positive

Question 23

How does caffeine affect Ca levels

Answer 23

increases urine Ca excretion

Question 24

What happens if we don’t get enough Calcium?

Answer 24

Short term: Metabolic Regulation. Long term: Bone mineral depletion

Question 25

Outcomes of osteoporosis

Answer 25

25% of older persons w/ hip fracture die within first year from fracture related complications

Question 26

who is at risk for osteoporosis

Answer 26

Adolescents who become pregnant- the risk is greater if they do not have an adequate diet. Mexican american women, low bone mineral density, hypogonadism, older age, meds (corticosteroids), lifestyles

Question 27

Lifestyl factors that increase risk for osteoporosis

Answer 27

tobacco/alcohol increase risk. Weight bearing exercise decreases risk

Question 28

Nutritional factors associated with osteoporosis

Answer 28

1. low Ca intake. 2. low Vit D intake. 3. low protein intake. 4. high salt intake. 5. low fruit/veg intake. 6. caffeine intake

Question 29

Strategies to optimize bone density

Answer 29

Achieve “peak bone mass” when possible, consume enough Ca, Vit D, Vit K and protein, maintain ovulation/regular menses, weight bearing exercise, avoid smoking, alcohol, salt and steroids

Question 30

Should people > 50 yr take Ca++ Supplements

Answer 30

YES! Supplements are associated with 12% risk reduction in fractures of all types and reduced rate of bone loss (hip > spine)

Question 31

Medical conditions which increase risk of osteopenia

Answer 31

Chronic illnesses with malabsorption and/or chronic systemic inflammation. Crohns and UC: magnitude of steroid use is single strongest predictor of osteopenia. Obesity

Question 32

risks of Ca supplementation

Answer 32

may be associated with increased risk of MI when taken without Vit D.