Taking vitamins should be an important part of everyone’s routine, but it’s especially important to those who have undergone bariatric surgery.

Bariatric surgery involves removing a section of the stomach in order to make it smaller so that you can’t eat as much food. Although the procedure will help you lose weight, it also limits the amount of nutrients you take in as part of your daily diet, which is why bariatric surgeon Dr. John Dockins, MD, FACS, FASMBS says he always stresses the importance of vitamins to his patients.

“Taking multivitamins every day is crucial to patients’ success before and after surgery. This is accomplished in two ways. First, if a patient has any deficiencies in essential vitamins and minerals, we can detect and optimize these levels before surgery. Secondly, the habit of taking multivitamins every day will prevent the development of any nutritional deficiencies after surgery. With this strategy, we can ensure that all patients will reap the wonderful health benefits of having optimal nutrition,” says Dr. Dockins.

Here’s a rundown of the vitamins Dr. Dockins recommends for weight loss surgery patients.

Multivitamin

This is the first vitamin you will take following bariatric surgery and Dr. Dockins often recommends taking it twice a day for the first six months.

Calcium

Although there is calcium in multivitamins, it may not be enough to make up for the calcium lost in your diet. You may need a calcium supplement that contains 1,000 mg to 1,500 mg of calcium each day. Because your body can only absorb 500 mg at a time, it’s best to take the vitamins at three points throughout the day.

Iron

Iron is necessary to build up healthy red blood cells, but it can cause stomach upset. Look for supplements that contain ferrous fumarate, ferrous sulfate or ferrous gluconate so that your body can better absorb it.

Vitamin D

You need Vitamin D to help you absorb calcium. It’s recommended you take at least a 1,000 IU vitamin supplement a day following bariatric surgery.

Vitamin B-12

Vitamin B-12 promotes both brain function and the building of healthy red blood cells. Because the portion of the stomach that aids in the absorption of this vitamin is removed during bariatric surgery, you need to either take a liquid supplement or a supplement that dissolves on your tongue. It’s recommended that you take 500 mg of B-12 a day.