How to Test for Functional Vitamin B12 Deficiency

Many doctors mistakenly rely on serum B12 levels in the blood to test for vitamin B12 deficiency.



How did we end up here? Watch the full series if you haven’t yet:

Thanks for watching. I hope you’ll join in the evidence-based nutrition revolution!
-Michael Greger, MD FACLM

[NutritionFactsOrg]

I have updated my recommendation for B12 supplementation. I now suggest at least 2, 000 mcg (µg) cyanocobalamin once each week, ideally as a chewable, sublingual, or liquid supplement taken on an empty stomach, or at least 50 mcg daily of supplemental cyanocobalamin (you needn’t worry about taking too much). You can also do servings of B12-fortified foods three times a day (at each meal), each containing at least 190% of the Daily Value listed on the nutrition facts label (based on the new labeling mandated to start January 1, 2020—the target is 4.5 mcg three times a day). Note that those over age 65 only have basically one option, taking 1000 micrograms a day.

[blueskyes]

I had multiple B12 deficiency symptoms but had been taking sublingual B12 for years. My B12 serum was fine; my homocysteine & MMA (both urine & blood) were fine. MCV ok. Apparently adequate folate can mask B12 deficiency. BUT further testing showed a transcobalamin deficiency. So it was followed up with intrinsic factor antibody test. The test was positive for IF antibodies (12.9 A unit/mL). So that means a diagnosis of PA. It's incredibly complex.

[aaroiseverything]

Thx Dr Greger! looking forward to the final video!

[rjaquaponics]

This new format and constant teasing for the next video is undesirable at best! I used to be a huge supporter of Nutrition Facts, but it's become fluff ran like a sitcom! Time to get back to basics Dr. Greger!

[cyndijohnson]

I’ve read MTHFR variations are actually pretty common. This means those people affected can’t utilize cyanocobalamin properly, which is why methylcobalamin is better. Most people with MTHFR gene mutations don’t know they have it.

[theveganbossa]

Thank you for your valuable information 😊

[LindaR]

You just reminded me to take my Vitamin B supplement. I'm eagerly awaiting the next video on this.

[ankitgosain]

Great video sir..love your mannerism..nd it's good to finally put a face and all other details to tje voice i have heard in all the videos..

[jeffreywp]

Be sure to check with your insurance company before ordering a homocystiene test. Aetna covered it in 2018 for me but when my wife had it done they refused to pay and we got stuck with a $200 bill. It may require a pre-authorization. We went with MMA and folate tests. Just an FYI ...

[drvincentesposito]

Such a good point! Serum B12 should not be the only tested biomarker. MMA is great to study with serum B12 as well as homcysteine!

[bluegrasstrain]

I would love it if Dr. Greger would talk about the various types of vitamins added to fortify foods and the possible effect of synthetic, or synthesized vitamins on the body. I believe a form of B12, called cyanocobalamin which is derived from the cyanide molecule IS NOT SAFE for older people whose bodies cannot remove the cyanide via their kidneys as efficiently as younger people. Cyanocobalamin is more easily absorbed than the other forms of B12, but the other forms like methylcobalamin are retained longer in the body. I found that taking cyanocobalamin B12 triggered gout (an extremely painful form of arthritis) in my body. That’s when I realized that other vitamins used to fortify foods like white flour, could also trigger certain symptoms in my body like indigestion, arthritis aches & pains etc. So of course I try to avoid all processed, fortified foods. I’m too sensitive to the synthetic (created for patenting so must include slightly different formula from the formula for natural vitamins) vitamins- my body can’t utilize them - they end up being more poison than supplement.

[Adam-mcg-uk]

I wish Greger would talk about MTHFR gene mutations and ability to absorb cyanocobalamin

[robster]

What are your thoughts on adenocobalamin Dr Greger?

[gridcaster]

I can't wait to hear this at home b12 test...

[secnarfyerom]

What series? When and where is it available? Retiring minds want to know.

[nancyw]

If you're going to mention the next video, use YouTube functions to create clickable links on screen to get to the next one.

[EugeneFifchikus]

I've found B12 pills that have lactose in them. What does that mean, did anybody else have the same issue? Manufacturer said that there are no animal products involved but they might be lying

[KlaasVictor]

Thank you Dr Greger and team! You are saving lives every day!

[solarcrystal]

hope i don't die before the suggestion video is released

[philipmoravcik]

How the hell are we supposed to find "the next video in the series"?