It’s true that when it comes to our bodies, one size rarely fits all. But one thing that does unite us is our almost universal need for vitamin B12. It’s one of those unique substances that does so much good that I urge anyone interested in health and longevity not to overlook it. 

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One big reason to keep your levels topped up? It’s great for brain health and keeping mood on an even keel – just what our difficult times require. What else can B12 do for you? Probably lots more than most people realize. Here’s a quick look at this incredibly helpful vitamin, and what you need to know to take advantage of it to the max:

The ABC’s of Vitamin B12.

First things first, what is it? B12 is a ‘water-soluble’ vitamin -- meaning it dissolves in the water circulating in the body – and it’s made up of cobalt plus a number of related compounds known as cobalamins. Your body stores a handy supply in the liver (by some estimates up to a few years’ worth) with any excess exiting via your urine. Due to its low toxicity, B12 is considered safe for most people even at high doses (thought there’s no reason to go overboard).

Your body’s got plans for that B12.

Why does B12 matter? Well, it’s got a lot of roles to play in any number of body functions, essential ones that need tending to if you want to stay vigorous and healthy for as long as possible. Among the six biggies that B12 is involved in:

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1. Helping heart health.

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What it does: B12 helps regulate levels of homocysteine, an amino acid in the blood.

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Why it matters: High levels of homocysteine are associated with an increased risk of cardiovascular diseases. B12, along with folate and vitamin B6, helps convert homocysteine to methionine, thereby reducing those homocysteine levels.

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2. Supporting better mental health.

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What it does: B12 is linked to the production of neurotransmitters like serotonin and dopamine, which regulate mood and assist in the transmission of nerve signals, connecting brain to body.

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Why it matters: B12 deficiencies can contribute to psychiatric problems, memory issues, depression and other mood disorders. These problems become more common with the advancing years, but they can show up at any age, including among children and adolescents. Most recently, a 2023 meta-analysis found a strong correlation B12 deficiencies and poor mental health particularly among the younger set.

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3. Maintaining healthy cognitive function.

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What it does: Adequate B12 levels are essential for maintaining cognitive function, including memory and concentration.

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Why it matters: For many people, a B12 deficiency can lead to cognitive decline and increased risk of dementia. In others, these deficiencies can cause cognitive impairment that mimic signs of dementia. Either way, big brain issues, big problems. 

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4. Supporting better neurological function.

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What it does: You need plenty of B12 to maintain the myelin sheath, the protective coating made mostly of fat, that surrounds and protects nerves.

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Why it matters: B12 deficiencies can lead to neurological problems, including numbness and tingling in the hands and feet, balance problems, and cognitive disturbances.

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5. Encouraging energy production.

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What it does: B12 is involved in the metabolism of fats and proteins and the conversion of carbohydrates into glucose, which the body uses for energy. 

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Why it matters: B12 deficiencies can trigger no or low energy symptoms like lethargy, physical (and mental) fatigue and weakness.

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6. Maintaining healthy red blood cell formation.

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What it does: B12 is essential for the production of healthy red blood cells, and in so doing, preventing anemia. 

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Why it matters: A deficiency can lead to megaloblastic anemia, characterized by large, immature red blood cells that cannot function properly, causing symptoms like fatigue and weakness.

Are you falling short?

Ok, so the next order of business is: are you getting enough B12? There are two ways to get clued in as to where you’re lining up. The first clue is, as is often the case, a few classic not-feeling-well symptoms such as:

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• Weakness and fatigue – a byproduct of red blood cell production that’s being impaired by B12 shortfalls.
• Neurological symptoms – including numbness, tingling, balance issues, and cognitive disturbances.
• Mouth ulcers – including Inflammation of the tongue and mouth sores.
• Mood changes – including depression, irritability, apathy, agitation, confusion, etc. 
• Loss of appetite and weight loss.
• Nausea, vomiting or diarrhea.

The other clue: advancing years. Granted, not a clue per se but a reality as we age. With each passing year, our ability to absorb B12 decreases due to reduced stomach acid production – so keeping an eye on the aforementioned symptoms becomes even more important as time marches on.

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Other candidates on the likely-to-fall-short list? Vegans and vegetarians, whose diets may make it difficult to get enough B12; those with GI disorders that impair absorption; and those whose needs increase due to pregnancy or breastfeeding. 

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So, if you’re experiencing some of the symptoms listed above and/or fall into one of the potential deficiency groups, consider asking your healthcare provider to order a routine blood test to check for vitamin B12 deficiency. For most people, a deficiency will be diagnosed if results come back with less than less than 150 per mL. of vitamin B12 in the blood. In some cases, if the deficiency is severe enough, extra measures, such as B12 injections may be warranted.

Grab a fork and dig in.

Assuming you fall into the not great, but not dire category, you can get your B12 on the regular either via food or with supplements, but food, particularly animal proteins, is the preferred place to start. High quality supplements are fine but, as regular readers of this blog know, I always recommend leaning into food sources whenever possible.

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What foods are the B12 go-tos? You won’t find much B12 in fruits and veggies (though mushrooms so get an honorable mention here), but there’s plenty to be had in fish, poultry, eggs, dairy products and meats. And yes, that can make things tricky for vegans and some types of vegetarians. However, for those of us who do eat animal proteins, know that the quality of the animal products is extremely important, so focus on the cleanest, healthiest sources possible, as in foods from local farmers’ markets and/or organic sources; free range and pastured animals; pole-caught small fish; and of course, no nutritionally-bankrupt, processed crap! In short, to get the most B12 bang for your buck be sure your shopping list includes:

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• Animal Products: B12 is naturally found in healthy animal products such as meat, fish, poultry, eggs, and dairy.
• Fortified Foods: Certain plant-based foods that are minimally processed but fortified with B12, like plant milks, nutritional yeast and vegan spreads.

When supplementing, consider bioavailability.

Another thing to think about is bioavailability as in the amount of B12 your body is able to absorb and put to good use – so more is definitely better here. The bioavailability of vitamin B12 from food can vary depending on the vitamin B12 dose in the food itself and by the type of food source. For example, the bioavailability of vitamin B12 is estimated to be roughly three times higher in dairy products compared to meat, fish, and poultry, and these items rank far above many veggies and fruits which, while they may contain B12, don’t have enough to make enough of an impact. 

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Knowing this, it’s easy to see the potential dietary downsides for those who are vegan or avoid animal proteins. However, the good news is that B12 supplements can help fill in much of the gap here because, according to the NIH, the bioavailability of vitamin B12 from dietary supplements is approximately 50% higher than that from food sources! So, what does that mean for most folks? Depending on how deficient (or not) you may be, it may be worth putting both B12 rich foods and some supplementation to work for you.