Vitamin B12 100mcg

With B12, the question is really about you rather than the product. These are the questions our naturopaths ask in store, in the order they ask them.

A good fit if

• You eat little or no animal food. Only animal foods and fortified products provide B12 naturally
• You're over 50 and want the form the NIH recommends for your age group, from fortified food or a supplement
• You take metformin or an acid-reducing medicine long term, and your doctor has already checked your B12
• A blood test has shown a low result and you want a daily tablet to keep your levels up, alongside your doctor's advice
• You're choosing between a tablet, an under-the-tongue product and a spray, and you want the pros and cons, not a sales pitch

Check with us first if

• You take metformin. It may reduce B12 absorption and lower blood B12 significantly, so get your level checked rather than assuming a supplement covers it.
• You take a proton pump inhibitor such as omeprazole or lansoprazole, or an H2 blocker such as cimetidine or ranitidine. These reduce stomach acid and can get in the way of absorbing B12 from food.
• You're pregnant or breastfeeding and eat little or no animal food. A baby who is only breastfed by a mother who eats no animal products may have very low B12 stores.
• You're feeding a baby or child, where the dose and format are different questions from those for adults.
• You've had stomach or bowel surgery, including weight-loss surgery, or you have coeliac or Crohn's disease. Absorption is unpredictable, and tablets may not be enough.
• You already take a B complex, a multivitamin or a high-dose folate product. Large doses of folate can correct the anaemia of B12 deficiency while leaving nerve damage untreated.
• A blood test shows you have anaemia and the cause hasn't been found yet.
• You take any prescription medicine at all. A quick check with your doctor, pharmacist or our naturopaths first is the sensible step.

• Cyanocobalamin. Best known for: The most common form in supplements and fortified foods. Absorption: Stable and well studied; your body removes the cyanide group and converts it into the two active coenzymes. Typical use: Tablets and capsules from 100 µg upwards; the form used in most multivitamins.
• Methylcobalamin (mecobalamin). Best known for: The 'activated' or 'methylated' form, marketed as already converted. Absorption: One of the two coenzyme forms your body actually uses, but there's no evidence it's absorbed better than cyanocobalamin. Typical use: Tablets that dissolve under the tongue, chewables, sprays and liquids, commonly 1,000 µg to 2,500 µg.
• Adenosylcobalamin. Best known for: The coenzyme form used in your cells' mitochondria, usually paired with methylcobalamin in combination products. Absorption: The second active coenzyme form; there's little data comparing how well people absorb it. Typical use: Uncommon on its own, and it isn't in Schedule 1 under that name, or as cobamamide or dibencozide.
• Hydroxocobalamin. Best known for: The long-acting form used in medical injections. Absorption: Binds to proteins in the blood and lasts longer, which is why injections can be spaced weeks apart. Typical use: Injections given under medical supervision, and occasionally practitioner-only liquids taken by mouth.
• Sublingual tablets, lozenges and oral sprays. Best known for: The format chosen by people who assume the stomach is the problem. Absorption: NIH reports no difference in how well swallowed and under-the-tongue forms work. Typical use: Held under the tongue or sprayed into the mouth; convenient rather than measurably better.
• Injections. Best known for: The standard treatment where absorption has failed, such as pernicious anaemia. Absorption: Bypasses the stomach and intrinsic factor completely. Typical use: A decision for your doctor, not something to choose off the shelf. Very high doses by mouth are sometimes used instead.

Reference values. The NHMRC sets the Recommended Dietary Intake at 2.4 µg a day for everyone aged 14 and over, rising to 2.6 µg a day in pregnancy and 2.8 µg a day while breastfeeding. Children need 0.9 µg a day at 1–3 years, 1.2 µg at 4–8 and 1.8 µg at 9–13. Adequate Intakes for babies are 0.4 µg and 0.5 µg. The Estimated Average Requirement for adults is 2.0 µg a day.

Typical supplemental range. Australian labels range from 100 µg in a multivitamin to 1,000 µg in a single tablet, spray or under-the-tongue product, and up to 2,500 µg in practitioner ranges. Those numbers look huge next to a 2.4 µg requirement until you see how little is absorbed: about 2% at 500 µg and 1.3% at 1,000 µg. So a large dose is how you get a small amount in.

Upper level. The NHMRC set no upper limit. In its own words: "There are insufficient data to allow setting of a UL. There is no evidence that the current levels of intake from foods and supplements represent a health risk." The NIH adds that B12 hasn't been shown to cause harm, even at high doses.

Worth knowing. The NIH advises that people over 50 get most of their B12 from fortified foods or supplements, because those forms don't need to be released from food protein first. What you need depends on your age, diet and health, so talk to one of our naturopaths.

Food first, where the diet allows it.

• Beef liver, cooked: about 70.7 µg per 85 g: far and away the densest source
• Clams and oysters, cooked: roughly 17 µg and 14.9 µg per 85 g
• Fortified nutritional yeast: 8.3–24 µg per quarter cup, depending on the brand's fortification
• Salmon and lean beef, cooked: about 2.6 µg and 2.4 µg per 85 g
• Milk: about 1.3 µg per cup
• Egg: about 0.5 µg in one large egg

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

• You have pernicious anaemia or diagnosed B12 malabsorption. Supplements by mouth must not replace prescribed injections; that's a medical decision.
• You're allergic to cobalamin or any ingredient in the product. Don't take it.
• You have nerve symptoms such as numbness, tingling, unsteadiness, or changes in memory or vision. These need a medical assessment, not self-treatment.
• You have anaemia with no known cause. Find the cause before taking supplements.
• You take high-dose folate or folic acid at the same time. It can correct megaloblastic anaemia while leaving B12-related nerve damage untreated.
• You take metformin. It may reduce absorption and significantly lower blood B12 levels; monitoring is advised.
• You take a proton pump inhibitor (omeprazole, lansoprazole) or H2 blocker (cimetidine, ranitidine). These interfere with absorbing B12 from food.
• You've had stomach or bowel surgery, including weight-loss surgery. You absorb less B12 from food.
• You have coeliac disease or Crohn's disease. Absorption is impaired.
• You're pregnant or breastfeeding and eat no animal foods. Your baby's reserves may be very limited, so get advice.
• Babies and children. The dose and format differ from adult products.
• You're over 50. Atrophic gastritis affects 8–9% of people 65 and over; NIH advises fortified foods or supplements as your source.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before starting.