Clif Bloks Energy Chews

Choosing a vitamin C form is mostly about your stomach and what else you take. These are the questions our naturopaths ask in store.

A good fit if

• Plain vitamin C tastes too sour for you or brings on reflux
• You want a high-dose powder that dissolves completely in water
• You'd rather avoid the calcium in calcium ascorbate or Ester-C

Check with us first if

• You're on a low-sodium diet for blood pressure, heart failure or kidney disease. Sodium ascorbate adds sodium to your day, so check the label.
• You've had kidney stones or been told you make too much oxalate. Oxalate in urine rose at 1,000 mg of vitamin C a day.
• You're having chemotherapy or radiotherapy. The NIH advises talking to your oncologist before taking vitamin C or other antioxidant supplements.
• You take niacin with a statin. Vitamin C with other antioxidants may reduce the rise in HDL cholesterol from that combination.
• You take iron supplements or have your iron monitored. Vitamin C increases how much iron you absorb from plant foods and supplements (non-haem iron).
• It's for a child. Children need 35 to 40 mg a day, far less than a typical scoop.

• Sodium ascorbate. Best known for: Buffered, non-acidic vitamin C, usually sold as a high-dose powder. Absorption: No trial we hold compares it with ascorbic acid. Typical use: Powder dissolved in water or juice, often measured by the gram.
• Plain ascorbic acid (the comparison). Best known for: The form almost every vitamin C trial used, with no mineral added. Absorption: The benchmark: fully absorbed up to a single 200 mg dose, with absorption falling from 500 mg. Typical use: Tablets or powder, split across the day.
• Calcium ascorbate. Best known for: Buffered, non-acidic vitamin C with calcium instead of sodium. Absorption: No difference from ascorbic acid at 250 mg. At 500 mg, some white blood cell and immune measures differed, in one early single-dose trial. Typical use: Powder stirred into water or juice, or tablets.
• Ester-C. Best known for: Calcium ascorbate plus vitamin C breakdown products, and the one buffered form with a published stomach trial. Absorption: Higher vitamin C in white blood cells at 24 hours than ascorbic acid in a small trial, with no difference in the blood. Typical use: Buffered tablets, often 1,000 mg once a day.
• Liposomal vitamin C. Best known for: Vitamin C wrapped in phospholipid bubbles. Absorption: About 27% higher peak blood levels than standard vitamin C in one blinded 500 mg trial. Typical use: Liquids, softgels and capsules.

Reference values. Sodium ascorbate doesn't change how much vitamin C you need. The NHMRC RDI for adult men and women is 45 mg a day, rising to 60 mg in pregnancy and 85 mg while breastfeeding for ages 19 to 50. Children need 35 to 40 mg. Count the vitamin C, not the weight of the whole salt, because part of every gram is sodium.

Typical supplemental range. We haven't found a trial that tested a specific sodium ascorbate dose. Powders on the shelf usually provide anywhere from 500 mg to several grams of vitamin C a day. Check your label to see how much vitamin C one scoop gives you.

Upper level. Australia hasn't set an upper limit. In the NHMRC's words: 'It is not possible to establish a UL for vitamin C, but 1,000 mg/day is a prudent limit.' That's a limit for vitamin C, and it doesn't take into account the sodium that comes with this form.

Worth knowing. Your body absorbs all of a single 200 mg dose, but absorption drops from 500 mg upward, and the extra is passed out. So a large daily amount goes further split into two or three smaller doses. What you need depends on your age, diet and health, so talk to one of our naturopaths.

Food first, where the diet allows it.

• Red capsicum, raw, half a cup: 95 mg
• Orange, 1 medium: 70 mg, which already clears the adult RDI of 45 mg
• Kiwifruit, 1 medium: 64 mg
• Broccoli, cooked, half a cup: 51 mg

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

• You have hereditary haemochromatosis or iron overload. NIH lists iron overload among the concerns with too much vitamin C.
• You're on a low-sodium diet for blood pressure, heart failure or kidney disease. Sodium ascorbate adds to your daily sodium.
• You have kidney stones or hyperoxaluria. Oxalate and urate in the urine rose at 1,000 mg of vitamin C a day.
• You're having chemotherapy or radiotherapy. NIH advises talking to your oncologist before taking antioxidant supplements.
• You take niacin with simvastatin. Vitamin C with other antioxidants may reduce the rise in HDL cholesterol.
• You take iron or have your iron monitored. Vitamin C increases absorption of non-haem iron.
• You take high doses. NIH notes diarrhoea, nausea, stomach cramps and other stomach upsets.
• Children. The RDI is 35 to 40 mg a day.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before you start.