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Bariatric Multivitamins: Why They’re Vital After Surgery

Bariatric Multivitamins

Bariatric Multivitamins: Why They’re Vital After Surgery

Bariatric multivitamins are an important addition to your post-surgery diet, as your body’s ability to obtain and absorb adequate micronutrients will change after your operation.

In this blog, we explain their benefits and compare one generic multivitamin to a bariatric supplement.

But first, we’re going to discuss what micronutrients are and why they’re so vital for our body and its ability to function well.

What are Micronutrients?

Vitamins and minerals are micronutrients that are found in the foods we eat. They are either naturally occurring or can be added into foods and drinks.

Why are Micronutrients Important?

Micronutrients play an essential role in all areas of the body, including but not limited to:

  • Brain health
  • Immune function
  • Building strong bones and teeth
  • Producing energy
  • Producing new cells and repairing damaged tissues
  • Preventing birth defects during pregnancy
  • Protecting vision
  • Transporting oxygen throughout the body, and
  • Blood clotting.

It is possible to obtain adequate micronutrients from a healthy and varied diet. However, a large percentage of the Australian population are micronutrient deficient at some stage in their life. For example, 34% of women of childbearing age and nearly 5% of healthy males are iron deficient. 

Hence, oral supplementation is often used to correct micronutrient deficiencies.  It is important to note that a person’s micronutrient requirements may increase depending on their age, gender, genetics, the presence of certain diseases and/or surgery, including bariatric surgery and during pregnancy.

Bariatric Multivitamins: Why Supplementation is Important after Surgery

After bariatric surgery, your ability to obtain adequate micronutrients from the foods you eat is limited due to significantly smaller portion sizes. In addition, weight loss surgery alters the way your body breaks down and absorbs various nutrients because of changes made to your gastrointestinal tract.

Thus, it is vitally important you follow the nutrition advice provided by your Dietitian regarding which supplements you need to take after bariatric surgery. The recommendation will depend on age, the type of weight loss surgery, as well as pre-existing and post-surgery micronutrient deficiencies.

Vitamin Deficiency after Bariatric Surgery

The most common vitamin and mineral deficiencies seen after bariatric surgery includes iron, vitamin B12, folate, vitamin D, zinc, thiamine (vitamin B1) and calcium.

Long term nutrient deficiencies can lead to poor health and a lower quality of life, due to the onset of various symptoms, such as tiredness, mental fog, night blindness and weak and brittle bones.

Once a deficiency develops, it can take several months to correct with oral supplementation, and will require strict monitoring.

We recommend you get a blood test every 3 months in the first year, and then every 6-12 months to monitor for deficiencies.

Unless otherwise specified by your Dietitian, it is important to take a bariatric specific multivitamin after bariatric surgery.

Please contact one of our Dietitians if you are unsure about which supplement to take.

Table 1: Key Differences Between a Generic and Bariatric Specific Multivitamin

 Bariatric specific multivitamin:


BN multivitamin chewable

Taken x2/day*

Generic multivitamin:


Centrum multivitamins for adults

Taken x1/day*

Bariatric Guideline Range
Vitamins + Minerals   
Vitamin A (µg)750300800-1500
Vitamin B1 (Thiamine) (mg)122.12.7-12
Vitamin B2 (Riboflavin) (mg)103.21.1-2.2
Vitamin B6 (Pyridoxine) (mg)1.761.5-2
Vitamin B9 (Folic Acid) (µg)500400800-1000
Vitamin B12 (µg)50022350-1000
Vitamin C (mg)120**9045-90
Vitamin D3 (IU)100015800-3000
Calcium (mg)6004001200-2000
Copper (µg)0.750.52
Iron (mg)185Varies from 18-60
Manganese (mg)23.55-10
Selenium (µg)605560-120
Zinc (mg)157.58-28

*As per recommendation on the packaging

** Vitamin C is a water soluble vitamin. Risks associated with excess vitamin C consumption is minimal as vitamin C is often excreted in the urine. 

Inadequate amounts
High amounts

Table 1 shows that generic multivitamins can contain inadequate dosages of micronutrients required after bariatric surgery, and may thus lead to deficiencies long term.

Note: Our Dietitians can provide a few different options for bariatric specific supplements if you’re unable to take/source the BN multivitamins.

For any further questions about oral supplements, please contact us at or on (07) 3871 2277.

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