Vitamin B12- Role, deficiency, diet and supplementation
- cdmkfitness
- Jan 5
- 6 min read
Updated: Mar 23
Vitamin B12 is a nutrient that helps keep your body's blood and nerve cells healthy and helps make DNA, the genetic material in all of your cells. Vitamin B12 also helps prevent megaloblastic anemia, a blood condition that makes people tired and weak.
A deficiency or insufficiency can occur when levels of vitamin B12 become too low to meet the demands of the body. This can lead to a number of symptoms and can even provitamin B12 is a water-soluble vitamin, like all other B vitamins. This means it can dissolve in water and travel through the bloodstream
Vitamin B12 is crucial to various bodily process;
Normal functioning of the brain and nervous system
Cognitive functioning (ability to think)
Formation of red blood cells & anemia prevention
Helping create and regulate DNA
Possibly preventing congenital abnormalities
Helping protects the eyes from muscular degradation
Necessary for energy production.
Vitamin B12 is essential for healthy blood. When the body does not have enough B12, it leads to decreased normal red blood cell production (anemia), which impairs oxygen delivery.
Megaloblastic anemia, also called nutritional deficiency anemia, is a type of anemia caused by B12 or folate deficiency. Megaloblastic anemia is characterized by impaired DNA synthesis and the formation of large, abnormal, immature red blood cells.
Intake requirement:
The National Institutes of Health (NIH) recommend that teens and adults over the age of 14 should consume 2.4 mcg of vitamin B12 daily. Pregnant people should consume 2.6 mcg, and lactating people 2.8 mcg.
Excessive intake of vitamin B12 has not shown toxic or harmful qualities. However, people should speak with their physician before starting any new supplements.
Some medications may decrease the absorption of vitamin B12 from foods. These medications include:
Metformin
Proton pump inhibitors
H2 receptor agonists, often used for peptic ulcer disease
Food Sources:
Vitamin B12 occurs naturally in many animal products. It does not typically occur in plant foods, unless it is supplemented.
Good dietary sources of vitamin B12 include;
Fortified cereals
Nutritional yeast
Fortified plant-based milks (soy, almond, oat)
Fortified tofu
Cheese (e.g., Swiss, mozzarella)
Yogurt
Liver (beef, lamb)
Shellfish (clams, crab, shrimp)
Fish (salmon, tuna, mackerel)
Eggs
Dairy (milk, cheese, yogurt)
Food Source | Serving Size | Vitamin B12 Content (µg) | % RDA for Adults (2.4 µg/day) |
Clams | 85 g (3 oz) | 84 µg | 3,500% |
Liver (Beef or Lamb) | 85 g (3 oz) | 70 µg | 2,917% |
Salmon | 100 g (3.5 oz) | 4.5 µg | 188% |
Tuna (Cooked) | 100 g (3.5 oz) | 2.5 µg | 104% |
Eggs | 2 large (100 g) | 1.1 µg | 46% |
Dairy (Milk) | 1 cup (240 ml) | 1.2 µg | 50% |
Cheese (Swiss) | 30 g (1 oz) | 0.9 µg | 38% |
Fortified Cereals | 1 serving (30 g) | 6 µg | 250% |
Nutritional Yeast | 1 tablespoon | 2.4 µg | 100% |
Fortified Plant Milk | 1 cup (240 ml) | 2-3 µg | 83-125% |
Some people are at an increased risk of developing B12 deficiency or insufficiency. Groups at an increased risk include:
Older adults
Those on restrictive diets like vegan diets
People with certain health conditions such as celiac disease.
Having low B12 levels can lead to a number of symptoms, some of which can be serious. It can result in irreversible and potential source damage, especially to the nervous system and brain. This, however, is uncommon.
Even slightly lower-than-normal levels of vitamin B12 can trigger symptoms. However, these symptoms are nonspecific and are not enough to diagnose vitamin B12 deficiency. Symptoms may include:
Depression
Confusion
Memory problems
Fatigue
headaches
mood changes
difficulty concentrating
Once symptoms worsen, they can include neurological changes, such as numbness and tingling in the hands and feet. Some people may have difficulty maintaining balance.
Infants who lack vitamin B12 may show;
Unusual movements, such as face tremors
Reflex problems
Feeding difficulties
Irritation
Eventual growth problems if left untreated
B12 deficiency has been linked to an increased risk of cognitive impairment & depression. Insufficient vitamin B12 can also lead to anemia. The most common symptoms of anemia are fatigue, shortness of breath, and an irregular heartbeat. People with anemia might also experience:
A sore mouth or tongue
Weight loss
Pale or yellowing skin
Diarrhea
Menstrual problems
Toxicity & Side Effects:
The overdose of oral supplements of vitamin B12 can lead to certain side effects in your body. These side effects commonly include/manifest as:
· Vomiting
· Diarrhea
· Nausea
· Headache
· Weakness
· Tiredness
· Tingling sensation or numbness in your extremities
Side Effects of Overdose of Vitamin B12:
Vitamin B12 supplements are also delivered as high-dose shots directly into your system thereby reducing its deficiency quickly. The side effects of Vitamin B12 are rare as these shots are prescribed by the doctor only when you have a deficiency. The overdose of vitamin B12 shots can commonly cause mild to severe side effects. These side effects include:
· Swelling
· Diarrhea
· Skin rashes
· Itching
· Muscle weakness or cramps
· Nausea
· Vomiting
· Headache
· Dizziness
· Leg pain
· Fatigue
· Frequent urge to drink water
· Increased urination
· Faster heart rate
Common Side Effects of Overdose of Vitamin B12
Some of the side effects of vitamin B12 are very common that may occur irrespective of the form in which you are taking vitamin B12 doses.
