Compared to non-vegetarians, those removing meat from their diets tend to have healthier body weight, cholesterol, blood sugars, blood pressures, with a lower mortality rate due to a Schema Card disease, the number one killer of men and women. However, underestimate the importance of correct supplementation of vitamin B12 can nullify these benefits. Currently, the official position of associations and governmental agencies is categorical and unequivocal. In the case of a vegetarian diet, even if you eat eggs and dairy, in fact, I would extend that to flexitarians eating a few servings of meat a week. Supplementation of vitamin B12 is required. Now it's not just those eating plant-based that should be concerned about getting enough B12, but one in three non-vegetarians aren't getting enough for optimal health, and that may exceed half in women, especially when they're pregnant. But this number could run as high as nearly nine out of ten among those eating strictly plant-based, and ten out of ten doing it long-term. There are three groups of people who should ensure they have a regular, reliable source of vitamin B12 by supplementing their diet with vitamin B12, fortified foods or vitamin B12 supplements. Those who've had bariatric surgery, which can sometimes impair absorption, those eating plant-based diets, and the more than 100 million Americans older than age 50. Why can't you get regularly tested for signs of functional B12 deficiency like getting your homocysteine or methamelonic acid level tested? Though those are nearly always elevated in cases of B12 deficiency, there are rare cases. Of severe B12 deficiency manifesting with normal B12 levels in the blood, normal MMA levels, and normal homocysteine. How do we know it was B12 deficiency? Because within months of B12 treatment, they made a remarkable recovery. So best to just take it and not wait for symptoms to arise. The question is how much and how often? Some recommend a single dose of 50 to 100 micrograms a day or a thousand micrograms twice a week. Others suggest 50 to 150 a day. Some even recommend 500 micrograms a day. It all depends on the target levels you want in your body. For those with normal absorption capacity, meaning being under age 50, with an intact gastrointestinal system and without diseases like pranicious anemia, we normally lose about one microgram of vitamin B12 a day. So that's how much we have to replace on average every day. So why is the recommended daily allowance 2.4? Micrograms a day. Well, we only absorb about half of tiny doses of B12 we get in our diet. So by eating 2.4, we can make sure we absorb the one microgram into our body. To replace the one microgram we're losing every day. Taking larger doses like in supplement form, an even smaller fraction is absorbed. So it might take a single oral dose of 10 micrograms to get that one microgram absorption. But just 10 a day failed to sufficiently lower homocysteine levels to under 10 even after a year. So maybe we need to absorb more than that 1.6 micrograms every day for optimal health. The current RDA is primarily based on a 1958 study that just looked at a small number of patients and only measured their blood counts. Absorbing one microgram a day may be enough to maintain blood cell production, but may not be sufficient for all the other things that vitamin B12 does. Based on the date of several vitamin B12 status biomarker studies, maybe they recommended it and take for most adults should be raised to more like 4. Which is what you see for example in Europe suggesting they want people to absorb at least 2 into their body every day. In that case you need to take more than 50 a day. And now we have data suggesting getting 7 a day may be even better. So if you wanted to absorb 3.5 micrograms half of the intake that may optimize functional B12 status, how much would you need to take in a single daily dose? This chart isn't granular enough, but there's a formula you can use to calculate it. Use 10s for uptake, absorption into your body, and D is your single daily dose. To absorb 3.5, you theoretically need to take a single daily dose of about 225, which I round in my recommendations to 250 a day. Now that's just one of three methods you can use a simpler and cheaper way is to take a single dose a week. If you want 3.5 in a day, then you'd want to get at least 24.5 in you in a week. To get that in a single dose, you'd have to theoretically take about 2600, which I round in my recommendations to 2500. Okay, but that's theoretical. Maybe you need even more. Given the contrary, a new study showed you can get away with even less, just 50 a day, not 250, or 2001 a week, not 2500, reliably brought blood levels up, and more importantly, normalized mesoblonic acid, and almost 16 levels within a matter of months. So based on this new study, I dropped my supplement recommendations down to that 50 a day, or 2000 a week.