Published on April 10th, 2012 | by Heather Nauta1
Eating Vegan: How Much Vitamin B12 Do You Really Need?
Vitamin B12 supplements are really important for vegans, for anyone with digestive issues and for older adults.
Although I would love nothing better than to tell you that all the nutrients you need are easily available from fresh, organic, whole plant foods B12 is unfortunately one nutrient that vegans in the developed world should be getting from supplements. But how much B12 do you need, and what are the best sources?
There are some plant foods (algaes, tempeh, etc) that list B12 in the nutritional info, but the trouble is these foods have a form of B12 that’s called an analogue, and haven’t been shown to prevent or correct a B12 deficiency. (Click for a more detailed look at studies of B12 in plant foods by Jack Norris.)
If someone suggests eating eggs or other animal foods to correct a vitamin B12 deficiency, keep in mind that B12 isn’t created by animals – it’s generated by bacteria. Supplements made from bacterial sources of B12 are a more direct form of B12. Also, the amount of animal foods you’d need to eat in order to absorb enough B12 is pretty huge.
With the health downsides of animal foods (hormones, antibiotics, cholesterol, saturated fat) along with the environmental impact and ethical considerations, supplements seem to me to be the best option. (Click for more info on why supplements are the safest source of B12 in Michael Greger’s video.)
Vitamin B12 Deficiency Symptoms
B12 is a pretty difficult vitamin for our digestive systems to break apart from food and absorb. For people who have less-than-perfect digestion, supplements are often a good thing to take. As we age, our digestive system becomes less effective, so older adults are prone to B12 deficiency. Interestingly, B12 deficiency symptoms are similar to senility and dementia, so it might be passed off as just part of the aging process.
If you think you might be low, you can check yourself for vitamin B12 deficiency symptoms and it’s a good idea to have your urine or blood tested for an objective and quantitative look.
For anyone who wants a detailed look at the science and studies of vitamin B12, Jack Norris has put together a very comprehensive series of articles in his vitamin B12 summary.
Vitamin B12 Supplements For Maintenance
Getting enough B12 on a regular basis is really important, and the best plan is to take B12 along with all of the other B vitamins as a “complex”. Most good multivitamins include all of the B complex, including enough B12 for daily maintenance.
Liquids, chewable tablets and capsules (cellulose ones for vegans) are the most easily absorbed supplements to take.
There are plenty of foods that are fortified with B vitamins, like non-dairy milks and certain brands of nutritional yeast. They’re fine as a source of B12, but since they’re processed foods you may want to minimize them for other reasons.
Another thing to consider is that the manufacturer of fortified foods might use a low-quality version that’s not as active as a high-quality supplement. They also might not say exactly how much B12 you’re getting from a serving of the food.
Vitamin B12 Supplements For Correcting A Deficiency
If you have a B12 deficiency, you’ll need to get the vitamin in much higher levels than what’s in a multivitamin until you catch up.
If you have a slight deficiency, or if your multivitamin doesn’t have enough B12 and the other B vitamins, your best bet is to take a full vitamin B complex. The B vitamins all work together in your body, so taking them together is a good idea.
If you have a more serious deficiency, and especially if you have an issue absorbing B12 through your digestive system, a sublingual vitamin B12 supplement is often what’s recommended.
Sublingual is a fancy name for a supplement that you hold under your tongue. The idea is that the vitamin gets absorbed directly into your blood stream through the thin skin on the underside of your tongue.
Apparently, though, sublingual supplements haven’t been shown to be any more effective than regular supplements that you swallow. A link to that study is on Jack Norris’ blog here.
The important thing is to get an easily-absorbed form of supplement (liquid, chewable or capsule) and to get the dose high enough to correct your deficiency.
People with a severe deficiency need to get B12 by injection. This would be something to discuss with a doctor after having your blood or urine levels tested.
How Much Vitamin B12 Should You Take?
The US RDA minimum for B12 is 2.4 mcg per day for adults, and 2.8 mcg for pregnant or nursing women. More recent studies put the ideal intake at 4-7 mcg per day. (Click for more info on optimum levels.)
The trouble is our bodies don’t absorb all of the B12 we take, and there’s kind of a cap on how much we absorb at one time. (Click for more info on how to calculate our body’s absorption rate.
The ideal would be to take smaller doses throughout the day. Since B vitamins stimulate energy and the nervous system, it’s better to take them in the morning and early afternoon so that you don’t get wired before going to sleep.
A B Complex that includes 250 mcg of B12 as cyanocobalamin daily should be enough for you to absorb what you need to maintain healthy levels. (As per Dr. Michael Greger’s latest recommendations [pdf].)
Methylcobalamin is reported to be a more active form of B12 and more effective than cyanocobalamin for smokers and for certain conditions like chronic kidney failure. The methyl form of B12 is found in higher quality supplements, but you need a higher dose of it (1000-2000 mcg) to make sure enough is absorbed.
If you’re trying to correct a vitamin B12 deficiency, you’ll need more than those amounts. The exact amount will depend on how low your levels are. It’s best to work with a doctor, naturopath or nutritionist to find the right dose to get you back on track.