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Why do I need to take multi vitamins after bariatric surgery?

Do I need to take multi vitamins after bariatric surgery? Why do I need to take multi vitamins? These are questions I get asked a lot by patients who are either considering or have had bariatric surgery. The first question is always the simplest to answer, because it’s always yes. The second tends takes a little bit longer to answer, because I need to explain:

Do I need to take multi vitamins after bariatric surgery?
Why do I need to take multi vitamins?

These are questions I get asked a lot by patients who are either considering or have had bariatric surgery. The first question is always the simplest to answer, because it’s always yes. The second tends takes a little bit longer to answer, because I need to explain:

  1. What happens after bariatric surgery?
  2. What are micronutrients /vitamins?
  3. What they do?
  4. What happens when we don’t take them?
What happens after bariatric/weight loss surgery?

Weight loss surgery (WLS), including sleeve gastrectomy (SG),and Roux-en-Y gastric bypass (RYGB), dramatically alters your intake, digestion, and absorption of both macronutrients (protein, carbohydrates, and fats) and micronutrients (vitamins and trace elements). While the goal of surgery is to decrease caloric intake in an effort to lose weight, these operations can also result in significant nutritional deficiencies that may lead to severe complications.

So, what are micronutrients?

Micronutrients are one of the major groups of nutrients your body needs. They include both vitamins and minerals. Vitamins are necessary for energy production, immune function, and blood clotting. While minerals play an important role in growth, bone health, and fluid balance.

Our bodies cannot produce micronutrients so we must obtain vitamins and minerals from our food. Which is why they’re also referred to as essential nutrients. Vitamins are made by plants and animals, while minerals are inorganic, and are present in the soil or water. As a consequence, when you eat a plant or animal you consume the vitamins they have created or the minerals they have absorbed.

An adequate intake of all micronutrients is necessary to be healthy, as each vitamin and mineral has a specific role in your body.

Vitamins and minerals are divided into four categories: water-soluble vitamins, fat-soluble vitamins, macro minerals and trace minerals.

What do they do?

Water-soluble vitamins

Most vitamins dissolve in water and are therefore known as water-soluble, however they’re not easily stored in our bodies. They each play a unique role, but their functions are related.

There are nine essential water-soluble vitamins which consist of the eight “B” vitamins and vitamin C.

  • Vitamin B1 (thiamine): Helps convert nutrients into energy.
  • Vitamin B2 (riboflavin): Is need for cell function, energy production, and fat metabolism.
  • Vitamin B3 (niacin): promotes the production of energy from food.
  • Vitamin B5 (pantothenic acid): Necessary for fatty acid synthesis
  • Vitamin B6 (pyridoxine): Helps your body release sugar from stored carbohydrates for energy and create red blood cells
  • Vitamin B6 (pyridoxine): Helps your body release sugar from stored carbohydrates for energy and create red blood cells.
  • Vitamin B7 (biotin): Is important for the metabolism of fatty acids, amino acids and glucose.
  • Vitamin B9 (folate): Important for cell division.
  • Vitamin B12 (cobalamin): Necessary for red blood cell formation and proper nervous system and brain function.
  • Vitamin C (ascorbic acid): needed to make neurotransmitters and collagen, the main protein in your skin.

What happens when we don’t take them?

Most of the water-soluble vitamins are not associated with any clinically significant deficiencies following bariatric surgery. The exceptions are thiamine, vitamin B12, and folate deficiencies after WLS which can lead to serious, life threatening, and potentially irreversible complications.

Thiamine (Vitamin B1)

Thiamine deficiency is one of the, if not the, most serious nutritional deficiencies following bariatric surgery. Thiamine has a relatively short half-life (~10– 20 days) which means that it doesn’t last very long in our bodies, so deficiencies can occur in a matter of weeks. Thiamine is predominantly absorbed in the duodenum and proximal small bowel, and thus, patients having operations such as RYGB are at the highest risk. Thiamine deficiency cause potentially irreversible life-threatening cardiovascular and neurologic complications such as:

  • Wet beriberi, which affects the heart and circulatory system. In extreme cases, it can cause heart failure.
  • Dry beriberi damages the nerves and can lead to decreased muscle strength and eventually, muscle paralysis.
  • Wernicke’s encephalopathy can result in confusion and loss of muscle coordination(ataxia). It can progress to coma and death.
Vitamin B12

Vitamin B12 deficiency can be seen after both SG, and RYGB. It’s stored in the liver can last 3–5 years, and therefore deficiency may take several years to develop without appropriate supplementation.

Manifestations of B12 deficiency include:

  1. Megaloblastic anaemia: where your red blood cells that are larger than normal, and there aren’t enough of them to carry oxygen properly.
  2. Infertility.
  3. Glossitis: inflammation of your tongue.
  4. Paraesthesia: abnormal sensation of your skin tingling, pricking, chilling, burning, numbness
  5. Autonomic dysfunction: autonomic nervous system is damaged. This is the system of nerves that controls functions that help you survive.
  6. Ataxia.
  7. Cognitive decline.

