Vitamin B12: How much is too much?

As such, we reached out to experts to understand the role of vitamin B12, its deficiency, and whether it is possible to overdose on supplements or injections.

What is vitamin B12?

According to Mayo Clinic.org, vitamin B12 (cobalamin) plays an essential role in the formation of red blood cells, cell metabolism, nerve function and the production of DNA. Cobalt-containing compounds with vitamin B12 activity are referred to as cobalamin. The metabolically active forms of vitamin B12 are methylcobalamin and 5-deoxy adenosylcobalamin. However, two other forms — hydroxocobalamin and cyanocobalamin — become biologically active after they are converted to methylcobalamin or 5-deoxy adenosylcobalamin, said Dr Aravinda G M, consultant, internal medicine, Manipal Hospital, Jayanagar, Bangalore.

Vitamin B12 deficiency

Having trouble absorbing vitamin B12 from food, lacking intrinsic factors (for example, as a result of pernicious anaemia), having gastrointestinal surgery, taking certain medications for an extended period of time (such as metformin or proton pump inhibitors), and nutritional deficiencies are all causes of vitamin B12 deficiency.

According to Dr Aravinda, congenital diseases include Immerslund-Gräsbeck illness, which causes severe vitamin B12 insufficiency, and genetic intrinsic factor abnormalities which can both lead to severe vitamin B12 deficiency.

Vitamin B12 foods are plenty (Source: Getty Images/Thinkstock)

If you don’t get enough vitamin B12, you could get anaemia. The symptoms are:

Low energy
Chronic fatigue
Weakness
Light-headedness
Heart palpitations and shortness of breath
Pale skin
Dental problems, such as mouth sores and bleeding gums
Sore red tongue
Yellowing of the skin
Mouth ulcers
Constipation, diarrhoea, nausea, loss of appetite, or gas
Nerve issues such as tingling or numbness, muscle weakness, and difficulty walking
Joint pain
Vision loss
Mental illness, memory loss, or behavioural changes
Poor concentration

Dr Aravinda further noted that serious clinical symptoms like dementia, weariness, mood disruption, and megaloblastic anaemia can result from severe vitamin B12 insufficiency. “Serious neuropsychiatric and neurological problems can develop, if left untreated. A higher risk of myocardial infarction and stroke has also been associated with vitamin B12 deficiency. Some of these symptoms can also happen in people who have a vitamin B12 deficiency but have not developed anaemia,” said Dr Aravinda.

Treating vitamin B12 deficiency

Vitamin B12 injections are typically used to treat anaemia caused by vitamin B12 deficiency. There are 2 types of vitamin B12 injections:

• Hydroxocobalamin
• Cyanocobalamin

The choice that stays in the body longer, hydroxocobalamin, is typically advised, said Dr Aravinda. “These injections will initially be administered every other day for two weeks, or until your symptoms start to subside. After the initial phase, your treatment will depend on whether your vitamin B12 shortage is caused by your food or whether it is resulting in any neurological issues, such as issues with thinking, memory, and behaviour,” Dr Aravinda commented.

Oral supplement: To enhance vitamin B12, choose high-dose oral supplements. Evidence suggests that increasing vitamin B12 levels in patients with deficiencies with high-dose oral supplementation at 1000mcg is a successful tactic. In addition, oral supplementation is associated with significant cost savings, no side effects and increased compliance, compared to intramuscular injections.

Diet-related: If your vitamin B12 deficiency is caused by a lack of vitamins in your diet, you may be prescribed vitamin B12 tablets to take every day between meals. Alternatively, you may need hydroxocobalamin injections twice a year. People who find it difficult to get enough vitamin B12 in their diets, such as those following a vegan diet, may need vitamin B12 tablets for life. Less commonly, people with vitamin B12 deficiency due to long-term poor diet may be advised to stop taking the pill once vitamin B12 levels have been restored to normal and their diet has improved.

Good sources of vitamin B12 include:

• Meat
• Fish like Salmon
• Milk and other dairy products
• Eggs

If you’re a vegetarian or vegan, or are looking for alternatives to meat and dairy products, there are other foods that contain vitamin B12, such as yeast extract, as well Like fortified breakfast cereals and soy products, Dr Aravinda shared.

So, is there a concern about overdose?

Vitamin B12 supplements are generally considered safe when taken in appropriate dosages. The recommended daily dose of vitamin B12 for adults is 2.4 micrograms, but higher doses have been shown to be safe. The body takes in as much as it needs and the excess is excreted in the urine, Dr Aravinda said.

Rather than diet or oral supplements, an overdose of B12 is majorly caused due to high doses of injection, said (Ms) Roshan Kore, senior dietitian and nutritionist, SRCC Children’s Hospital, managed by Narayana Health (Haji Ali, Mumbai).

Overdose of B12 can cause anxiety, acne, skin redness, headache, nausea, vomiting, heart stroke, face paralysis, palpitations, facial ruddiness, and insomnia. “Patients with existing diabetes or kidney disease can have more adverse effects like further reducing the kidney function. Pregnant women having extremely high B12 levels due to overdose increases the risk of autism spectrum disorder in their unborn child,” Dr Kore told indianexpress.com.

Deficiency, as well as overdose, can lead to issues for you (representative) (Source: Getty Images/Thinkstock)

According to Dr Aravinda, high doses of vitamin B12 used to treat deficiency can cause:

Headache
Nausea and vomiting
Diarrhoea
Fatigue or weakness
Tingling sensation in hands and feet

Dr Aravinda further commented that possible interactions with other drugs include

• Aminosalicylic acid. Taking this drug to treat digestive problems may reduce the body’s ability to absorb vitamin B12.
• Colchicine. Taking this anti-inflammatory drug to prevent and treat gout attacks may reduce the body’s ability to absorb vitamin B12.
• Metformin. Taking this diabetes drug might reduce your body’s ability to absorb vitamin B12.
• Proton pump inhibitors. Taking omeprazole, lansoprazole or other stomach acid-reducing drugs might decrease your body’s ability to absorb vitamin B12.
• Vitamin C (ascorbic acid) supplements. Taking vitamin B12 along with vitamin C can reduce the amount of vitamin B12 available in the body. To avoid this interaction, take vitamin B12 supplements before taking Take vitamin C at least 2 hours later.

How to treat overdose?

Kore said that the toxicity of vitamin B12 can be treated by giving more hydration orally or through an IV line, depending upon the severity of the symptoms.

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