Vitamin D3 1000IU

Choosing D3 over D2 is usually the easy part. The questions worth asking are about the source, the units on the label and what else you already take.

A good fit if

• You want the form of vitamin D with the best evidence for raising your levels and keeping them up
• You're vegan or vegetarian and need D3 from lichen rather than sheep-wool lanolin
• You're comparing labels in micrograms and IU and want to convert properly before choosing
• Your doctor has set a dose after a blood test and you want a product that matches it
• You'll take it with a meal that has some fat in it, and want a format designed for that

Check with us first if

• You take thiazide diuretics (water tablets). Combined with vitamin D, they raise the risk of high blood calcium.
• You take digoxin or another cardiac glycoside (a type of heart medicine). Its effects may be stronger when vitamin D is taken with calcium.
• You take anticonvulsants, barbiturates, corticosteroids, orlistat or a statin. Each can change your vitamin D levels or be changed by them.
• You have coeliac disease, Crohn's disease, cystic fibrosis or untreated malabsorption, or have had bariatric surgery. Absorbing a fat-soluble vitamin can be unpredictable.
• You have kidney disease or a history of kidney stones. Dose and monitoring are a decision for your doctor.
• You're pregnant or breastfeeding. Set the dose with your midwife or doctor.
• You're buying for a baby or child. The upper limit under 12 months is 25 µg a day, which one adult capsule reaches on its own.
• You already take a multivitamin, calcium, fish oil, bone formula or immune formula. Check every label before adding more D3.
• You're looking at a 2,000 IU or 5,000 IU product from an overseas website. Those aren't listed in Australia and aren't regulated by the TGA for quality.
• You take any prescription medicine. A quick check with your doctor, pharmacist or our naturopaths first is the sensible step.

• Lanolin-derived D3 in an oil-filled capsule. Best known for: The default Australian product: colecalciferol suspended in an oil such as olive or sunflower. Absorption: Fat-soluble and already dissolved in oil, which is the simplest way to take a fat-soluble vitamin. Typical use: One capsule daily, most often 1,000 IU (25 µg), with a meal.
• Lichen-derived (animal-free) D3. Best known for: The vegan and vegetarian option, and the choice for anyone avoiding sheep-derived lanolin. Absorption: Chemically identical colecalciferol; lichens have been shown to contain genuine vitamin D3, not only D2. Typical use: Capsules and drops at the same strengths as lanolin-derived products, usually at a higher price.
• Oral spray or liquid drops. Best known for: Flexible dosing and an option where swallowing a capsule is difficult. Absorption: Still needs fat for absorption; the oil or emulsifier base matters more than the spray action. Typical use: One to a few sprays or drops daily; check the label for IU per spray, not IU per bottle.
• Dry D3 powder in a tablet or blend. Best known for: D3 built into calcium tablets, multivitamins, immune formulas and bone products. Absorption: Absorbed less predictably without fat in the meal than an oil-based capsule. Typical use: Often a small dose you did not go looking for. Add up every product you take.
• High-strength D3 above 1,000 IU. Best known for: 5,000 IU and similar strengths, common overseas and on international websites. Absorption: No different per microgram. The issue is the total daily amount, not the uptake. Typical use: Cannot be supplied as an Australian listed medicine at that strength; belongs in a conversation with your doctor after a blood test.

Reference values. Australia's recommended intakes are set for vitamin D overall, not D3 specifically. They're published in micrograms, but almost every Australian label uses international units (IU), which is where most dosing confusion starts. The conversion is simple: 1 µg = 40 IU. So the adult Adequate Intake of 5 µg is 200 IU, the 10 µg figure for ages 51–70 is 400 IU, and the 15 µg figure from age 71 is 600 IU.

Typical supplemental range. Australian D3 products usually come in three strengths. 400 IU (10 µg) is the usual drop for babies and children. 1,000 IU (25 µg) is the standard adult capsule, and also the legal maximum for a listed medicine, which is why so many products sit at exactly that number. Anything labelled 2,000 IU or 5,000 IU isn't listed in Australia at that strength.

Upper level. The NHMRC upper limit for vitamin D is 80 µg a day (3,200 IU) from age one, including during pregnancy and breastfeeding. For babies under 12 months it's 25 µg a day (1,000 IU), so a single adult capsule already reaches the infant limit. According to the NIH, vitamin D toxicity typically involves blood levels of 25-hydroxyvitamin D above 375 nmol/L.

Worth knowing. The simple rule: convert before you compare. A 1,000 IU capsule, a 25 µg capsule and a 0.025 mg capsule are the same dose written three ways, so a label that mixes units is worth a second look. What you need depends on your age, diet and health, so talk to one of our naturopaths.

Food first, where the diet allows it.

• Cod liver oil and oily fish such as salmon, trout and herring: the main dietary sources of D3 specifically (vitamin D in animal foods is D3, not D2)
• Egg yolk and liver: small amounts of D3; the yolk carries it, the white does not
• Mushrooms exposed to ultraviolet light: a useful vitamin D source, but it supplies D2, not D3 (relevant if the D3-versus-D2 difference matters to you)
• Fortified milks, plant milks, margarines and cereals: may be fortified with either D3 or D2 (the ingredient list will say colecalciferol or ergocalciferol)
• Sunlight on bare skin: not a food, but it is the body's own D3 route and the reason the Australian intake figures are set low

This list is the part of the page we will not shorten. If any of it applies to you, talk to one of our naturopaths or your doctor before starting.

• Hypercalcaemia, hypercalciuria or any condition causing them. Contraindicated.
• Hypervitaminosis D. Contraindicated.
• Nephrolithiasis (kidney stones) and severe renal impairment. Contraindicated outside medical direction.
• Hypersensitivity to any product ingredient. Contraindicated.
• Long-term daily doses above 1,000 IU. Serum calcium, urinary calcium and renal function should be monitored.
• Unit confusion. 25 µg equals 1,000 IU; a label read in the wrong unit is a 40-fold dosing error in either direction.
• Infants under 12 months. The Upper Level is 25 µg (1,000 IU) per day, the same as one standard adult capsule.
• Thiazide diuretics. Increased risk of hypercalcaemia.
• Digoxin and other cardiac glycosides. Effects may be accentuated with vitamin D plus calcium.
• Anticonvulsants and barbiturates. May reduce vitamin D effectiveness.
• Corticosteroids. Impair vitamin D metabolism and calcium absorption.
• Orlistat. Reduces absorption of fat-soluble vitamins.
• Statins. Bidirectional interaction reported via shared metabolic pathways.
• Malabsorption states: coeliac, Crohn's, cystic fibrosis, liver disease, bariatric surgery.
• Pregnancy and breastfeeding. Dose to be set with a midwife or doctor.
• Stacking. D3 also appears in multivitamins, calcium tablets, fish oils, bone and immune formulas.
• Nausea, vomiting, constipation, thirst, polyuria, weakness, apathy or confusion. Possible hypercalcaemia; seek advice.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before starting.