Folate, also referred to as folic acid, or vitamin B9, Unlike B12, very little folic acid is stored in the body, and constant intake is required to maintain adequate levels in your body. Therefore, not taking enough folate can lead to a deficiency in just a few weeks. Folate deficiency can cause anaemia, which is a condition in which you have too few RBCs. This can deprive your tissues of oxygen it needs because RBCs carry the oxygen. Folate is particularly important in women of childbearing age, and a deficiency during pregnancy can lead to birth defects.

Fat-Soluble Vitamins

Fat-soluble vitamins do not dissolve in water. They’re best absorbed when eaten alongside a source of fat. They are stored in your liver and fatty tissues for future use.

The names and functions of fat-soluble vitamins are:

  • Vitamin A: is needed for proper eye site and organ function
  • Vitamin D: promotes proper immune function and helps in calcium absorption and bone growth
  • Vitamin E: assists immune function and helps to protect your cells from damage
  • Vitamin K: is needed for your blood to clot properly and for bone development

Fat-soluble vitamins (vitamins A, D, E, and K) are commonly deficient following malabsorptive procedures such as Gastric bypass surgery.

What happens when we don’t take them?

Vitamin A

Vitamin A deficiency causes problems with your eyesight. These include night blindness, decreased visual acuity, dry eyes and can cause permanent blindness if left untreated.

Vitamin D

Vitamin D deficiency may lead to increased bone resorption. This phenomenon, also known as metabolic bone disease, most commonly affecting the hips and spine, and may cause:

  • Osteopenia: the inside of your bones become brittle from the loss of calcium and your bones get weaker and can lead to osteoporosis.
  • Osteoporosis: causes bones to become so brittle that a fall or even mild stresses such as bending over, or coughing can cause a fracture.
  • Osteomalacia: softening of your bones.
Vitamin E

Vitamin E deficiency is characterized by damage to the retina at the back of your eye, ataxia, loss of awareness of the position of your joints and movements, and myopathy (muscle weakness), and impaired immune response.

Minerals and Trace Elements

The two essential minerals that are frequently deficient following weight loss surgery are calcium and iron. Other important trace elements are zinc, copper, and selenium.

  • Calcium: Necessary for the normal structure of your bones and teeth. Helps with muscle function and blood vessel contraction.
  • Phosphorus: Part of bone and cell wall structure.
  • Magnesium: helps over 300 enzyme reactions, including regulation of blood pressure.
  • Sodium:  helps proper fluid balance and blood pressure control.
  • Potassium: helps maintain fluid status in cells and your nerves and muscles function normally.
  • Sulphur: Part of every living tissue and contained in the amino acids methionine and cysteine.
  • Iron: Helps provide oxygen to muscles and assists in the creation of certain hormones.
  • Manganese: Assists in carbohydrate, amino acid and cholesterol metabolism .
  • Copper: Required for connective tissue formation, as well as normal brain and nervous system function.
  • Zinc: Necessary for normal growth, immune function and wound healing.
  • Iodine: Assists in thyroid regulation.
  • Selenium: Important for thyroid health, and reproduction

What happens when we don’t take them?


Calcium is required for your cells to work normally. The absorption of calcium is mainly in the duodenum and beginning of your small intestine. Following bariatric surgery, calcium and vitamin D are two of the most common nutrient deficiencies. 

What happens if your calcium gets too low?

  • Decreased heart muscle strength and heart rate,
  • Hypotension: low blood pressure,
  • Paraesthesia,
  • Muscle cramps, and
  • Bone diseases such as: osteoporosis (your bones to become thinner and weaker than normal) or osteomalacia (softening of your bones)

Iron is essential for the production of haemoglobin, and therefore iron deficiency results in an anaemia. Iron deficiency has been seen in up to 44% of patients presenting for bariatric surgery and is one of the most common nutrient deficiencies following gastric bypass surgery.

The risk of iron deficiency is increased in menstruating or pregnant women.

Signs and symptoms of iron deficiency include:

  • Fatigue
  • Depression
  • Light-headedness
  • Hair loss
  • Weakness

Can I take any Multivitamin?

The simple answer is no.

Over the counter brands are designed for people who need a ‘top up’ and have an intact GI tract, and do not meet the increased requirements of those who have had WL surgery described above.

You will need to take multivitamin supplement that has been specifically designed to meet the increased needs of the bariatric patient such as:

Celebrate brand has been well established after bariatric surgery, including:

  • 2 x Celebrate multivitamin capsules (with or without iron) or
  • 1-2 x Celebrate multivitamin soft chew

Which can be purchased at

  • Barilife once a day single multivitamin (with or without iron)
  • Baribursts chewable calcium citrate.
  • Complete Bariatric Multivitamin Powder

These can be purchased at

  • 1 x centrum for women/men/50+ taken twice a day purchased from your supermarket. You will also need to take calcium supplementation.

You will also need to take a sublingual B12 (that dissolves under the tongue) or you can have an intramuscular B12 injection every 3 months.

Do I have to take them every day?

Yes.  Multivitamins are required to be taken every day for life, no matter what stage after surgery you are.

…You will need to take multivitamin supplement that has been specifically designed to meet the increased needs of the bariatric patient

Mark Grant
Mark Grant
Helen Gibbs - Our Dietician
Helen Gibbs

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