Vitamin B12: Essential for Health and Energy (Especially After 30)

Learn why vitamin B12 becomes essential for health and energy after age 30. Maintain adequate B12 levels to support brain health, red blood cells, and prevent deficiency.

As you age, especially after 30, it becomes increasingly important to monitor essential vitamins and nutrients for optimal health and energy.

One vital vitamin in particular, vitamin B12, is crucial for everything from red blood cell formation to DNA synthesis to neurological function. Yet as we get older, our ability to absorb vitamin B12 from food declines, putting many at risk of deficiency without realizing it.

The good news is, with increased awareness about this essential nutrient, proper diet, and supplements if needed, maintaining healthy B12 levels is within your control.

What Is Vitamin B12?

What Is Vitamin B12?

Vitamin B12, also known as cobalamin, is an essential nutrient that your body needs for proper red blood cell formation, DNA synthesis, and healthy neurological function. Vitamin B12 is a water-soluble B vitamin, meaning that your body does not store it.

As a result, you need to consume foods high in B12 or take supplements regularly to maintain adequate levels.

Vitamin B12 works with folate and vitamin B6 to convert the amino acid homocysteine into methionine, which is important for cognitive health and preventing conditions like dementia or Alzheimer's disease. B12 also helps produce red blood cells, which carry oxygen throughout your body.

Without enough B12, your body cannot produce healthy red blood cells, leading to a form of anemia called megaloblastic anemia.

Vitamin B12 Benefits: Supporting Energy, Mood and More

As you age, especially after 30, your body’s ability to absorb vitamin B12 naturally declines. Vitamin B12 plays an important role in many bodily functions, so maintaining adequate levels is essential for your health, energy, and mood.

Key Benefits of Vitamin B12

Vitamin B12 is vital for:

  • Red blood cell formation and preventing anemia. B12 helps produce healthy red blood cells to carry oxygen throughout your body. Without it, you can become anemic.
  • DNA synthesis. Vitamin B12 is necessary for creating new cells, especially red blood cells.
  • Nerve health and cognitive function. B12 protects nerve cells and is crucial for brain health. Deficiency can lead to memory problems, depression, and dementia.
  • Energy levels. By helping your body produce red blood cells, B12 gives you an energy boost and helps combat fatigue and weakness.

Vitamin B12 Deficiency: Why and How to Detect It

Why You Might Be Deficient

As you age, especially over 50, your body's ability to absorb vitamin B12 from foods and supplements decreases. Therefore, the recommended intake of B12 increases for adults over 50. Some signs of vitamin B12 deficiency include fatigue, weakness, constipation, loss of appetite, and depression.

Maintaining adequate B12 is essential for your health, energy, and mental well-being as you age. Whether through diet, supplements, or a combination of the two, be sure to get enough of this vital nutrient.

How Much Vitamin B12 Do You Need?

According to the National Institutes of Health, the recommended daily amounts of vitamin B12 are:

  • 2.4 micrograms for ages 14 and older
  • 2.6 micrograms for pregnant females
  • 2.8 micrograms for breastfeeding females

As you get older, your ability to absorb B12 from foods and supplements decreases, so you may need to take higher doses to maintain adequate levels, around 1,000 mcg per day. The upper limit for B12 is fairly high at 3,000 mcg per day for most adults.

Signs of Vitamin B12 Deficiency

Some common symptoms of vitamin B12 deficiency include:

  • Fatigue and low energy. Without B12, your body can't produce enough healthy red blood cells to carry oxygen.
  • Muscle weakness. Nerve damage from B12 deficiency can lead to muscle spasms, tremors, and loss of muscle mass.
  • Numbness or tingling. Vitamin B12 is essential for nerve health, and deficiency can cause numbness, pins and needles sensations, or nerve pain.
  • Cognitive difficulties. Low B12 levels are linked to memory problems, depression, confusion, and even dementia.
  • Gastrointestinal issues. Nausea, loss of appetite, constipation or diarrhea may indicate a B12 deficiency.

If you experience these symptoms, especially the neurological ones, see your doctor right away for a blood test to check your B12 levels and determine if supplements are needed. Early diagnosis and treatment of a vitamin B12 deficiency is important to avoid permanent damage.

Testing Your Vitamin B12 Levels

To properly monitor your vitamin B12 levels, regular testing is recommended. As you age, especially after 30, your ability to absorb vitamin B12 from foods decreases, putting you at higher risk of deficiency. The most accurate way to determine your B12 status is through blood testing.

Blood Serum B12 Test

A blood serum B12 test measures the amount of vitamin B12 in your bloodstream. Normal B12 levels are typically 200 to 900 picograms per milliliter (pg/mL).

Levels below 200 pg/mL indicate a B12 deficiency. However, some people may still have symptoms of deficiency even with levels in the lower end of the normal range.

If your levels are borderline or low, your doctor may recheck your levels or do additional testing to determine if you need B12 supplements or injections.

  • Homocysteine and methylmalonic acid (MMA) tests: These blood tests check levels of substances that build up when you don't have enough B12. Elevated levels indicate a B12 deficiency and can detect deficiency even when serum B12 levels are normal.
  • Holotranscobalamin (holoTC) test: This measures the form of B12 (holotranscobalamin II) that delivers B12 to cells. Low levels indicate poor B12 status even when other tests are normal.
  • Complete blood count (CBC): A CBC checks for anemia, which can be caused by B12 deficiency. High red blood cell count (macrocytosis) or large red blood cells (megaloblastic anemia) may indicate B12 deficiency.
  • Intrinsic factor antibodies test: Checks for autoantibodies against intrinsic factor, a protein needed to absorb B12. The presence of these antibodies blocks B12 absorption and causes an autoimmune condition known as pernicious anemia.
  • Methylmalonic acid (MMA) urine test: Elevated MMA in the urine also indicates a B12 deficiency. This can detect a deficiency when blood levels appear normal.
  • Parietal cell antibody test: Checks for antibodies against stomach cells that make intrinsic factor. The presence of these antibodies also indicates pernicious anemia.

