From the Guidelines
Vitamin B12 supplementation is not recommended for weight loss in individuals with normal B12 levels, as the evidence supporting its use for this purpose is limited and generally only observed in those with pre-existing B12 deficiency. The connection between B12 and weight likely stems from the fatigue and weakness that accompany B12 deficiency, which can limit physical activity and potentially contribute to weight gain 1. While B12 is essential for energy metabolism and nerve function, research does not strongly support B12 supplements as effective weight loss aids in people who aren't deficient. Some weight loss clinics offer B12 injections (typically 1,000 mcg doses) claiming they boost energy and metabolism, but these effects are generally only observed in those with pre-existing B12 deficiency.
Key Points to Consider
- The most recent and highest quality study, published in 2024, found that there is no clear evidence that nutrition supplements, including vitamin B12, are effective for obesity management or weight loss 1.
- Several large systematic reviews have shown that most trials evaluating nutrition supplements for weight loss are of low quality and at high risk for bias, with high-quality published studies showing little or no weight loss benefits 1.
- Vitamin/mineral supplementation, including vitamin B12, may be indicated in cases of documented deficiency, but not for weight loss in individuals with normal levels 1.
- For effective weight management, focus on established approaches like calorie-appropriate diet, regular physical activity, adequate sleep, and stress management rather than B12 supplementation 1.
Recommendations for Practice
- If you suspect a B12 deficiency (common in vegans, older adults, and those with certain digestive conditions), it's better to seek proper diagnosis through blood testing rather than using B12 as a weight loss strategy.
- For individuals with normal B12 levels, supplementation is unlikely to affect weight, and other weight loss strategies should be prioritized.
From the Research
Vitamin B12 and Weight Loss
- There is no direct evidence in the provided studies to suggest that Vitamin B12 supplementation is effective for weight loss.
- The studies primarily focus on the importance of Vitamin B12 in preventing deficiency, its role in cellular metabolism, and its relationship with various health conditions such as megaloblastic anemia, neuropsychiatric symptoms, and depression 2, 3, 4, 5, 6.
- However, it is worth noting that some studies suggest that Vitamin B12 plays a role in energy metabolism and that deficiency may lead to fatigue and weakness, which could potentially impact weight loss efforts 4, 5.
- Additionally, one study mentions that patients who have had bariatric surgery should receive 1 mg of oral Vitamin B12 per day indefinitely, which may be relevant to weight loss in the context of bariatric surgery 2.
Vitamin B12 Deficiency and Health
- Vitamin B12 deficiency can have various health implications, including megaloblastic anemia, neuropsychiatric symptoms, and increased risk of depression 2, 3, 4, 6.
- The deficiency can be caused by inadequate intake, inadequate bioavailability, or malabsorption, and can affect individuals at all ages, particularly the elderly and those with restricted dietary intake of animal-derived foods 3, 4.
- Diagnostic biomarkers for Vitamin B12 status include decreased levels of circulating total B12 and transcobalamin-bound B12, and abnormally increased levels of homocysteine and methylmalonic acid 3, 4.
Vitamin B12 Supplementation
- Vitamin B12 supplementation can be effective in preventing and treating deficiency, and can be administered orally or parenterally 2, 5.
- The choice of supplementation form, such as methylcobalamin, cyancobalamin, or hydroxocobalamin, may depend on individual needs and circumstances 5.
- Some studies suggest that early supplementation with Vitamin B12 may delay the onset of depression and improve prognosis in patients with depression 6.