Here's Why You Should Prioritize B1 & B12 after Surgery

Article By: Rachel Ignomirello, MS, RDN, CSOWM, LDN

Rachel Ignomirello is a Bariatric Dietitian and Board-Certified Specialist in Obesity and Weight Management.

For patients who have undergone bariatric surgery, vitamin and mineral supplementation is a MUST. Patients hear all the time about how important it is to take their vitamins. This lifelong commitment keeps patients healthy and prevents serious deficiencies. Some of the most important vitamins are the B-Vitamins, which include Vitamins B12 and Thiamin (B1).

1) What is Vitamin B12?

Vitamin B12 (cobalamin) is a water-soluble micronutrient that helps form the body’s red blood cells, keep nerve cells healthy, produce DNA (the genetic material in cells), and much more. Our bodies cannot make B12 on their own.

B12 is found naturally in foods, mostly animal-based foods like fish, meat, poultry, and dairy. However, the top three food sources include beef liver, clams, and nutritional yeast. When these foods are consumed, the hydrochloric acid in the stomach removes the B12 from the food. Then, the B12 combines with a protein called "intrinsic factor" before being absorbed by the digestive system.

2) How is B12 impacted by bariatric surgery & what are the deficiency signs/symptoms?

B12 deficiency is one of the most common deficiencies in the bariatric population. Beyond the reduced food source intake, absorption is also impacted after surgery. There is less stomach (hydrochloric) acid and intrinsic factor being produced. Intrinsic factor is made by cells in the stomach lining. Surgical removal or bypass of the stomach will reduce the production of intrinsic factor, which risks B12 deficiency (also called pernicious anemia).

The most common deficiency sign is fatigue or weakness. Patients may also present with GI issues (nausea or diarrhea), poor appetite and weight loss, sore mouth/tongue, paleness or yellowing of the skin, numbness or tingling in hands and feet, confusion, difficulty speaking, poor gait (walking), poor memory, etc.

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3) How much & how often should you take B12?

The Recommended Dietary Allowance (RDA) for B12 is 2.4 mcg per day for adults. There have practically been no toxic effects of excess B12. Per The American Society for Metabolic and Bariatric Surgery (ASMBS), the recommended prevention doses for bariatric patients include these options:

  • Daily: 350-500 mcg oral disintegrating tablet, sublingual, or liquid
  • Weekly: Nasal spray, typically 500 mcg spray in one nostril
  • Monthly: 1,000 mcg, intramuscular or subcutaneous injection

4) What is Thiamin?

Thiamin (Vitamin B1) is a water-soluble micronutrient. It is important for the body’s cell growth, development, and function. It also plays a role in carbohydrate metabolism, which helps the body turn food into energy. The body does not store Thiamin, so it must be consumed daily.

Thiamin is found naturally in foods like meats (pork), fish, legumes (beans), nuts, seeds, whole grains, and fortified grains like bread, cereal, pasta, and rice. The top five food sources of Thiamin are fortified breakfast cereals, enriched egg noodles, bone-in pork chops, trout, and black beans.

5) How is Thiamin impacted by bariatric surgery & what are the deficiency signs/symptoms?

Besides the reduced intake from food, Thiamin is also impacted by surgical resection. This vitamin is absorbed primarily in the small intestine, which may be bypassed following bariatric surgery. After surgery, nausea and vomiting can be common side effects. Thiamin deficiency risk increases with each episode of intractable (uncontrolled) vomiting. Thiamin deficiency is also seen in rare cases when a patient requires enteral tube feeding or total parental nutrition through the vein.

Thiamin deficiency can cause poor appetite, confusion, muscle weakness, and heart problems. It impairs oxidative metabolism, which can lead to inflammation and neurodegeneration. The most common deficiency is Wernicke-Korsakoff syndrome, which is a neurological disorder caused by the lack of Thiamin. It often affects people with alcoholism and can lead to severe memory loss, disorientation, and confusion. Severe Thiamin deficiency leads to a disease called beriberi. Symptoms include numbness and tingling in hands and feet, muscle loss, poor reflexes, edema, and potential death. This is more common in underdeveloped nations.

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6) How much & how often should you take Thiamin?

The Recommended Dietary Allowance (RDA) for Thiamin is 1.1 mg/day for women and 1.2 mg/day men. Per The American Society for Metabolic and Bariatric Surgery (ASMBS), daily recommended prevention dose options include:

  • All postoperative patients should take at least 12 mg Thiamin daily to maintain blood levels
  • High-risk patients should take 50-100 mg Thiamin daily. At-risk patients include rapid weight loss, recurrent vomiting, parenteral nutrition, excessive alcohol, neuropathy, encephalopathy, and/or heart failure.

7) Can you take B-Vitamins together? Before bedtime?

Yes and yes. There are no timing interactions with Vitamins B12 and Thiamin. I’ve had the rare patient who had difficulty sleeping when taking their B-Vitamins around bedtime, but the majority do well.

BariMelts provides general recommendations, not to be construed as medical advice. Please consult your doctor.

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