Fortified foods such as some breakfast cereals and types of nutritional yeast can provide another cholesterol-free source of vitamin B12.
Image thanks to Krista.
Though it may be cheaper and easier to just take something once a week, some people would rather get into the habit of doing something daily, so they don't forget. So how much vitamin B12 would you have to take if you wanted to do it once a day rather than once a week?
Well, using the formula we just learned, 1.5 plus 0.01 times the quantity (x minus 1.5) equals 4 to 7; solve for x. I'll wait... Once a day, 250 micrograms or more is all we need. You can put it next to your toothbrush to remind yourself.
The reason we can't absorb more than about 1.5 at a time directly through our receptors is that they get filled up. But it only takes about 4 to 6 hours to unload their cargo into the body and then they're back in business.
So if we got B12 three times a day -- breakfast, lunch, and dinner -- we could absorb 1.5 each time and end up with 4.5 at the end of the day, which is all we need, and those kind of doses we can get from four to five foods.
The so-called "daily value" on Nutrition Facts labels for B12 is 6 micrograms. So as long as each serving contains 25% of our daily value, then we can eat a serving of B12-fortied foods at every meal, and we wouldn't have to take supplements at all!
So, for example, there's a vitamin B12-fortified nutritional yeast. Two teaspoons counts as a serving, so you could sprinkle that on your meals. But that would cost a few dollars a weeks, as opposed to just a few pennies a week for B12 supplements.
Whichever path you choose, these are not just recommendations for people eating plant-based diets. They're for anyone who wants to get a cholesterol-free source of vitamin B12.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is transcript contributed by Bruce A. Hamilton.
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Update: data heroically procured by Vesanto Melina suggests that the nutrition facts label of Red Star brand's "vegetarian support formula" nutritional yeast is misleading and that one may only get 0.9 mcg of vitamin B12 per teaspoon. So to serve as a sole source one would have to consume 2 teaspoons three times a day (4 to 6 hours apart). The video was updated and re-recorded on July 14, 2012 to reflect this fact. Thank you Vesanto!
Note that nutritional yeast doesn't naturally contain B12—it has to be fortified with the vitamin. So many formulations lack B12 completely. So for example, while Red Star brand's "vegetarian support formula" nutritional yeast is an excellent source of B12, their "elder support formula" doesn't have any (which makes no sense, as the Institute of Medicine recommends everyone over age 50 supplement with B12). So if you buy it in bulk and are relying on it for your B12, you may want to ask to see the package it came from just to check to make sure it has B12 in it. If you'd rather just take a supplement once a week, see yesterday's video of the day, Cheapest Source of Vitamin B12. And for an explanation on why fortified foods and supplements are the preferred source, see the video before that, Safest Source of B12. And to put the whole B12 issue in perspective, see Vegan B12 Deficiency: Putting It into Perspective. And if you're sick of learning about B12, there's only one more video in this five-part series, and there's always a thousand other topics to fall back on.
For more context, check out my associated blog post, Stool Size and Breast Cancer Risk.