Midterm 2 Section 3

Question 1

micronutrients definition

Answer 1

needed in small (mg/microgram) amounts in the diet

metabolically essential nutrients (not synthesized, perform specific functions, deficiency will result without intake)

Question 2

why do metals need to be bound?

Answer 2

they are toxic when free

Question 3

where/how are minerals synthesized?

Answer 3

in the sun or in nuclear reactors

Question 4

major minerals
minerals in 60kg person

Answer 4

Ca, P, K, S, Na, Cl, Mg
Ca - 1150g, P - 600g, K - 210g, S - 150g, Na - 90g, Cl - 90g, Mg - 30g

Question 5

Trace minerals
trace minerals in 60kg person

Answer 5

Fe, Zn, Cu, Mn, I, Se
Fe - 2.4g, Zn - 2g, Cu - .09, Mn/I/Se - .02g

Question 6

electrolyte minerals
Na-K balance, where in cells

Answer 6

K, Na, Cl, Mg
K inside cells, Na outside cells (tears taste salty)

Question 7

vitamins
vitamers

Answer 7

essential organic micronutrients
different forms of vitamin with different functions and conversion between forms

Question 8

B vitamins function
examples of functions B1-B6 (no B4)

Answer 8

function as coenzymes in intermediary metabolism
B1 (thiamine) - TTP (thymidine triphosphate) for pyruvate decarboxylation
B2 (riboflavin) - FAD, FMN
B3 (Niacin) - NAD, NADP
B5 (pantothenic acid) - acetyl coA
B6 (pyroxidine, RDA based on protein intake) - PLP in transamination

Question 9

types of bone

Answer 9

cortical bone - compact bone that makes up the outer surface, and 80% of all bone

trabecular bone - spongy scaffolding bone that makes up 20% of bone and supports cortical bone
examples of trabecular bone: ends of long bones and vertebrae, metabolically active including RBC formation

Question 10

bone resorption
bone formation
osteoblasts produce

Answer 10

surface of bone is broken down by osteoclasts

osteoblasts synthesize new bone in resorption pits

osteoblasts produce collagen component of bone

Question 11

osteoporosis
prevalence stats in Canada

Answer 11

degradation of mostly trabecular bone
vertebrae lose bone mass and compress
bones become susceptible to fracture

prevalence: 30% of women, 20% of men

Question 12

screening for osteoporosis

Answer 12

DEXA scan pre and post menopause as a lot of bone loss happens during this time (20%)
osteoporosis is a pediatric disease
DEXA is low dose radiation and non-invasive

Question 13

osteopenia vs osteoporosis
T score means

Answer 13

of standard deviations below the mean established for young, healthy population

osteopenia: bone mineral density -1 to -2.5 T score
osteoporosis: bone mineral density >-2.5 T score

number of standard deviations below the mean for young, healthy person

Question 14

who is most at risk for osteoporosis and why?

Answer 14

women, because 20% bone mass loss during menopause due to decreased estrogen
men have greater bone mass, so bones have more of a buffer
hereditary factors (polygenic, some people absorb less calcium) and lifestyle
caucasians and asians at higher risk

Question 15

bone health team

Answer 15

players: osteoblasts, osteoclasts, collagen protein, Ca, P, Mg, F
coaches: vitamin D, parathyroid hormone and calcitonin
assistants: vitamins A, C and K

Question 16

acute functions of Ca

Answer 16

muscle contraction, nerve impulse transmission, blood clotting, immune function, blood pressure moderation

all acute functions are Ca as an ion in solution

must be maintained in precise homeostasis, physiological not diet based

Question 17

chronic functions of Ca

Answer 17

mineral of bones and teeth
maintains bone turnover

low blood calcium robs bones of calcium to maintain blood homeostasis
causes stunting in children and osteoporosis

Question 18

tetany

Answer 18

when blood Ca is low, causes muscle tremors

Question 19

what causes rigor mortis?

Answer 19

When someone dies, ions are no longer pumped, Ca binds myosin and causes muscle contraction

Question 20

low blood calcium pathway

Answer 20

low blood calcium triggers parathyroid gland releases PTH (parathyroid hormone) which targets the kidneys and bones to release Ca into the blood

Kidneys activate calcitriol

Calcitriol signals kidneys to reabsorb more Ca from urine, increase Ca release from bone into blood, and increase absorption of Ca in the SI

Question 21

high blood calcium pathway

Answer 21

high blood calcium triggers thyroid gland to produce calcitonin

Calcitonin signals osteoblasts to reuptake calcium into the bones and build bone

Question 22

why is the RDA difficult to set for Ca?

why is the RDA for pregnant and lactating women the same as the adult RDA?

Answer 22

• genetics affect peak bone density
• dietary intake doesn’t affect the short term affects as much
• pregnant women’s RDA is still 1000mg because hormone changes during pregnancy increase bioavailability during pregnancy and lactation

Question 23

percent of people that meet the RDA for calcium

Answer 23

90% of people consume 1000mg or less
10% consume the RDA

Question 24

Good sources of Ca

Answer 24

milk, yogurt, cheddar, tofu set with Ca, sardines
bok choy and broccoli are ok sources but well absorbed

Question 25

Calcium absorption is increased by Calcium absorption is decreased by

Answer 25

anabolic hormones, gastric acid, vitamin D, low phosphate intake aging, low stomach acid, vitamin D deficiency, high phosphate intake, high insoluble fiber intake, high phytate/oxalate intake

Question 26

bioavailability definition

Answer 26

degree to which a particular nutrient from a food source can be utilized

Question 27

Foods that decrease Ca bioavailability why is spinach a poor source of Ca?

