D-vitamin – D2, D3 och vad en deklaration berättar

Öppna källan

Exact stored assigned original, including selected source sections; not a fresh full-page capture. Current official web text separately consulted.

URL: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
Source date: 2025-06-27
Acquisition: Complete contiguous selected NIH government paragraph blocks from the accessible official web reader. Direct HTTP 403 recorded without bypass. Inline link labels and references are retained; reader subscript notation D_{2}/D_{3} renders as D2/D3. No paraphrase, table, image or referenced third-party article is imported.

In foods and dietary supplements, vitamin D has two main forms, D2 (ergocalciferol) and D3 (cholecalciferol), that differ chemically only in their side-chain structures. Both forms are well absorbed in the small intestine. Absorption occurs by simple passive diffusion and by a mechanism that involves intestinal membrane carrier proteins [4 ]. The concurrent presence of fat in the gut enhances vitamin D absorption, but some vitamin D is absorbed even without dietary fat.

Neither aging nor obesity alters vitamin D absorption from the gut [4 ].

Vitamin D (also referred to as calciferol) is a fat-soluble vitamin that is naturally present in a few foods, added to others, and available as a dietary supplement. It is also produced endogenously when ultraviolet (UV) rays from sunlight strike the skin and trigger vitamin D synthesis.

Vitamin D obtained from sun exposure, foods, and supplements is biologically inert and must undergo two hydroxylations in the body for activation. The first hydroxylation, which occurs in the liver, converts vitamin D to 25-hydroxyvitamin D [25(OH)D], also known as calcidiol. The second hydroxylation occurs primarily in the kidney and forms the physiologically active 1,25-dihydroxyvitamin D [1,25(OH)2D], also known as calcitriol [1 ].

Vitamin D is present in dietary supplements as either vitamin D2 or vitamin D3. Both can raise the serum level of 25(OH)D. However, research shows that vitamin D3 increases serum 25(OH)D levels to a greater extent than vitamin D2 and can maintain those higher levels for longer periods of time.

Dietary supplements can contain vitamins D2 or D3. Vitamin D2 is manufactured using UV irradiation of ergosterol in yeast, and vitamin D3 is typically produced with irradiation of 7-dehydrocholesterol from lanolin obtained from the wool of sheep [13 ,31 ]. An animal-free version of vitamin D3 sourced from lichen is also available [32 ]. People who avoid all animal-sourced products can contact dietary supplement manufacturers to ask about their sourcing and processing techniques.

Both vitamins D2 and D3 raise serum 25(OH)D levels, and they seem to have equivalent ability to cure rickets [4 ]. In addition, most steps in the metabolism and actions of vitamins D2 and D3 are identical. However, most evidence indicates that vitamin D3 increases serum 25(OH)D levels to a greater extent and maintains these higher levels longer than vitamin D2, even though both forms are well absorbed in the gut [33-36 ].

Some studies have used dietary supplements containing the 25(OH)D3 form of vitamin D. Per equivalent microgram dose, 25(OH)D3 is three to five times as potent as vitamin D3 [37 ,38 ]. However, no 25(OH)D3 dietary supplements appear to be available to consumers on the U.S. market at this time [32 ].

Vitamin D toxicity can cause hypercalcemia, hypercalciuria, and high serum 25(OH)D concentrations; in extreme cases, it may lead to renal failure, calcification of soft tissues, cardiac arrhythmias, and death. Vitamin D toxicity is almost always a result of excessive intakes of vitamin D through supplements. Taking calcium supplements in combination with vitamin D supplements may increase the risk of certain adverse effects.

The Tolerable Upper Intake Level for vitamin D ranges from 25 to 100 mcg (1,000–4,000 IU), depending on age.

Excess amounts of vitamin D are toxic. Because vitamin D increases calcium absorption in the gastrointestinal tract, vitamin D toxicity results in marked hypercalcemia (total calcium greater than 11.1 mg/dL, beyond the normal range of 8.4–10.2 mg/dL), hypercalciuria, and high serum 25(OH)D levels (typically >375 nmol/l [150 ng/mL]) [158 ].

Hypercalcemia, in turn, can lead to nausea, vomiting, muscle weakness, neuropsychiatric disturbances, pain, loss of appetite, dehydration, polyuria, excessive thirst, and kidney stones.

In extreme cases, vitamin D toxicity causes renal failure, calcification of soft tissues throughout the body (including in coronary vessels and heart valves), cardiac arrhythmias, and even death. Vitamin D toxicity has been caused by consumption of dietary supplements that contained excessive vitamin D amounts because of manufacturing errors, that were taken inappropriately or in excessive amounts, or that were incorrectly prescribed by physicians, [158-160 ].

Experts do not believe that excessive sun exposure results in vitamin D toxicity because thermal activation of previtamin D3 in the skin gives rise to various non-vitamin D forms that limit formation of vitamin D3. Some vitamin D3 is also converted to nonactive forms [1 ]. However, frequent use of tanning beds, which provide artificial UV radiation, can lead to 25(OH)D levels well above 375 to 500 nmol/L (150–200 ng/mL) [161-163 ].

