Gastric Bypass Vitamins That Everyone Needs After Surgery

Gastric Bypass Vitamins That Everyone Needs After Surgery

Taking daily vitamins and supplements will be essential for the rest of your life following gastric bypass surgery. However, this may seem like a daunting task. Taking your vitamins becomes part of your routine. What can be challenging is figuring out what vitamins you need to take. People who have bariatric surgery are at risk for nutrient deficiencies, which can have severe health consequences. Therefore, knowing precisely what gastric bypass vitamins you need are an essential step in your recovery and weight loss journey. Here is your complete gastric bypass vitamin list to help you get started and stay on track.

Why Do I Need Vitamins to Post Gastric Bypass?

Before diving into the vitamins all gastric bypass patients will need, it is essential to understand why you need to take vitamins in the first place. Most weight-loss surgeries work by restricting the amount of food you can eat at one time. Consequently, this also limits the number of nutrients you can get daily. Thus, there is a severe risk for nutrients deficiencies, especially after major weight loss surgeries like gastric bypass.

Most weight-loss surgeries alter your digestive anatomy to make it harder to eat a large volume of food. Gastric bypass is one of these procedures. However, it has another mode of curbing your appetite and ability to consume larger quantities of food: it also changes your digestive hormones.

Gastric bypass, also known as Roux-en-Y, is a two-part surgical procedure. First, the surgeon cuts your stomach size down significantly to only eat a small amount of food at one time. Typically, the stomach is decreased to the size of a walnut. Second, the surgeon then re-routes the small intestine so a large portion is “bypassed” to reduce the number of nutrients you can absorb. By cutting down the stomach size and avoiding a large portion of the small intestine, digestive hormones are more likely to send signals that you are full sooner or not even hungry when meal times approach.

As you can imagine, these anatomical and hormonal changes can help people lose a significant amount of weight, but they also put you at greater risk for severe nutrient deficiencies.

It is important to understand why you need gastric bypass vitamins after surgery.

What Vitamins Do I Need After Gastric Bypass?

Vitamins are a significant part of your recovery and health maintenance after you undergo any bariatric surgery. Thus, many people wonder what vitamins to take after gastric bypass. The short answer is that everyone needs a personalized vitamin regimen after they have surgery. However, most people will need the same nutrients to support their bodies and ward off nutrient deficiencies that are all too common after weight loss surgery.


A multivitamin is a great way to get many essential nutrients in your system with just one pill. You can choose several multivitamins, some of which are even geared to bariatric surgery patients. When you are shopping for a multivitamin, make sure it is a complete vitamin, meaning it contains iron and other trace minerals that you usually get from your food. Your multivitamin should contain:

  • 200% of your Daily Value for most of the nutrients, especially iron, folic acid, and thiamin.
  • 100% of your Daily Value for zinc, copper, and other nutrients listed on the label.

When reading the label on the multivitamin you are considering, make sure that the following nutrients are available in these quantities:

  • Iron - 36 mg
  • Folic acid - 800 mcg
  • Thiamin - 3 mg
  • Zinc - 15 mg
  • Copper - 2 mg

Some bariatric multivitamins will also include vitamin D and B12, which are highly important for preventing deficiencies and health consequences. You may also find differences in iron concentrations in bariatric-specific vitamins. To find out what your individual iron needs are, consult your doctor and nutritionist.

A multivitamin can cut down on the number of supplements you need to take each day.

Calcium Citrate

You will need to supplement calcium in addition to your multivitamin. Calcium is a crucial mineral that plays a vital role in all of your body systems. Most notably, we know that it is one of the main components of bone and can help ward off bone disease like osteoporosis, which is prevalent in people who are overweight and obese.

Most gastric bypass patients will require between 1200-1500 mg/d of calcium daily. Calcium supplements generally contain less than this amount, so you will need to take these supplements a few times a day to meet your daily requirement. Keep in mind, calcium can interfere with some medications like thyroid medication, for example, so you will want to space out when you take this supplement from medications that may interact with calcium.

