Calcium Vitamin D3 150 Tablets

Choosing a calcium form mostly comes down to your stomach, your medicines and what you'd rather it was made from. These are the questions our naturopaths ask in store.

A good fit if

• You want the most calcium in each tablet
• You take it with meals and have normal stomach acid
• You want the form with the strongest evidence from bone trials
• You're happy to keep track of food and supplements together, because the upper limit counts both

Check with us first if

• You've had kidney stones. Randomised evidence with this exact form shows a higher risk, and calcium doesn't prevent stones either.
• You take lithium, which can raise blood calcium on its own.
• You take dolutegravir or another HIV antiretroviral. Calcium can greatly reduce how much of the medicine reaches your blood.
• You take thyroid medicine. Calcium carbonate can stop levothyroxine being absorbed properly, so take them at least 4 hours apart.
• You take quinolone antibiotics or iron. Take these a few hours apart from calcium too.
• You're postmenopausal and taking 1,000 mg a day. One combined analysis found a raised heart and blood vessel risk at that dose, although other reviews found none.
• You have low stomach acid or reflux, or take antacids regularly, because carbonate needs stomach acid to dissolve.

• Calcium carbonate (item 1070). Best known for: The most calcium per tablet. Absorption: 40% actual calcium by weight; it needs stomach acid, so take it with food. Typical use: The form used in the major bone and fracture trials.
• Calcium citrate (items 1073, 1074). Best known for: Absorbed without needing stomach acid. Absorption: About 21% actual calcium; head-to-head trials don't show it clearly does better for bones than carbonate. Typical use: A good choice if you take antacids or reflux medicine.
• Calcium amino acid chelate (item 1062). Best known for: The only calcium form with a legal limit on how much calcium it contains. Absorption: By law it can be no more than 25% calcium by weight (w/w); there's no absorption trial. Typical use: Check the actual calcium amount on the label; expect to take more capsules per dose.
• Calcium hydroxyapatite / MCHA (item 2643). Best known for: A whole bone-mineral complex rather than a simple salt. Absorption: In one 100-person trial, a smaller rise in blood calcium than citrate or carbonate, but a similar effect on markers of bone turnover. Typical use: When a gentler rise in blood calcium matters more than tablet size.
• Algae-derived calcium (items 1059, 1060). Best known for: A plant or marine source that also brings magnesium and trace minerals. Absorption: There's no published absorption or bone trial; the one 30-person trial only measured protein markers in the bowel lining. Typical use: Allowed in oral medicines only.

Reference values. The NHMRC recommended daily intake for calcium is 1,000 mg a day for most adults, rising to 1,300 mg for teenagers, women from 51 and men from 70. That applies to the calcium in carbonate just as it does to any other form.

Typical supplemental range. Calcium carbonate is about 40% elemental calcium (the actual calcium) by weight, the highest of any common form, so it takes the smallest tablet to reach a given dose. The landmark trial used 1,000 mg of calcium as carbonate with 400 IU of vitamin D3 a day. Check the milligrams of elemental calcium on the label, not the tablet weight.

Upper level. 2,500 mg of calcium a day from all sources, for everyone aged 1 and over. That's the same NHMRC upper limit that applies to every form of calcium.

Worth knowing. What you need depends on your age, diet and health, so talk to one of our naturopaths.

Food first, where the diet allows it.

• Dairy foods: the main Australian source of dietary calcium
• Bony fish such as tinned salmon and sardines: the bones are the calcium
• Legumes and some nuts: smaller contributions across the day
• Fortified soy drinks and cereals: fortification levels vary by brand; check the panel

If any of these sound like you, talk to one of our naturopaths or your doctor before you start.

• A history of kidney stones. In randomised trials using this exact form, calcium supplements raised kidney stone risk (HR 1.17), and they don't prevent stones either.
• Lithium. Long-term use can already raise blood calcium, and adding a calcium supplement could add to that.
• Dolutegravir and other HIV antiretrovirals. Calcium can greatly lower blood levels of the medicine.
• Thyroid medicine (levothyroxine). Calcium carbonate can interfere with how it's absorbed; take them at least 4 hours apart.
• Quinolone antibiotics or iron. Take these a few hours apart from any calcium dose.
• High blood calcium (hypercalcaemia). Don't start a calcium supplement without your doctor's OK.
• Upper limit. No more than 2,500 mg a day from all sources, for everyone aged 1 and over.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before starting.