The combination of high intakes of calcium (about 2,100 mg/day from food and supplements) with moderate amounts of vitamin D (about 19 mcg [765 IU]/day from food and supplements) increased the risk of kidney stones by 17% over 7 years among 36,282 postmenopausal women who were randomly assigned to take 1,000 mg/day calcium and 10 mcg (400 IU)/day vitamin D or a placebo [164 ].

However, other, shorter (from 24 weeks to 5 years) clinical trials of vitamin D supplementation alone or with calcium in adults found greater risks of hypercalcemia and hypercalciuria, but not of kidney stones [165 ,166 ].

The FNB established ULs for vitamin D in 2010 (Table 4) [1 ]. While acknowledging that signs and symptoms of toxicity are unlikely at daily intakes below 250 mcg (10,000 IU), the FNB noted that even vitamin D intakes lower than the ULs might have adverse health effects over time.

The FNB recommended avoiding serum 25(OH)D levels above approximately 125 to 150 nmol/L (50–60 ng/mL), and it found that even lower serum levels (approximately 75–120 nmol/L [30–48 ng/mL]) are associated with increases in rates of all-cause mortality, risk of cancer at some sites (e.g., pancreas), risk of cardiovascular events, and number of falls and fractures among older adults.

Öppna källan

Full exact imported definitions of the listed distinct identities; a collection is not an identity merge

{"id":"chebi-27300","version_id":"a46dba1b-9714-4cff-8705-b6ce4054f782","name":"vitamin D","definition":"Any member of a group of fat-soluble hydroxy seco-steroids that exhibit biological activity against vitamin D deficiency. Vitamin D  can be obtained from sun exposure, food and supplements and is biologically inactive and converted into the biologically active calcitriol via double hydroxylation in the body."}

{"id":"chebi-28940","version_id":"a7edbefc-c953-4f43-b3ae-6e69f94c6544","name":"calciol","definition":"A hydroxy seco-steroid that is (5<i>Z</i>,7<i>E</i>)-9,10-secocholesta-5,7,10(19)-triene in which the <em>pro</em>-<i>S</i> hydrogen at position 3 has been replaced by a hydroxy group. It is the inactive form of vitamin D<small><sub>3</sub></small>, being hydroxylated in the liver to calcidiol (25-hydroxyvitamin D<small><sub>3</sub></small>), which is then further hydroxylated in the kidney to give calcitriol (1,25-dihydroxyvitamin D<small><sub>3</sub></small>), the active hormone."}

{"id":"chebi-28934","version_id":"1fe3ae09-cf66-42f5-b3e0-d14c30c188c4","name":"vitamin D2","definition":"A vitamin D supplement and has been isolated from alfalfa."}

Läs produktdeklarationen på ActiQs

Supplement Facts
Serving Size: 1 tablet (4.4 g) (makes 16 fl-oz/475 ml prepared)
Servings Per Container: 12
	Amount Per Serving	%Daily Value*
Calories	10	
Total Fat	0 g	0%
Total Carb	4 g	1%
Total Sugars	2 g	
Incl 2 g added sugars		4%
Vitamin A (as retinyl acetate)	112.5 mcg	13%
Vitamin C (as ascorbic acid)	10 mg	11%
Vitamin D (as ergocalciferol)	5 mcg	25%
Vitamin E (as d-alpha tocopherol acetate)	2 mg	13%
Vitamin B6 (as pyridoxal-5 phosphate)	0.25 mg	15%
Folic Acid (as folic acid)	136 mcg DFE	34%
Calcium (as calcium carbonate)	15 mg	<2%
Magnesium (as magnesium oxide)	15 mg	4%
Chloride (as Himalayan Sea Salt)	75 mg	3%
Sodium (as Himalayan Sea Salt, sodium carbonate)	100 mg	4%
Potassium (as potassium bicarbonate)	150 mg	3%
Organic Green Tea Extract (containing 40 mg caffeine)	41 mg	†
*Percent Daily Values (DV) are based on a 2000 calorie diet. 
†Daily Value (DV) not established.

Dextrose, citric acid, natural flavors, beet powder color, stevia leaf extract, avocado oil, riboflavin (for color).

Läs produktdeklarationen på ActiQs

Kalciumkarbonat, magnesiumhydroxsid, fyllnadsmedel (tvärbundet natriumkarboximetylcellulosa) ytbehandlingsmedel (magnesiumsalter av fettsyror, hydroxipropylmetylcellulosa, talk, modifierad stärkelse, hydroxipropylcellulosa, karnaubavax), vegetabilsk olja (från kokosnöt), vitamin D (kolekalciferol).

Innehåll	per 1 tablett	% av DRI	per 2 tabletter	% av DRI	

Kalcium	300 mg	38%	600 mg	76%	

Magnesium	150 mg	40%	300 mg	80%	

Vitamin D3	20 ug	400%	40 ug	800%	


DRI = Dagligt referensintag