Why are B12 supplements helpful?

[Jebus]

My iron is a different matter - my haemoglobin levels were always low, even before I became vegan, and last year I was put on iron tablets.

Before starting with iron tablets, did you try upping your intake of iron rich foods?

[brimstoneSalad]

My iron is a different matter - my haemoglobin levels were always low, even before I became vegan, and last year I was put on iron tablets.

Before starting with iron tablets, did you try upping your intake of iron rich foods?

Lentils are great for that. But what's more: vitamin C, which (like the iron fish thing Take5 mentioned) increases absorption of iron substantially.

They won't always do it on their own, but I'm not aware of any cases like that outside of women with heavy flow.
Nonetheless, the iron fish thing looks like a fun solution.

[brimstoneSalad]

I've been vegan for 14 years, and I've never taken a B12 supplement - never felt the need. My diet includes fortified yeast nutrient (Meridian) and also fortified nooch, so I guess this must be the reason that my B12 was fine from my blood test 7 months ago - I have another test this week.

Blood tests won't always catch it.

If you get your B12 level checked, please note that eating seaweeds can falsely inflate B12 levels. Methods for determining B12 levels do not distinguish between B12 and some inactive B12 analogues. Many seaweeds contain a variety of inactive B12 analogues. Someone who is eating large amounts of seaweed may have serum B12 levels well above normal, but much of it could be inactive B12 analogues.

http://www.veganhealth.org/b12/tested

Nutritional yeast can also have varying amounts, and you might need to eat a large quantity depending on your body's ability to absorb it.
It's much easier to take a supplement than deal with that.

See daily recs for B-12:
http://www.veganhealth.org/articles/dailyrecs

If you're getting that much from the nutritional yeast, you're probably fine. But then again, very cheap and easy to supplement and B-12 is one of those vitamins that it's hard to get too much of since the toxicity is very low.