Regular testing of your B12 levels, especially if you are over 30 or have symptoms of deficiency, is key to catching a deficiency early and avoiding potential long-term health issues. Be sure to discuss testing options with your doctor to determine what combination of tests is right for your situation.

Mito Health's flagship package, priced at $499, offers testing for Vitamin B12 as well as 66 other carefully curated biomarkers that provide insight into various aspects of your health - this comprehensive suite of tests allows for early detection of cancer, heart disease, neurodegenerative disorders, diabetes and more. 

In addition to testing, you will receive a personalized health optimization plan from our doctors incorporating supplements, nutrition, exercise and sleep strategies, discounted pricing for specialized additional tests, and access to exclusive health and longevity events.

Top 10 Food Sources of Vitamin B12

Vitamin B12 is essential for many critical functions in your body, especially as you age beyond 30 years old. The following foods are excellent sources of this important nutrient:

  • Beef liver - A 3-ounce serving of beef liver contains over 1300% of your daily need for vitamin B12. Beef liver is also high in many other nutrients like iron, folate and vitamin A.
  • Sardines - A 3.75-ounce serving of sardines contains over 300% of your daily need for vitamin B12. Sardines are also a great source of omega-3 fatty acids, calcium and protein.
  • Salmon - A 4-ounce serving of salmon contains over 80% of your daily need for vitamin B12. Salmon is also high in omega-3 fatty acids which are important for heart and brain health.
  • Tuna - A 3-ounce serving of tuna contains over 50% of your daily need for vitamin B12. Tuna also provides selenium, omega-3 fatty acids and protein.
  • Beef - A single 4-ounce hamburger patty contains around 30% of your daily need for vitamin B12. Beef also contains high amounts of protein, iron, zinc and selenium.
  • Nutritional Yeast -Two tablespoons of nutritional yeast provides 120% of your daily need for vitamin B12. Nutritional yeast has a savory, cheesy flavor and contains fiber, protein and various B vitamins.
  • Cheddar Cheese - One ounce of cheddar cheese contains about 15% of your daily need for vitamin B12. Cheddar cheese also provides calcium, phosphorus, protein and vitamin D.
  • Eggs - A single large egg contains about 10% of your daily need for vitamin B12. Eggs also contain high-quality protein and many vitamins and minerals like choline, selenium, vitamin D and riboflavin.
  • Milk - One cup of milk contains about 30% of your daily need for vitamin B12. Milk and other dairy products provide calcium, protein, vitamin D, phosphorus and riboflavin.
  • Clams - A 3-ounce serving of cooked clams contains over 1300% of your daily need for vitamin B12. Clams also provide iron, protein, manganese and other B vitamins.

Eating a variety of these vitamin B12-rich foods regularly can help ensure you get adequate amounts of this essential nutrient for optimal health, especially after age 30.

Vitamin B12 Supplements: Types, Dosage and Safety

Vitamin B12 supplements come in several forms, allowing you to choose what best fits your needs and preferences. The most common types are:

  • Cyanocobalmin - a synthetic form of B12 found in most supplements and fortified foods.
  • Methylcobalamin - an active form of B12 and may be better absorbed than cyanocobalamin. Methylcobalamin supplements tend to cost a bit more but may be preferable for those with absorption issues.
  • Hydroxocobalamin - often used in B12 injections and high-dose oral supplements. It may offer improved absorption for some individuals compared to cyanocobalamin, although it tends to be more expensive.
  • Adenosylcobalamin - another active form of B12 used in some supplements. For those with certain metabolic defects, adenosylcobalamin may provide benefit.

In terms of dosage, the typical recommendation for most adults is 2.4 mcg per day. However, higher doses may be needed to correct a deficiency. A B12 supplement providing 25 to 100 mcg per day is a good maintenance dose for most people over 50 years of age.

Always follow the dosage instructions on your specific product and consult your doctor if you have questions about proper dosage or if your symptoms do not improve with treatment.

When taken as directed, B12 supplements are considered very safe with no upper limit. However, very high doses of B12 could potentially cause side effects such as diarrhea, blood clots, and liver inflammation. As with any supplement, you should talk to your doctor before taking high doses of B12 or if you experience any negative side effects. For most people, B12 supplements are a safe way to ensure you get adequate amounts of this essential vitamin.


As you've learned, vitamin B12 is essential for your health, especially as you age beyond 30. It provides energy, supports brain and nervous system health, and helps produce red blood cells. While most people get enough B12 from diet alone, some are at risk of deficiency and should consider supplements or B12 injections. The good news is B12 deficiency is often correctable.

At Mito Health, we specialize in advanced health diagnostics to test your Vitamin B12 levels (along with 66 other biomarkers) - to form a science-based, personalized health plan to help you optimize your health. Sign up for our flagship package today to take control of your health and your future.

Written By
J. Hsu
December 22, 2023
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The information provided by Mito Health is for improving health and wellness only, and not to be taken as medical advice or medical recommendations.

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