Bariatric Vitamin Guide

By Derek

Everyone knows that taking vitamins benefits your health. However, it is less often known why this is true. In order to function properly, your body needs the correct balance of vitamins and minerals. These vitamins not only help to regulate some of the body’s most important processes, they also have an impact on weight. Vitamins regulate brain activity, hunger, appetite, nutrient absorption, energy storage, and metabolic rate, which all directly affect body weight.

While foods are the best sources of vitamins and minerals, sometimes it is difficult to get everything your body needs into your diet. This is especially true for those who have undergone bariatric surgery. Because not everyone is able to get all of the nutrition needed from their diet, medical research has found the specific vitamins that are essential for the body and created supplements to help.

Bariatric surgery dramatically decreases the body’s ability to absorb vitamins and nutrients and/or restricts the amount of food you can consume.  This results in malnutrition, or vitamin and mineral deficiencies, that can be detrimental to your health.

Vitamins and minerals are needed after surgery so the body can heal properly. They also regulate the metabolism and help convert calories into energy. Unlike carbohydrates, protein, and fat, vitamins and minerals are only needed in small doses.

The body needs minerals to create bodily fluids, maintain healthy teeth and bones, make healthy blood, and regulate vital functions such as nerve and heart functions. Here are some specific vitamins and minerals that are needed after bariatric surgery.

Vitamin A

Vitamin A, essential for overall good health, promotes growth, the immune system, reproduction, and vision. The two most common sources of Vitamin A are retinol and beta-carotene.

Retinol is found in animal foods such as liver, eggs, and fatty fish.  It can also be found in many fortified foods.  Beta-carotene is found naturally in most orange and dark green plant foods – think carrots, sweet potatoes, and kale.

How much Vitamin A do you need?

The ASMBS recommends 10,000 IU per day of Vitamin A.

B1 (Thiamine)

The body does not store Thiamine; therefore it needs to be consumed each day. Thiamine is essential for the conversion of food into energy. It is also essential for brain function and nerve function.

Thiamine deficiency is very possible in bariatric patients and it is a complication that can have serious or even permanent side effects. Some extra factors that increase the risk of a bariatric patient to a Thiamine deficiency include:

  • An increased occurrence of vomiting
  • A drastic restriction in energy intake
  • High carbohydrate intake through artificial feeding

How much B1 (Thiamine) do you need?

The ASMBS recommends 3mg per day of B1 (Thiamine). 

Vitamin B12

A vitamin B12 deficiency is the most common deficiency among people who have undergone bariatric surgery. While about 5% of patients have this deficiency prior to surgery, about 13% have it once surgery is complete. The B12 deficiency tends to occur due to the inadequate digestion of vitamin B12.

B12 plays a vital role in nervous system functioning and the growth and replication of cells. Potential complications from having a deficiency in vitamin B12 include:

  • Heart palpitations
  • Shortness of breath
  • Lightheadedness
  • Pale skin
  • Loss of appetite
  • Diarrhea
  • Vision loss
  • Memory loss
  • Depression

Bariatric patients are more likely to develop a vitamin B12 deficiency than other people because their digestive tracts have been changed. This causes an interference with the natural absorption of B12. In adults who have not undergone bariatric surgery, the body uses stomach acid to break down vitamin B12, which lets it get absorbed into the body.

How much B12 do you need?

The ASMBS recommends 1000mcg per day of B12. 

Vitamin C

Vitamin C should be taken to promote the healing of the wounds created during surgery. A deficiency in vitamin C can lead to the failure of the tissues in the body to repair themselves. A deficiency may also lead to:

  • Easy bruising
  • Gum disease
  • Slow wound healing
  • Rough, dry, scaly skin
  • Dry and splitting hair
  • Swollen and painful joints
  • Weakened immune system

Low levels of vitamin C have also been associated with high blood pressure, stroke and the build up of plaque in blood vessels leading to heart failure.

How much Vitamin C do you need?

The ASMBS recommends 120 mg per day of Vitamin C. 

Calcium Citrate

Calcium is a mineral found in a variety of foods and is a key player in the maintenance and development of strong bones and healthy teeth.  It also facilitates healthy muscle and brain function. There are two main forms of calcium supplements available: calcium citrate and calcium carbonate. It is very important that bariatric patients use nutritional supplements that their systems are able to absorb easily, especially Calcium Citrate, which is designed for altered digestive systems. Without Calcium Citrate, bariatric patients may experience a deficiency that could lead to long-term complications and compromised health.

How much calcium do I need?

The ASMBS recommends 1,200 mg of calcium per day for gastric bypass and vertical sleeve patients, and 2,400 mg of calcium per day for duodenal switch patients.

