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The Essential Guide to Gastric Sleeve and Gastric Bypass Nutrition

Nutritional supplements after bariatric surgery

Supplements after surgery

It’s been found that even prior to bariatric surgery, many people have one or more micronutrient (vitamin or mineral) deficiencies,1 and the risk of a nutrition deficiency increases with time after surgery. This happens for several reasons:2

  • Inadequate nutrient intake, often due to a lower intake of food
  • An altered or decreased ability to absorb vitamins and minerals
  • An increased need for certain vitamins and minerals

One thing that many healthcare practitioners agree on is that all patients after surgery should take vitamin and mineral supplements for life.

Because of this, there are several published bariatric guidelines that help healthcare practitioners guide you in selecting which supplements you need after surgery. 3,4

All vitamins and minerals play an important role in the body and are needed in adequate amounts for general health and wellbeing. Bariatric patients need larger doses of vitamins and minerals than the general public. Below, we review some key nutrients that are recommended in much higher amounts post-surgery.

Important vitamins to take after Bariatric Procedures

The American Society for Metabolic and Bariatric Surgery (ASMBS), the largest nonprofit medical organisation dedicated to metabolic and bariatric surgery and obesity-related diseases and conditions, recommends vitamin and mineral supplementation following bariatric surgery to prevent nutritional deficiencies.3,4 Here are some of their suggestions below:

Vitamin D

Vitamin D is a fat-soluble vitamin found in very few foods; however, it is produced in the body when ultraviolet rays from the sun hit the skin. Despite this, vitamin D is the number one reported micronutrient deficiency before and after surgery. Vitamin D is often referred to as a hormone, based on how it functions within the body and its broad array of health effects. Vitamin D is well known for bone health as it support calcium absorption, but it is also critical for immune system function, muscle health and neurological health.

The ASMBS recommends an oral intake of at least 3000 IU (75 mcg) per day in the active form, Vitamin D3.

Fat Soluble Vitamins

Gastric sleeve patients taking multivitamin supplement after surgery

In addition to vitamin D, other fat soluble vitamins including Vitamins A, E and K may also be deficient, as following surgery there may be a delayed mixing of dietary fat with the pancreatic enzymes and bile salts that help break it down and absorb it. Dietary fat carries these vitamins into the body, so if fat absorption is impaired so too is the absorption of these critical nutrients. Vitamin A is particularly important for eye health. Vitamin K is important for bone health and healthy blood coagulation, while vitamin E is an antioxidant that protects skin and heart health.

The ASMBS recommends and oral intake of: 5,000 IU–10,000 IU (1,500 mcg–3,000 mcg) per day of vitamin A, 15 mg (16.7-22.4 IU depending on form of vitamin E), and 90 – 300 mcg of vitamin K. A well-formulated multivitamin and mineral formula can enable you to meet these vitamin requirements.

B Vitamins

The good news is Vitamin C deficiency is rare following bariatric surgery, unfortunately, deficiencies in other water-soluble vitamins such as certain B vitamins is quite common. Specifically, vitamin B1, B12 may require repletion through supplementation as the areas of the gastrointestinal tract through which they are absorbed are often affected by bariatric procedures. Folate is another B vitamin where supplementation is often recommended. The recommendation for folic acid is roughly 400 mcg/day, whilst thiamin (B1) is recommended in a range from 12-100 mg per day depending on other dietary sources, and B12 range also varies and can go as high as 500 mcg per day if an individual’s blood tests results show deficiency states.


Calcium is the most abundant mineral in the body and is found primarily in dairy food sources, but also in dark green vegetables like broccoli and kale. Like vitamin D, calcium is needed for bone structure and function, but it is also involved in other bodily processes such as the contraction and dilation of blood vessels, muscle function, nerve transmission, and hormonal secretion. Very few obvious clinical signs occur with calcium deficiency as the body controls blood levels of calcium; the most obvious signs of calcium deficiency occur long-term as bone breakage. However, it takes time for these symptoms to become obvious. By the time symptoms arise they may be very difficult to reverse. In the case of calcium deficiency, prevention is certainly easier than cure.

The ASMBS recommends a daily intake of 1200-2400 mg in bariatric patients, through a combination of dietary and supplemental sources. Remember, calcium is best taken in divided doses with an upper limit of 500 mg per serve so as to maximise its absorption.

Other Minerals

There are several other minerals that often require a supplemental top up. Iron for example, which is critical for red blood cell production and carrying oxygen around the body to create energy is commonly below the recommended daily intake for a number of patients. Zinc which is needed by the immune system to fight infection and for healthy skin and nails is also commonly depleted. These minerals often require a simple top up in the form of a multivitamin-mineral formula.

