Vitamin B12 is an essential vitamin that plays many crucial roles in the body. Some people claim that B12 can help speed up metabolism and promote weight loss. But is there any truth to this?
B12 is involved in metabolizing fats and proteins, regulating energy levels, and supporting a healthy nervous system. It’s required for red blood cell formation, DNA synthesis, and myelin production. Myelin is the insulating sheath around nerves that allows for proper nerve signal transmission.
Given B12’s involvement in so many vital processes, it’s easy to see why some have theorized it may also be able to boost your metabolism. However, the research is still unclear on whether B12 has significant effects on metabolism and weight loss.
What is Vitamin B12?
Vitamin B12, also known as cobalamin, is a water-soluble B complex vitamin. It differs from other vitamins in that it contains a trace element: cobalt. Animals produce B12 internally, whereas plants do not. Therefore, people need to get B12 from animal-based foods or supplements.
B12 is essential for:
– Red blood cell formation and function
– DNA synthesis
– Energy production
– Proper nerve function
– Brain and nervous system health
Without adequate B12 levels, you’re at risk for neurological problems, fatigue, mood disorders, and megaloblastic anemia. This serious condition prevents your body from producing normal sized red blood cells.
The recommended daily intake of B12 is 2.4 mcg for adults. You can get this amount from foods like meat, eggs, and dairy products. Fortified cereals, nutritional yeast, and some types of algae also provide B12.
People at higher risk for B12 deficiency include:
– Vegans and vegetarians
– Older adults
– Those with digestive disorders affecting B12 absorption
– People taking heartburn medications long-term
– Those who’ve had weight loss surgery or digestive surgery
Supplements are often necessary for those who don’t get enough from dietary sources alone. The most common supplements are cyanocobalamin and methylcobalamin.
What Does Metabolism Mean?
Your metabolism refers to all the chemical reactions that keep your body functioning and alive. These include:
– Digesting foods and beverages
– Absorbing nutrients
– Converting nutrients into energy
– Transporting oxygen
– Regulating hormones
– Eliminating waste and toxins
Your basal metabolic rate (BMR) accounts for 60-70% of the calories you burn daily. It’s the number of calories your body needs for basic functioning at rest. Your BMR is determined mostly by:
– Age
– Sex
– Genetics
– Body size and composition
The other 30-40% of calories you expend daily comes from physical activity and digesting food.
Boosting your BMR isn’t typically feasible or sustainable. However, regular exercise and strength training can increase the number of calories you burn overall each day.
Can B12 Boost Metabolism?
Now that we’ve covered the basics of B12 and metabolism, let’s discuss whether vitamin B12 specifically can rev up your metabolic rate.
B12 for Energy
One of the most common symptoms of B12 deficiency is fatigue. Without enough B12, you may feel weak, sluggish, and physically drained.
Because B12 plays a role in cellular energy production, it makes sense that low levels could diminish your energy levels. Therefore, ensuring adequate B12 intake can potentially help increase natural feelings of vitality.
However, feelings of fatigue can have many causes beyond just B12 status. Make sure to rule out other common culprits like stress, poor sleep, thyroid issues, and iron deficiency.
B12 for Exercise Performance
Some research indicates B12 supplementation may enhance exercise performance and workout capacity.
In one study, vitamin B12 supplements improved oxygen utilization during exercise in young, healthy adults. This resulted in decreased heart rate and better exercise tolerance.
Another study found that B12 supplementation reduced perceived exertion during intense exercise in amateur boxers.
If B12 allows you to exercise harder and longer, this contributes to greater calorie burn during workouts. Over time, your body may adapt by building more metabolism-boosting muscle.
That said, more research is still needed to confirm whether B12 directly improves exercise performance and metabolism specifically.
B12 and Thyroid Function
The thyroid gland controls your body’s metabolic rate and energy balance. Even minor thyroid issues can disrupt your metabolism.
B12 deficiency and hypothyroidism often coincide. When your thyroid function is suboptimal, you may have symptoms like unexplained weight gain, fatigue, and sensitivity to cold.
Research demonstrates that correcting B12 deficiency can help normalize thyroid hormone levels in many cases. One study found that thyroid function partially improved in 24 out of 25 B12 deficient patients following B12 injections.
So there appears to be some link between B12 status and thyroid health. Ensuring you get enough B12 may help keep your thyroid functioning properly and prevent declines in metabolism.
B12 and Weight Loss
At this point, you may be wondering what impact B12 has specifically on body weight and composition.
Several studies suggest that higher B12 levels correlate with lower body weight:
– One study of around 200 overweight women found that blood levels of B12 were significantly lower among obese participants compared to normal weight participants.
– Another study found that for each unit increase in blood B12 levels, body mass index (BMI) decreased by 0.9.
– An analysis of the Framingham Offspring Study found that adults in the highest B12 intake group were 6% less likely to be obese.
However, all of these were observational studies, so they don’t prove cause and effect. Other factors beyond B12 status likely contributed to participants’ body weight.
Clinical trials attempting to link B12 supplementation with weight loss have had mixed results:
– In one trial, taking 500 mcg per day of oral B12 supplements for 6 weeks did not significantly affect body weight or body fat percentage compared to placebo.
– Another small study in obese adults showed that B12 injections led to nearly double the weight loss over 1 month compared to placebo injections. However, the reductions were modest, averaging just 2.2 pounds in the B12 group.
Overall, there’s no strong evidence that vitamin B12 supplementation yields significant weight loss, especially in the absence of an underlying deficiency.