Vitamin D3

Vitamin D promotes bone and cell growth and reduces inflammation. This is very important to the healing of bariatric patients. Symptoms of vitamin D deficiency are frequent bone fractures, fatigue, and muscle weakness. Vitamin D is especially vital to take because often you will not show symptoms of being deficient until your levels are dangerously low.

Vitamin D can be taken as a supplement and especially needs to be taken if you are not spending any time in the sun. Sun exposure helps the body to create vitamin D on its own, and it is not found naturally in many foods. Because a bariatric patient’s diet is very limited anyway, it is important to make sure sufficient amounts of vitamin D are consumed.

How much Vitamin D3 do you need?

The ASMBS recommends 3,000 to 6,000 IU per day of Vitamin D3. 

Folate (also known as B9 or Folic Acid)

Folate is one of the building blocks that is necessary for all human cells to grow. It creates red blood cells and neurons. Folate can be found in various foods, including:

  • Bread
  • Cereal
  • Flour
  • Pasta
  • Rice
  • Legumes
  • Lean meats
  • Eggs
  • Nuts
  • Seeds
  • Soy products

Folate deficiencies may lead to several problems, including anemia and various psychiatric and neurologic problems. Processes such as bariatric surgery that interfere with the intestinal wall can prohibit folate absorption.

How much Folate do you need?

The ASMBS recommends 400mcg per day of Folate. 


Iron is an essential nutrient found in vegetables and red meat. Although it is unclear exactly how iron is absorbed, the small intestine appears to play a large role in the process. Because bariatric surgery may interfere with iron absorption, it is important for patients to take an iron supplement to avoid becoming anemic.

How much Iron do you need?

The ASMBS recommends 40-60mg per day of Iron.

Vitamin K

Vitamin K is a fat-soluble vitamin that plays an integral role in blood clotting and bone health. What is alarming is that most bariatric specific multivitamins completely omit vitamin K! Cases of vitamin K deficiencies in adults with unaltered intestinal tracts is rare; however, for those who have undergone bariatric surgery, the intestinal tract is altered.

IMPORTANT: Vitamin K can affect how blood-thinning drugs, like Coumadin (warfarin), work.  It is important that you address this with you surgeon and/or dietitian if you are currently prescribed anticoagulant or antiplatelet drugs before engaging in a vitamin regimen that contains high levels of vitamin K.

How much Vitamin K do you need?

The ASMBS recommends 160 mcg per day of vitamin K. 


According to the Harvard School of Public Health, taking a daily multivitamin is similar to having an insurance policy. It will fill in the gaps where your diet is lacking in micronutrients. Multivitamins are available in tablets and powder, and should be taken according to the package directions.

This is especially important for bariatric patients because their diet is destined to be lacking. There will be a great drop in the amount of food that is consumed, leaving a larger area of nutrition uncovered by the daily diet. Taking a multivitamin will at least help to cover the bases on anything you may be missing.

ASMBS Guidelines

The American Society for Metabolic and Bariatric Surgery is the largest national society for metabolic and bariatric surgery. The Society strives to improve public health by lessening the burden of obesity and related diseases around the world.

Your surgeon will provide you with a nutritional plan after your surgery. This will likely consist of a liquid diet before slowly reintroducing small amounts of soft food. Staying hydrated during the healing period helps patients avoid constipation and kidney stones. Your daily supplemental regimen to follow for the rest of your life typically includes a multivitamin, Calcium, Vitamin D, Iron, and Vitamin B12. Your doctor will recommend the dosages that are right for you.

Making healthy lifestyle choices moving forward is vital to maintaining the best health and quality of life. A diet that is high in protein and low in carbohydrates, especially low in simple carbohydrates, is ideal. Avoid sugar and processed foods as much as possible. Once you are eating whole foods again, stick to lean protein, fruits, and vegetables to keep your fiber and vitamin intake sufficient.

Bariatric surgery patients especially need a good quality vitamin and mineral each day for the rest of their life. It is also important to take any supplements that are recommended for you in particular. Although the specific amounts of supplements can vary from person to person, bariatric surgeons and dietitians both firmly agree that taking supplements is necessary to prevent malnutrition following bariatric surgery.

It is essential for bariatric surgery patients to have their vitamin and mineral levels checked regularly after surgery. This may include a multidisciplinary team, consisting of a dietician, a primary care physician, a gastroenterologist, as well as nursing staff to make sure that complications due to malnutrition following surgery are limited. Together, teams of doctors along with consensus guidelines can help provide better nutritional care to patients who have undergone bariatric surgery.

Bariatric Vitamin Guide


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What are your tips and tricks to post-bariatric success?

Share your thoughts or questions in the comments below – we want to hear from you!


  1. What is a good vitamin that has everything we need, and won’t break the bank every month…

  2. I got B12 deficiencies after gastric bypass surgery. Is it necessary to take B12, my doctor recommend Eligen B12 any guys know about this?

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