Does Vitamin B12 Have Any Side Effects? Here’s What You Need to Know
Absorption
Let’s start with a quick overview of how vitamin B12 is absorbed by the body. When you take high doses of vitamin B12 orally, the absorption rate is quite low. For B12 to make it through the digestive process, it needs to bind with a protein called intrinsic factor. The amount of B12 that gets absorbed depends on the availability of this intrinsic factor. Because of this, taking large amounts of B12 orally is unlikely to cause any issues, as not all of it gets absorbed. Even sublingual absorption (through the tissues in the mouth) doesn’t reach concerning levels.
Symptoms of Deficiency
There are a couple of reasons why someone might end up with a B12 deficiency. One reason is not eating enough foods that contain B12, like red meat, fish, or dairy products, which is a common issue for vegetarians and vegans. Another reason might be the inability to digest B12 due to low levels of intrinsic factor, which can be caused by genetics or physical damage to the stomach or small intestine.
Common symptoms of a B12 deficiency include numbness in the hands and feet, moodiness, memory problems, dementia, poor red blood cell formation, impaired DNA function, and fatigue.
B-12 Side Effects
Vitamin B12 naturally occurs in three forms: methylcobalamin, adenosylcobalamin, and hydroxocobalamin. Cyanocobalamin, on the other hand, was created in a lab using cyanide to stabilize it, and many low-quality supplements contain this form. Injections are often used for people who can’t digest and absorb B12 properly. While vegetarians and vegans are more commonly B12 deficient due to their diet, even meat eaters can be surprisingly deficient.
Some side effects have been reported in patients receiving cyanocobalamin injections. These side effects include itching, acne, nausea, diarrhea, vascular thrombosis, headache, nervousness, and dizziness. However, studies show that a 1 mg injection of cyanocobalamin doesn’t cause any significant side effects.
No Upper Limit Safety Recommendations Exist
No adverse or toxic reactions to vitamin B12 have been reported from either dietary consumption or supplements. The US Food and Nutrition Board hasn’t set any upper safety limits for B12 in healthy individuals. While it’s always a good idea to consult your doctor before starting any new supplement, B12 supplementation is generally considered safe. If you’re looking for a safe and natural B12 supplement, I recommend Global Healing’s B12. It’s a vegan-friendly formula that contains methylcobalamin and adenosylcobalamin, as well as hydroxocobalamin for long-lasting support, with 5,000 mcg of B12 per serving. It even includes Energized Trace Minerals for better bioavailability.
Watch an in-depth video on everything you need to know about vitamin B12.