Other Potential Effects of B12 on Metabolism
Here are some additional ways that ensuring optimal B12 status may help maintain a healthy metabolism:
– Supports liver function: The liver plays a central role in metabolizing nutrients and removing toxins from your body. B12 deficiency can manifest with elevated liver enzymes and fatty liver disease, indicating impaired liver function.
– Protects pancreas cells: Animal research demonstrates that B12 deficiency contributes to the death of insulin-producing beta cells in the pancreas. When fewer of these cells are present, your body produces less insulin to regulate blood sugar.
– Balances hormones: Thyroid hormones aren’t the only ones affected by low B12 levels. Research shows that B12 deficiency could also disrupt levels of melatonin, dopamine, and sex hormones like estrogen and testosterone. Keeping hormones balanced promotes proper metabolic function.
– Reduces inflammation: Chronic inflammation can disrupt healthy metabolic processes and worsen insulin resistance. B12 supplementation seems to decrease certain inflammatory markers like homocysteine and C-reactive protein (CRP).
– Supports lean muscle mass: As mentioned earlier, B12 is needed for protein metabolism. Without adequate B12, your body may break down lean tissue instead of using it to build and maintain muscle mass.
So in various ways, getting sufficient B12 intake sets the stage for better metabolic health and body composition. But directly speeding up your resting metabolic rate doesn’t appear to be its main mechanism of action.
Who is Most Likely to Benefit From B12?
While B12 has many vital roles in the body, that doesn’t necessarily mean more is better. Healthy people without deficiencies typically see no added metabolic benefit from taking B12 supplements or getting extra-high doses.
Those most likely to experience improved energy levels from B12 include:
– Vegans and vegetarians
– Older adults and the elderly
– Those with digestive conditions affecting absorption, like celiac disease or Crohn’s disease
– People who have undergone bariatric surgery for weight loss
– Those taking long-term acid-reducing medications
– Those with diagnosed B12 deficiencies causing symptoms
Without an underlying deficiency, your body will simply excrete excess B12 through urine. Megadoses are unnecessary and not likely to speed up metabolism or promote weight loss.
In fact, extremely high B12 intake from supplements may adversely affect lipids and blood sugar control, according to some research. Moderation is best, even with water-soluble vitamins.
Dosage Recommendations
The Recommended Dietary Allowance (RDA) for B12 is 2.4 mcg for adults up to age 50, and slightly higher for older adults. However, many experts suggest a daily intake between 5-30 mcg per day for optimal health.
Supplements and fortified foods can help you meet these intake levels if your diet is lacking in B12-rich foods. Keep in mind that your body doesn’t absorb supplemental B12 as efficiently as B12 obtained from foods.
Here are general dosage guidelines for B12 supplements based on your needs:
For Maintaining Adequate Status
– 25-100 mcg per day
For Addressing Deficiency
– 1000 mcg per day taken in divided doses
– Sublingual tablets or liquid drops may be preferable for absorption
– Most doctors recommend continuing high-dose supplementation for 1-2 weeks after deficiency is corrected
For Chronic Conditions Impacting Absorption
– 1000-2000 mcg per day orally OR 1000 mcg injected monthly
– Lifelong treatment is usually required
As always, it’s best to discuss correct dosage and form of B12 with your healthcare provider if you have a diagnosed deficiency or condition affecting absorption.
Food Sources of B12
While B12 is only found naturally in animal foods, you can also obtain it from fortified plant sources. Here are some of the top dietary sources and their B12 content:
Animal Sources
| Food | Serving | B12 Amount |
|---|---|---|
| Clams | 3 ounces | 84.1 mcg |
| Liver (beef) | 3 ounces | 70.7 mcg |
| Mackerel (cooked) | 3 ounces | 16.1 mcg |
| Tuna (canned) | 3 ounces | 2.5 mcg |
| Salmon (sockeye) | 3 ounces | 4.8 mcg |
| Eggs | 1 large | 0.6 mcg |
| Milk | 1 cup | 1.2 mcg |
| Yogurt (plain) | 6 ounces | 1.4 mcg |
Fortified and Plant Sources
| Food | Serving | B12 Amount |
|---|---|---|
| Nutritional yeast | 1 Tbsp | 2.4 mcg |
| Fortified plant milk | 1 cup | 2.5 mcg |
| Fortified cereal | 3/4 cup | 3 mcg |
| Noriii algae | 1 Tbsp | 8 mcg |
Vegans need to rely on fortified foods and/or supplements to meet their B12 needs. Nutritional yeast and nori are good plant-based ways to get B12.
Conclusion
In summary, here’s what the research tells us about B12 and metabolism:
– Vitamin B12 plays many essential roles related to energy production, exercise performance, hormone balance, and weight regulation.
– Ensuring adequate B12 intake can potentially help boost natural energy levels, improve workout capacity, support thyroid health, and reduce inflammation.
– These mechanisms may promote a healthy metabolism over time. However, B12 doesn’t appear to directly speed up resting metabolic rate on its own.
– Supplemental B12 seems unlikely to drive significant weight loss for those without deficiencies. But maintaining optimal B12 status supports metabolic health.
– Vegans, older adults, and those with absorption issues have the highest B12 requirements. Most benefit from 25-100 mcg per day through foods and/or supplements.
– While safe at moderate doses, mega-doses of B12 are unnecessary for the average healthy person and may pose risks when taken long-term.
So make sure to get enough vitamin B12 through a balanced diet with animal foods and/or fortified plant sources. But don’t expect high amounts of B12 supplements alone to supercharge your metabolism or fat burning.