Yes, such a dose is safe for healthy adults. The recommended daily allowance (RDA) for B12 is only about 2.4 µg, but since it is a water-soluble vitamin, the body absorbs only a smaller portion of the amount taken orally, while the excess is excreted in urine, which is why no tolerable upper intake level has been established for it (NIH ODS). A clinical dose-finding trial showed that daily doses of approximately 650 to 1000 µg are needed to achieve 80-90% of the maximum effect in correcting lower B12 levels (Eussen et al., 2005), so a dose of 1000 µg is reasonable and consistent with expert guidance. Nevertheless, for long-term high-dose use, we recommend having your levels checked by a doctor if needed, especially if you are a smoker.

Cyanocobalamin is a synthetic, very stable form of vitamin B12 that the body converts in the liver into active forms (methylcobalamin and adenosylcobalamin). It is the most researched form, also used in reference clinical dosing studies (Eussen et al., 2005). Methylcobalamin is itself biologically active and, according to some data, may cross the blood-brain barrier more easily (Sil et al., 2018), but for healthy adults, no clear difference in final clinical effectiveness between the two forms at comparable doses has been demonstrated. Cyanocobalamin is therefore not an inferior choice, though it represents a slightly less direct route to the active form of the vitamin.

Metformin is one of the medications documented to potentially lower vitamin B12 levels in the body over the long term, and the same applies to stomach acid reducers (H2 blockers and proton pump inhibitors) (Varughese and Scarpello, 2007). This means that B12 supplementation is often reasonable for such patients, but we recommend consulting your doctor before regular use and regarding the appropriate dose, as they can assess your actual condition and, if necessary, suggest monitoring your blood B12 levels. This supplement is not a substitute for medical management of diabetes.

The pack contains 60 tablets, and at the recommended dose of one tablet per day, it will last for approximately two months of regular use. Since B12 is a water-soluble vitamin whose excess is continuously excreted, daily intake without special breaks is not problematic and is common practice for this category of supplements (NIH ODS). If you are vegan or vegetarian, regular long-term supplementation makes sense, as plant-based foods contain virtually no B12. However, if you are taking the supplement as a precaution without a known deficiency, you may want to ask a doctor or pharmacist whether continuous long-term use at high doses is advisable.