Skin Rashes
Skin rashes are one of the most common side effects of vitamin B12 overdose. You might find your skin flushed with the presence of welts all over your body. You might also feel itchiness in your entire body. The extent to which these skin rashes may appear on your skin depend upon the intensity of overdose of vitamin B12 in your body.
Gastrointestinal Problems
Gastrointestinal health issues are another major side effect of vitamin B12. These issues may range from mild to severe depending upon the extent of overdose. Some of the common vitamin B12 health issues include nausea, indigestion, and diarrhea. High doses of vitamin B12 can lead to severe diarrhea and intense stomach cramps in elderly people or people who have a history of gastrointestinal issues.
Insomnia
Insomnia refers to the inability to have a healthy and sound sleep. The overdose of vitamin B12 can worsen your existing problem of insomnia or might initiate insomnia as well by interrupting with your normal sleep cycle. This generally happens because vitamin B12 increases your energy levels that affect the normal sleep patterns ultimately leading to insomnia.
Numbness or Tingling Sensation
Long or prolonged intake of high doses of vitamin B12 can lead to numbness or tingling sensation which usually occurs in the right side of your body. The presence of a tingling sensation or numbness are one of the first signs of vitamin B12 overdose.
Mood Swings
The overdose of vitamin B12 can also affect the peace of your mind. It can lead to certain issues of mental health that may include restlessness, mood swings, panic attacks, and depression. The effect of vitamin B12 on mental health can worsen in people who naturally suffer from confusion, paranoia, or mental fogginess.
Sr. No. | Age | The daily requirement of vitamin B12 |
1. | 0 - 6 months | 0.4 mcg |
2. | 7 - 12 months | 0.5 mcg |
3. | 1 - 3 years | 0.9 mcg |
4. | 4 - 8 years | 1.2 mcg |
5. | 9 - 13 years | 1.8 mcg |
6. | 14 - 50 years | 2.4 mcg |
7. | Pregnant females | 2.6 mcg |
8. | Breastfeeding mothers | 2.8 mcg |
Which form of supplement should we taken
When to Supplement:
For those with deficiency symptoms (e.g., fatigue, tingling, memory issues).
Individuals unable to meet B12 needs through diet (vegans, elderly, those with malabsorption issues).
Best Form of B12 Supplements:
Cyanocobalamin:
Most stable and cost-effective form.
Widely used in supplements and fortified foods.
Suitable for general prevention of deficiency.
Methyl cobalamin:
Biologically active form.
Better for individuals with absorption issues or specific health conditions (e.g., neurological symptoms).
Hydroxocobalamin:
Injectable form.
Used for severe deficiencies or those unable to absorb B12 orally
Tablet- If a patient with Vitamin B12 deficiency finds that tablets do not support their recovery, there could be several reasons:
Possible Reasons:
Malabsorption Issues:
Pernicious Anemia: A condition where the body cannot produce enough intrinsic factor (a protein needed to absorb B12).
Gastrointestinal Disorders: Conditions like Crohn’s disease, celiac disease, or a history of gastric surgery can impair absorption.
Low Stomach Acid (Hypochlorhydria): Common in elderly patients, leading to reduced B12 release from food or supplements.
Dosage or Form of Supplement:
Tablets might not have sufficient bioavailability, or the patient may not tolerate the specific form of B12 (cyanocobalamin vs. methyl cobalamin).
Compliance Issues:
Irregular intake or improper administration (e.g., not taken with meals) might reduce effectiveness.
Competing Nutritional Deficiencies:
Deficiencies in other nutrients like folate or iron can hinder the full utilization of B12.
Genetic Factors:
Variants in genes like MTHFR can affect how the body processes B12 and folate.
Takeaway
Vitamin B12 is an essential part of your daily dietary requirements. The deficiency, as well as excess of vitamin B12, can disrupt the normal functioning of the human body leading to certain health complications. Therefore, you must ensure that you include vitamin B12 in your diet either through food sources or supplements. Now that you know the common side effects of vitamin B12 supplements and the daily requirement of vitamin B12, make sure that you take vitamin B12 in the right amount and only when they are prescribed to you by a doctor. Vitamin B12 is essential but its overdose can cause more harm than good. So it is advisable to get your vitamin B12 levels tested before you start taking its supplements.
References
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