You will need more calcium than you can get through your post-gastric bypass diet.

Vitamin D

Like calcium, vitamin D is essential for your bones. However, it is also unique because it is one of the only essential nutrients we can make when our skin is in sunlight. Your ideal vitamin D dose depends on your blood levels of this nutrient. Likely, your doctor will monitor your vitamin D levels with blood work following surgery to see if you are at a therapeutic level. Sometimes, bariatric multivitamins include vitamin D. If so, make sure your multivitamin contains at least 3,000 IU of Vitamin D daily.

Vitamin B12

Vitamin B12 helps our bodies utilize energy, make new red blood cells, and keeps our nervous system healthy. People with B12 deficiencies often feel unwell and have low energy. To meet your daily needs of B12, you should aim to take 350-500 mcg daily or 1,000 mcg every other day. Sometimes, you can complete your daily requirements in a multivitamin that contains B12.

Usually, B12 supplements are available in chewable tablets or dissolve under the tongue (sublingual). You can also use a B12 nasal spray once weekly (500 mcg) or get a monthly injection of 1,000 mcg a month. The reason why nasal sprays and injections are at lower doses than you may expect is that your body can absorb these minerals more readily via these routes instead of through your stomach, where it is hard to absorb all that you need.


Nearly 45% of bariatric surgery patients are deficient in iron. This crucial mineral is essential in making hemoglobin and getting more oxygen and nutrients to your cells. Although iron is often in bariatric multivitamins, you may need to supplement more iron if:    

  • You are still menstruating or,
  • You have iron deficiency anemia

Most gastric bypass patients will require 36 mg daily. However, if you fall in either of the above categories, you may need to take 45-60 mg daily. People who are anemic will likely have unique iron requirements, which their doctor should determine.


Nearly 56% of bariatric surgery patients are deficient in folate. Also referred to as folic acid, folate is an important B vitamin that helps with DNA synthesis and repair and cellular division. Most multivitamins will contain folate, so it is important to make sure the one you select has at least 800 mcg in your daily dose.

Things to Consider With Your Gastric Bypass Vitamins

  • Avoid gummy vitamins as they tend not to contain all of the vitamins and minerals you need. Your best route is to go with a pill-based supplement or possibly an oral suspension or nasal spray, depending on the nutrient you are supplementing.
  • Liquid vitamins are gastric bypass may be gentler on your stomach and may increase your absorption rate. Similarly, chewable vitamins for gastric bypass patients may also be easier to digest.
  • Taking prenatal vitamins after gastric bypass is especially important if you wish to get pregnant. Because folate deficiencies are common in gastric bypass patients, women need to be extra careful in getting the right amount of folate, as folate deficiencies can lead to severe cognitive disabilities in babies.
Gummy vitamins may be more enjoyable to take, but they often lack in nutrients.

Research shows that the number of people with nutrients deficiencies after gastric bypass surgery is on the rise. To make sure you are not adding to this statistic, you must take your recommended vitamins after gastric bypass. Furthermore, studies show that gastric bypass patients are already nutrient-deficient even before surgery. Therefore, you must be diligent in making sure you are taking all of your vitamins after gastric bypass, as your risk for deficiency only increases.  

Ready to make your personalized gastric bypass vitamin list? Meet with your doctor and nutritionist to ensure you are on the right track to staying healthy and meeting your health goals.

Julia Rae Walker, RN, BSN, BA


Julia is an experienced critical care nurse with a background in pediatric and adult patient populations. Her passion is helping patients maximize their quality of life.

Gintas Antanavicius, MD, FACS, FASMBS


Dr. G is a co-founder of BariBuilder. A US-based expert surgeon with over 10 years of bariatric experience, he regularly publishes research in medical journals like SOARD, Obesity Surgery, etc.