Vitamin C Zinc

Choosing between plain ascorbic acid and a buffered form is mostly about comfort, and it only takes a few quick questions. These are the ones our naturopaths ask in store.

A good fit if

• Plain vitamin C has never bothered your stomach, so you don't need a buffered form
• You take gram-level amounts and want a simple bulk powder
• You're watching your sodium or calcium, and would rather not add either through a buffered form
• You want as few added ingredients as possible, with no coatings, binders, flow agents or flavours

Check with us first if

• You have reflux, gastritis, stomach ulcers or a condition of the oesophagus. The acidity is the issue, and a buffered form is the usual answer.
• You get ongoing cramps, loose bowels or nausea at your current dose. That's unabsorbed vitamin C drawing water into your gut, so the dose or the form needs to change.
• You have kidney stones, diagnosed hyperoxaluria, kidney disease or reduced kidney function, since vitamin C is cleared through your kidneys.
• You take iron supplements or are being monitored for high iron. Vitamin C increases how much iron you absorb from plant foods and supplements (non-haem iron).
• You're having chemotherapy or radiotherapy. The NIH advises checking with your oncologist before taking high-dose antioxidant supplements.
• You take niacin together with simvastatin, where vitamin C may reduce the expected rise in HDL (good) cholesterol.

• Ascorbic acid, crystalline powder. Best known for: Vitamin C in its simplest form, with no excipients, coatings or binders at all. Absorption: The standard every other form is compared against. Nothing is added that could change absorption either way. Typical use: A quarter to half a teaspoon in water or juice, ideally split across the day rather than taken all at once.
• Ascorbic acid tablet or capsule. Best known for: A measured dose without scales or scoops, usually 500 mg or 1,000 mg. Absorption: The same molecule. The tablet has to break down first, so it meets the stomach lining as a concentrated piece. Typical use: One tablet with food. Taking it with a meal is the simplest fix for mild stomach discomfort.
• Sodium ascorbate (the buffered comparison). Best known for: Not acidic, which is why people prone to reflux switch to it. The trade-off is 111 mg of sodium in every gram. Absorption: Absorbed as the same ascorbate. Buffering changes the acidity in the glass, not how your gut takes it up. Typical use: Powders. Check it against your daily sodium if you're watching salt.
• Calcium ascorbate (the buffered comparison). Best known for: Not acidic, and it adds calcium: 90 to 110 mg in every gram, alongside 890 to 910 mg of ascorbic acid. Absorption: Also absorbed as ascorbate. The calcium counts towards your daily total, so that's the number to watch. Typical use: Tablets and powders. Suits people who want a buffered form without added sodium.
• Erythorbic acid (D-isoascorbic acid). Not vitamin C. Best known for: A mirror-image molecule used as a food antioxidant, and easy to mistake for the vitamin on a label. Absorption: Poorly absorbed and poorly held by the body's tissues, which is why it's only about a twentieth as effective as ascorbic acid at preventing scurvy. Typical use: A processing aid in food. If a label says erythorbic, it isn't giving you vitamin C.

Reference values. The NHMRC recommended intakes for vitamin C are measured as ascorbic acid, so the adult figure of 45 mg a day means 45 mg of ascorbic acid. Any product that lists a mineral ascorbate has to be converted back to that before you can compare it. The full figures by age, sex, pregnancy and breastfeeding are on our vitamin C page.

Typical supplemental range. Australian plain ascorbic acid tablets most often contain 500 mg or 1,000 mg. Powders are measured by the quarter to half teaspoon, around 1 to 2 g. A 500 g tub holds 500 one-gram doses, which is why people taking gram-level amounts usually choose powder over tablets.

Upper level. There's no NHMRC upper limit for vitamin C in any form. For plain ascorbic acid, the practical limit is comfort rather than safety, and some people reach it sooner than they would with a buffered form. That's exactly why buffered forms exist.

Worth knowing. Two habits make more difference than the form does: split the dose rather than taking it all at breakfast, and make up the drink just before you drink it. What you need depends on your age, diet and health, so talk to one of our naturopaths.

Food first, where the diet allows it.

• All fruit and vegetable vitamin C: is ascorbic acid. There is no separate 'natural' molecule: the vitamin C in a capsicum and the vitamin C in a tub are the same compound
• Boiled vegetables: ascorbic acid is water-soluble and heat-sensitive, so it leaches into the cooking water; steaming or microwaving retains more than boiling
• Cut, juiced or long-stored produce: oxidises on exposure to air over hours to days: the same reason a made-up ascorbic acid drink is best not left standing
• Foods with ascorbic acid added (listed as E300 or antioxidant 300): used as a processing antioxidant and flour treatment agent; the identical molecule, in amounts too small and undeclared to count as an intake

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

• You have reflux, gastritis, stomach ulcers or an oesophageal condition. The acidity of the plain form is the problem, so consider a buffered form.
• You have haemochromatosis or iron overload. NIH says high doses could worsen iron overload and cause tissue damage.
• You have diagnosed hyperoxaluria. Don't take doses of a gram or more.
• You have kidney stones, kidney disease or reduced kidney function. Talk to your doctor before taking high doses.
• You take iron or have your iron levels monitored. Ascorbic acid increases absorption of non-haem iron.
• You're having chemotherapy or radiotherapy. NIH advises talking to your oncologist about antioxidant supplements.
• You take niacin with simvastatin. Vitamin C may reduce the rise in HDL cholesterol.
• You get diarrhoea, nausea or stomach cramps. That's unabsorbed vitamin C drawing water into the gut, so reduce or split the dose.
• You're on a low-sodium diet. 1 g of sodium ascorbate contains 111 mg of sodium.
• You count or supplement your calcium. 1 g of calcium ascorbate gives 90 to 110 mg of calcium.
• You see erythorbic acid on a label. It's a food antioxidant with roughly a twentieth of vitamin C's scurvy-preventing strength, and not a vitamin C source.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before you start.