Vitamin D

Question 1

What processes in the body is Vitamin D important for?

Answer 1

Cell growth
Immunity
Cell metabolism

Question 2

What are the clinical implications of vitamin D deficiency?

8

Answer 2

Rickets
Osteoporosis
Asthma
Autoimmune disease (RA and MS)
IBD
Disturbed muscle function
Resistance to TB
Pathogenesis of specific cancers
Diabetes
Enamel defects (caries)

Question 3

Is infant supplementation enough?

Answer 3

No.
Maternal vitamin D level during pregnancy and lactation has been implicated to the diseases caused by Vitamin D deficiency

Question 4

How do you define the optimal vitamin D level?

Answer 4

The optimal level is defined as at which PTH production and calcium reabsorption from bones are minimised and intestinal calcium absorption is stabilised.
between 75-225 nmol/L 25 OH Vit D

Question 5

Is there such thing as too much vitamin D and why?

Answer 5

Yes
> 225 - hypercalcemia and calcium deposits in tissues
> 500 mol/L - Toxic

Question 6

What is the physiological complications of hypo-Vit D?

Answer 6

decreased calcium absorption from the gut

tendency to hypocalcemia

Question 7

What are the factors that influence Vitamin D sufficiency?

Answer 7

1. Vitamin D3 is produced from precursors in the skin in response to UV rays (sunlight dependent)
   - this is affected by attitude, skin pigmentation, sunscreen, clothing.
   - skin Vit D production is minimised in infants. Also compounded by recommendations that infants not be exposed to direct sunlight 1 year, because of risk of cancer
2. BMI - requirements are weight dependent. There needs to be more research in this area to determine if we have to adjust the dose based on increased weight.
3. Maternal Vitamin D

Question 8

What happens to vitamin D in gestation?

Answer 8

Maternal calcium is used to create fetal skeleton in the third trimester. Rapid development of the foetus in the third trimester depletes maternal vitamin D because the foetus is entirely dependent on mom for source of Vitamin D (crosses the placenta)`

Question 9

Maternal hypo Vitamin D has what impact on the developing fetus?

Answer 9

Rickets
hypocalcemia
smaller size
dental malformation

Question 10

How much vitamin D should mom’s take?

Answer 10

at least 200 units

You should consider 2000 - 4000 units because it will minimise the need to supplement infants if breast feeding

Question 11

Why are premature infants at a higher risk of low vitamin D

Answer 11

decreased stores (occur in third trimester)
decreased volume of milk intake

Question 12

How much vitamin D supplementation is enough for babies?

Answer 12

Premature babies: 200-400 units per day
Full term: 400 units per day
Northern: 800 units per day

Question 13

How much volume of formula is sufficient for vitamin D intake

Answer 13

1 L will give 400 units

Question 14

What foods are good sources of vitamin d?

Answer 14

Tuna
canned salmon
fatty fish
seals
polar bears
fortified cereals

Question 15

Is breast milk enough source for vitamin D?

i.e. do breast fed babies 100% need to supplementaitons

Answer 15

Some people advocate that breast milk contains sufficient vitamin D. This may be true, however maternal low vitamin D is common and there is not a lot of vitamin D in breast milk. Therefore all breast fed babies should be supplemented. If moms really do not want to supplement babies, they can take 2000 - 4000 units themselves during pregnancy and lactaction

Question 16

Should children > 1 take vitamin D supplements?

Answer 16

the need for supplementation likely depends on sun exposure, latitude, skin pigmentation, time of year, sunscreen.
nonetheless recommendations for 200 units per day for kids 1-8

Question 17

Does the required supplementation of vitamin D change with age?

Answer 17

Yes
70 - 600 units

There is evidence and opinion the this is still not enough and that requirements may be as high as 2000-4000 units.