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  • Writer's pictureDra. Andrea Pereira

Vitamin D, Calcium, and Zinc Deficiency after Bariatric Surgery

Vitamin D and Calcium

Vitamin D is a regulator of calcium metabolism. Its deficiency can reach 73% in post-surgical patients, being more related to osteoporosis, secondary parathyroid disease, and calcium disorders. The leading cause is malabsorption due to surgical reduction of the gastrointestinal tract. Still, reduced consumption of foods rich in calcium and vitamin D due to intolerance can exacerbate the condition and increase the risk of fractures.

As bone loss and osteoporosis do not present symptoms, we should routinely perform bone densitometry examination to make the diagnosis. We must add parathyroid hormone, total calcium, phosphorus, 25-OH vitamin D, and 24-hour urine calcium levels in these cases.

Some cases of depression are associated with vitamin D deficiency, but most patients experience no symptoms at all.

Prophylactic oral replacement of calcium citrate and vitamin D (cholecalciferol or ergocalciferol) is indicated to minimize parathyroid problems without inducing urinary calcium loss in patients undergoing this type of surgery.

In the case of deficiency, we must also adjust the consumption of calcium and vitamin D in the oral diet. Depending on the degree, we start supplementation in the form of tablets.

The indication of sunbathing to improve the absorption of vitamin D should always be associated with the use of sunscreen so as not to increase the risk of skin cancer. Remembering that the elderly have a reduced ability to convert vitamin D. Hence, it is often useless to increase sun exposure in this group of patients, so we do oral replacement of converted vitamin D.

We emphasize that the consumption of foods with calcium in Brazil has decreased due to the fad of lactose intolerance. Many people who consumed milk and dairy products stopped because they thought they had this intolerance. This should be discussed and evaluated by an appropriate professional, avoiding the risk of osteoporosis by reducing unnecessary dietary calcium consumption.


Zinc is a trace element that comprises more than 300 metalloenzymes in structural components, hormones, immune system, and nucleic acids, and obese people tend to have lower serum levels of this element.

The absorption of fats is associated with zinc, which is also impaired after surgery. Most patients with this deficiency, which can occur in 50% of them, are asymptomatic, but some symptoms may be present, with hair loss being the most frequent.

In cases of early deficiency, we can have the clinical picture of acne, reduction or lack of taste, deficiency of the immune system with an increase in infectious conditions, infertility, and, in the case of adolescents, delay in growth and sexual maturation. In advanced cases, the most common symptoms are hair loss, skin lesions, diarrhea, lack of appetite, night blindness, recurrent infections, and delayed healing of skin lesions.

The treatment of zinc deficiency, in addition to diet adequacy, is the use of zinc tablets. We must be careful because excessive zinc supplementation can lead to copper deficiency (described elsewhere)

Don't wait to have these symptoms to seek help. See your doctor and get tested annually after bariatric surgery. Follow-up is critical before and after surgery to prevent nutritional deficiencies and weight gain.

Dr. Andrea Pereira, MD, PhD


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