Answer 27

insoluble fiber binds cations phytates: legumes, nuts and cereals oxalates: spinach, beets, celery, eggplant, okra, berries, nuts, tea and cocoa spinach is high in Ca but also high in oxalates, so only 5% bioavailability, whereas broccoli is 50% bioavailable

Question 28

who should take a Ca supplement? type of supplement recommended

Answer 28

those at risk for low Ca intake like lactose intolerance, vegan or milk allergy amino acid chelates ($$), Ca-based antacids, calcium citrate/gluconate/malate/carbonate, Ca chews dolomite/bone meal not recommended due to contamination multi-minerals can decrease absorption

Question 29

UL for Ca side effects of toxicity

Answer 29

UL is 2500mg milk alkali syndrome - metabolic alkalosis and renal failure compromised iron and other mineral status kidney stones vitamin D toxicity and increased serum Ca if also supplementing vitamin D contaminants from bone meal supplements

Question 30

Vitamin D synthesis

Answer 30

cholecalciferol synthesized from cholesterol from 10-15 minutes of summer sun on hands and face (UVB rays) decreases with age, dark skin, latitude and winter

Question 31

Foods high in vitamin D

Answer 31

fatty fish, egg yolks, liver, fortified milk

Question 32

Vitamin D pathway

Answer 32

Provitamin 7-dehydrocholesterol made in the liver from cholesterol In the skin, ultraviolet light converts 7-dehydrocholesterol into previtamin D3, which is then converted into D3 D3 (calciferol animal food sources), D2 (ergo calciferol, plant sources) from diet In the liver D3 is hydroxylated into 25-hydroxy vitamin D3 (calcidiol) In the kidneys D3 is hydroxylated again into 1,25-dihydroxy vitamin D3 (calcitriol) which is the active form

Question 33

which form of vitamin D can be stored?

Answer 33

calcidiol (the one made in the liver)

Question 34

Functions of vitamin D

Answer 34

required for calcium and phosphorus absorption regulates blood Ca stimulates osteoclasts stimulates bone calcification immunity and cell differentiation *see calcium pathway

Question 35

vitamin D hormone and vitamin functions

Answer 35

hormone: travels in the blood to be activated in the liver and kidneys, acts on target tissues bone, kidney and intestines, increases Ca availability for bone mineralization and remodeling vitamin: it is essential in the diet, with deficiency symptoms develop, it performs a specific function, we can't synthesize as much as we need

Question 36

RDA vitamin D

Answer 36

assumes inadequate sun exposure 15ug/day or 600 IU per day under 70 years old Above 70 is 20ug/800 IU

Question 37

vitamin D toxicity side effects

Answer 37

cannot occur from skin synthesis, only excess supplements/fish oil hypercalcemia - high blood calcium leads to calcification of soft tissues, disability and death can occur UL is 100ug/day (4000 IU)

Question 38

reasons for high vitamin D deficiency in Canada

Answer 38

winter, reliance on fortification, pregnant milk restricted intake, sunscreen recommendations

Question 39

Osteomalacia

Answer 39

vitamin D deficiency in adults, intake below 2.5 ug/day leads to decreased Ca absorption, loss of bone matrix and defective mineralization decreased bone remodeling and softening of bone bone pain and hip fracture risk

Question 40

Rickets

Answer 40

vitamin D deficiency in children growing bones don't mineralize properly softening of bones leads to bowed legs, stunting and teeth problems prevalence decreased with milk fortification, increasing again due to strictly breastfed babies

Question 41

Why should babies receive vitamin D supplementation while breastfeeding?

Answer 41

transfer in milk is regulated so it won't improve child's uptake if the mother supplements

Question 42

Phosphorus function in bone

Answer 42

with Ca forms hydroxyapatite mineral of bone high intake decreases Ca uptake due to competition typical intake is higher than RDA

Question 43

Magnesium function in bone

Answer 43

bone structure and regulation of mineralization vitamin D metabolism ATP synthesis other: blood clotting, muscle contraction (opposite of Ca), blood pressure regulation

Question 44

vitamin K function in bone

Answer 44

co-enzyme for post-translational modification of bone proteins deficiency results in poorly bound minerals

Question 45

vitamin A function in bone

Answer 45

bone remodeling osteoclast activity

Question 46

vitamin C function in bone

Answer 46

cofactor for collagen synthesis (organic matrix)

Question 47

best way to prevent osteoporosis

Answer 47

maximizing peak bone mass increases time it takes to get below fracture risk threshold

Question 48

rate of bone loss per year after 20s to 30s how to increase peak bone mass

Answer 48

1-2% per year, with increased losses during menopause for women diet and exercise before the age of 20 after 20, diet, exercise and drugs can slow decline but can't flatten it

Question 49

risk factors for osteoporosis protective factors for osteoporosis

Answer 49

older age, low BMI, caucasian, asian or hispanic, cigarettes, excessive alcohol, glucocorticoids, anticonvulsants, high P, Na and protein intake younger age, high BMI, African American, weight bearing exercise, diuretics, estrogen therapy, good lifetime diet

Question 50

how do smoking and alcohol increase risk of osteoporosis?

Answer 50

smoking - associated with low BMI, early menopause, low postmenopausal estrogen, decreased blood flow to bone alcohol - increased Ca excretion, associated with lower dairy intake, toxic to osteoblasts