Hi Joan , mel and everyone
My understanding of vitamin D is that is should be supplemented alongside calcium for optimum absorbtion and activity .
The actual measurement of vitamin d levels is very difficult as it is stored in fat . Also because it is fat soluable it is possible to overdose . as unlike water soluable vitamins you don't pee out what you dont need .
The range for optimum working is relatively narrow . So both low and high levels have concerning problems attached .
The normal limits are :-
25- hyrdoxl - 37-200 nmol /l ( 0.15 - 0.45 ng/l )
( skin genrated vitamin D )
1,25 - dihyroxy - 60-108npmol /l ( 0.24 - 0.45 pg/l )
( skin generated vitamin D coverted in the kidneys )
24,25-(OH)2D3 - is a less active metabolite produced if vitamin d supplies are inadequate . Regulation is by parathyroid hormone , phosphate levels and feedback inhibition by 1, 25. This is logical . because if you ahve enough from these sources then you don't need the other
In assesing vitamin d level , the units should be taken notice of
Calcium needs vitamin D to be absorbed . 99 % of calcium is in the skeleton . When clacium levels drop , parathyroid hormone increases . This gives several actions to preserve calcium and increase absorbtion .
Low levels , leads to osteomalacia in adults ( rickets in children ) .
RDA's for the US :-
A new Dietary Reference Intake was made for vitamin D[33] on November 30, 2010 by the Institute of Medicine. The previous recommendation was an Adequate Intake (AI). The reference intake is based on more evidence than the previous AI. The recommendations were formed assuming the individual has
little to no sun exposure. The reference intake includes intake from diet (food and beverages) and supplements.
The new reference intakes for vitamin D are:
* 1–70 years of age: 600 IU/day (200 IU is 5 μg equivalent)
* 71+ years of age: 800 IU/day
* Pregnant/lactating: 600 IU/day
An AI remains for infants:
* 0–12 months: 400 IU/day
The upper level intakes for vitamin D are:
* 0–6 months of age: 1,000 IU
* 6–12 months of age: 1,500 IU
* 1–3 years of age: 2,500 IU
* 4–8 years of age: 3,000 IU
* 9-71+ years of age: 4,000 IU
* Pregnant/lactating: 4,000 IU[3
Dietry vitamin d is the same as skin produced vitamin d
. Interestingly it is uvb activity not direct sun exposure which allows production through the skin . So UVB on a cloudy day or in the shade allows vitamin d production . Even through non UV protective clothing .
Only 5 minutes of direct sun exposure is suffucent to stimulate production of vitamin D . Also sun cream allows enough UVB through for vitamin d production .( factor 20 and below ) So you can protect youreslf from sun exposure problems , both masto and skin cancer and continue to produce enough vitamin d .
If complete UV protection is needed dietry vitamin d is as useful as skin
Milk and diary products are whole foods . Bar vitamin c and fibre .
Other sources include :-
Supplemented cereals , breads and margarines . My olive oil margarine is supplemented
A whole egg provides 20 IU if egg weighs 60 g (0.33 IU/g)
Beef liver, cooked, 100 g (3.5 oz), provides 15 IU (0.15 IU/g)
# Fish liver oils, such as cod liver oil, 1 Tbs. (15 ml) provides 1360 IU (90.6 IU/ml) ????????????????????????????? Ok ??? Joan ?????
UV-irradiated mushrooms and UV-irradiated yeast are the only vegan sources of vitamin D from food stuffs.[4][36] A 100g portion provides: (regular) 14 IU (0.14 IU/g), (exposed to UV) 500 IU (5 IU/g)
Both yeast and mushroom materials, when irradiated with UV, produce vitamin D2, but it is not known whether the D2 is biologically fully equivalent to the D3 vitamin in humans.
The supplent of choice in the UK for bone protection and achieving absorbtion is :-
This is what BNF - the british national formulary which is the doctors prescribing bible here in the Uk . It is updated every 6 months . has to say about vitamin d replacemnet
9.6.4 Vitamin D
Note
The term Vitamin D is used for a range of compounds which possess the property of preventing or curing rickets. They include ergocalciferol (calciferol, vitamin D2), colecalciferol (vitamin D3), dihydrotachysterol, alfacalcidol (1α-hydroxycholecalciferol), and calcitriol (1,25-dihydroxycholecalciferol).
Simple vitamin D deficiency can be prevented by taking an oral supplement of only 10 micrograms (400 units) of ergocalciferol (calciferol, vitamin D2) or colecalciferol (vitamin D3) daily. Vitamin D deficiency can occur in people whose exposure to sunlight is limited and in those whose diet is deficient in vitamin D. In these individuals, ergocalciferol or colecalciferol in a dose of 20 micrograms (800 units) daily by mouth may be given to treat vitamin D deficiency; higher doses may be necessary for severe deficiency. Patients who do not respond should be referred to a specialist.
Preparations containing calcium with colecalciferol are available for the management of combined calcium and vitamin D deficiency, or for those at high risk of deficiency (see also Osteoporosis and Calcium Supplements).
Vitamin D deficiency caused by intestinal malabsorption or chronic liver disease usually requires vitamin D in pharmacological doses, such as ergocalciferol tablets up to 1 mg (40 000 units) daily; the hypocalcaemia of hypoparathyroidism often requires doses of up to 2.5 mg (100 000 units) daily in order to achieve normocalcaemia.
Vitamin D requires hydroxylation by the kidney to its active form, therefore the hydroxylated derivatives alfacalcidol or calcitriol should be prescribed if patients with severe renal impairment require vitamin D therapy. Calcitriol is also licensed for the management of postmenopausal osteoporosis.
Paricalcitol, a synthetic vitamin D analogue, is licensed for the prevention and treatment of secondary hyperparathyroidism associated with chronic renal failure (section 9.5.1.2).
Important. All patients receiving pharmacological doses of vitamin D should have their plasma-calcium concentration checked at intervals (initially once or twice weekly) and whenever nausea or vomiting occur.
Symptoms of vitamin d overdose :-
Side-effects
symptoms of overdosage include anorexia, lassitude, nausea and vomiting, diarrhoea, constipation, weight loss, polyuria, sweating, headache, thirst, vertigo, and raised concentrations of calcium and phosphate in plasma and urine ( BNf 2011 )
Low magnesium can accompany low calcium and should be treated alongside low calcium . ( BNF 2011)
Normal values for calcium are :- 2.20 - 2.67 mmol/l ( 8.5 -10.5 mg/dl ). Again both low and high levels can cause trouble . ( Kumar and clarke clinical medicine 6th ed , 2008 )
I hope this clarifies things .
Hugs
Josie xxxxxxxxxxxxxxxxxxxxxxxxx