The ASMBS recommends a daily intake of 18-60 mg of iron in bariatric patients, though it is important not to overdose on iron so this is best achieved through a combination of diet and supplements and routine blood work can help ensure levels remain in a healthy range.  Zinc is recommended in doses of 8-22 mg per day, and is always best taken with food when in supplement form. 

Tips for Choosing a Bariatric Vitamin and Mineral Supplement

TIP 1: Know your appropriate nutrient dose

Specific doses of vitamins and minerals are recommended after surgery to prevent a micronutrient deficiency. Use the guidelines above to ensure you are taking the right dose of the right nutrient. Doses vary depending on procedure type, gender, and other factors. Your healthcare practitioner can help guide you to determine the level you should take specific to your individual requirements.

TIP 2: Choose a trusted brand that guarantees what is on the label is actually what is inside the bottle

Australian-made supplements must comply with some of the strictest manufacturing regulations in the world – meaning they are renowned for their quality. That said, there can still be great differences in the level of scrutiny different manufacturers apply to the development and manufacture of their supplements. Check with the manufacturer regarding their quality processes. Here are some standards to look for:

Scientific formulations: Does the company have a robust research and development team and quality assurance team that can ensure products are scientifically validated, suited to the population (in this case bariatric patients) and of the highest possible quality? Do their resources refer to scientific references to back up their claims?

Comprehensive testing: What kind of testing is performed on the raw ingredients and finished goods? Ingredient suppliers may provide incorrect information to manufacturers that can end up on the product label. What is the manufacturer doing to ensure quality and efficacy of the ingredients in their products? Are they doing their own testing or taking the word of their suppliers? High-quality supplements should include tests on raw materials as well as final formulations. Supplement ingredients lose efficacy over time. Ask whether products are tested at expiration date, and not just at time of manufacture.

Bariatric surgery dietary supplements tested for quality

Label accuracy and transparency: Ask whether the sources have been chosen with a bariatric patient’s physiology in mind. Some mineral sources can cause GI distress or be less bioavailable. Read the supplement facts label. Are the vitamin sources listed? As an example, vitamin D3 is preferred over vitamin D2 because it is more effective at maintaining blood levels of vitamin D.5 Are minerals in the amino acid chelate form which is easily absorbed or are they in forms such as sulphates, oxides of fumarates which are poorly absorbed and can cause unwanted gastrointestinal side effects?

Is the facility the supplements are manufactured in a TGA-facility and GMP-Certified: The Therapeutic Goods Administration (TGA) regulates the production of medicines in Australia and ensure manufacturers comply with strict guidelines to ensure the safety of people who consume these supplements. However as many powders are often considered to be foods, not medicines, they do not always have to produced according to pharmaceutical standards. Check that your supplements come from a TGA-approved, and Good Manufacturing Practice (GMP) – certified facility if you are looking for the best possible quality.

TIP 3: Choose a product that you like and are willing to take every day

Protein shakes for bariatric surgery patients

While we know that there are bariatric-specific, identified doses of vitamins and minerals that your body needs daily to avoid a nutrient deficiency, we also know that you must take your supplements in order for them to work.

If at first you don’t succeed, try and try again! Healthcare practitioners know that patients are much more likely to stick to their regimens lifelong when they enjoy taking their supplements. Experiment with flavor options of chewables, methods to mix your powders, or including protein powders in recipes to avoid getting tired of your supplements.

Remember, to avoid nutrient deficiencies after surgery, it is critical that you do the following lifelong:

  • Take vitamin and mineral and protein supplements (at specific doses) every day
  • Follow-up with your healthcare practitioner annually

The BariNutrics team of scientists and clinicians review literature and guidelines to ensure our products align with requirements. Our product development process includes testing on raw materials, formulations after blending, finished products, and products at expiration date to ensure efficacy. Explore BariNutrics multivitamins, calcium, and protein offerings today.


  1. Shankar P et al. Micronutrient deficiencies after bariatric surgery. 2010 Nov-Dec;26(11-12):1031—7.
  2. Patel JJ et al. Micronutrient Deficiencies After Bariatric Surgery: An Emphasis on Vitamins and Trace Minerals. Nutr Clin Pract.2017 Aug;32(4):471—480.
  3. Parrott J et al. American Society for Metabolic and Bariatric Surgery Integrated Health Nutritional Guidelines for the Surgical Weight Loss Patient 2016 Update: Micronutrients. Surg Obes Relat Dis, Volume 13 , Issue 5, 727—741.
  4. Aills L et al. ASMBS Allied Health Nutritional Guidelines for the Surgical Weight Loss Patient. Surg Obes Relat Dis.2008 Sep-Oct;4(5 Suppl):S73—108.
  5. Tripkovic L et al. Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis. Am J Clin Nutr.2012 Jun;95(6):1357—64