By Sandy Wiita, MD and Charles Svendsen, MD

Patients undergoing Roux-en-Y gastric bypass or other malabsorptive procedures are educated preoperatively about the need to take vitamins and minerals for the rest of their lives. Many patients promise to be vigilant in exchange for a chance at successful weight loss. But what happens after surgery?

Bariatric teams and patients must monitor some of the following vitamins and minerals through regular blood tests based on your bariatric procedure. Even when patients consistently achieve normal results, it is important to continue testing, as levels can be depleted over time. 

Vitamin B1 (thiamin) is important for metabolism and normal brain and nerve function. Most patients can meet their Vitamin B1 needs with a multivitamin. Thiamin deficiency causes fatigue, poor memory, confusion, tingling toes and leg cramps. Frequent vomiting and excessive alcohol use increases the risk of deficiency.

Vitamin B6 is important for immune function, maintaining stable blood sugar levels, healthy skin and converting certain amino acids to serotonin, which helps prevent depression. Vitamin B6 deficiency can cause a sore or swollen tongue, cracks at the corners of the mouth, poor infection fighting ability, damage to nerves, confusion and excessive sleepiness or fatigue. Most patients can meet their Vitamin B6 needs with a multivitamin.

Vitamin B12 is important for nerve and brain cell health and the ability to produce new red blood cells. It is most effective when taken under the tongue, via nasal spray or by injection instead of swallowing pills. B12 is usually absorbed in the lower part of the stomach or the upper section of the small intestine (which are bypassed during gastric bypass surgery). A long term deficiency can cause irreversible nerve damage.

Vitamin D is necessary for optimal calcium absorption. Without it, the body has difficulty forming new bone tissue as it replaces broken down tissue, resulting in osteomalacia. Severe deficiencies can develop over time, causing bowing of the legs and shortening of vertebrae. Height loss can result because bones are not strong enough to support the body’s weight. Vitamin D3 is the most effective form of Vitamin D. Some researchers also believe Vitamin D may help prevent colon cancer and other types of cancer.

Calcium is Vitamin D’s partner in forming healthy bones. Blood clotting and muscle contraction, including the heart, are other important functions. Calcium citrate is more easily absorbed than calcium carbonate, due to low acidity in the stomach after gastric bypass surgery as well as age. Calcium is most efficiently absorbed when taken with a meal. It should not be taken with iron, as the two minerals compete for absorption.

Iron deficiency results in formation of small red blood cells that are unable to properly carry oxygen. This leads to weakness or fatigue. Iron deficiencies cause some people to crave ice or experience restless leg symptoms. Iron should be taken with Vitamin C to improve absorption. Men and postmenopausal women can often get enough iron in a multivitamin; premenopausal women may need a separate supplement.