INTRODUCTION:

Obesity is a physical manifestation that affect the health as well as quality of life of individuals. Many individuals consume substantially unhealthy amounts of food, which is a primary reason for obesity. It is multifaceted disease where the surplus of body fat is linked to environmental factors and genetic predisposition. Grievous illnesses as well as psychological and physical ailments are often seen in patients with serious obesity. Obesity noticeably abate life expectancy, principally among the adolescent population^[1]. Worldwide about 2.5 million deaths occurring annually can be assigned to obesity. Programmes that incorporate competent physical activity, behavioral alteration, psychological backing and the use of medications are the first choice of care for severe obesity.

Anyhow, in countless cases of severe obesity, non-surgical treatments neglects in providing continuous or sustained weight loss wherein surgical therapy can be suggested in particular cases. Bariatric surgery is extensively executed to induce weight loss and is recommended for individuals who have a BMI>40 or BMI>35kg/m²with co-morbidities. A noticeable weight loss, an enhancement in various obesity related medical condition are connected by this treatment. The different categories of bariatric methods include gastric banding (GB), biliopancreatic diversion, duodenal switch, Rous-en-Y gastric bypass (RYGB), gastrectomy and isolated intestinal bypass^[2]. The surgeries range from completely restricting (restrictive like the gastric band) the consumption ability of the GI tract to purely malabsorptive (jejuno-ileal bypass) to an intermediate condition of a hybrid of intake restriction and decreasing the absorptive capacity of the intestines (restrictive/malabsorptive RYGBP). The RYGB is a classical restrictive/malabsorptive surgery. The gastric capacity is decreased by 90- 95% in this procedure. Inspite of multiple clinical benefits, a distinguished complication of the surgical therapies for obesity is micronutrient and malnutrition in adequacy due to reduced intake or malabsorption that are most frequently seen after malabsorptive or mixed surgical procedures rather than restrictive procedures. Other factors for nutritional deficit include post surgery food intolerance, pre operative deficiencies, taste changes and eating habits and decreased compliance to dietary modification^[3]. The deficiencies of essential nutrient can predispose a patient to life threatening complications like anemia, osteoporosis, neurological disorders and malnutrition. The focus of this article is to review nutritional deficiencies after bariatric surgery in adult and adolescent population and to summarize current recommendations for screening and supplementation.

Nutritional deficiencies:

Micronutrient deficiencies

These are the common extensive adverse events following bariatric surgery which can steer to broad ranging symptoms, very commonly anemia and neurological dysfunction. Deficiency of iron, vitamin B12, folate, calcium, vitamin D are mostly observed after RYGB surgery^[4]. Assessing the accurate risk of developing micronutrient deficiencies is daring as there has been no concord on the proper amount and type of mineral and vitamin supplementation after bariatric surgery treatments. Deficiency of iron and anemia are the mostly found nutritional complication after bariatric surgery. Patients having mild anemia are likely to be asymptomatic whereas as it worsens they can develop symptoms like fatigue, pallor and dyspnoea on exertion. Those who have underwent restrictive as well as surgical procedures that are malsbsorptive are at high risk of developing deficiency of iron^[5]. According to Brolin RE et al, iron deficiency occurred in 49-52% in super obese patients acceded to RYB. Pregnant and menstruating females are vulnerable to develop iron deficiency. The prevalence of iron deficiency or anemia predicted by the American Society of Bariatric Surgery is about 14 – 16% in RYGB and 21 – 26% after biliopancreatic diversion^[6]. Since there is decrease in HCL production after restrictive surgery, there will be a decline in gastrointestinal tract capacity and iron is less available to be absorbed. For iron absorption, dietary iron (ferric iron) must be reduced to ferrous state by the acid production of the stomach. Multivitamin tablets alone cannot alleviate the bodily iron needs^[7]. So additional iron supplements are needed to correct it (300mg off ferrous sulfate 3 times a day associated with ascorbic acid). An incidence of 39% and 13.1% at 4 years after RYGBP was reported bySkroubis et al and Kalfarentzos et al. Assessment of serum ferritin and hemoglobin is the best diagnostic test for detecting iron deficiency A combination of iron supplements and vitamin c was seen to be more effective in decreasing iron deficiency as suggested by some reports^[8].

Vitamin B12 are mostly important for various hematological and neurological activities. The absorption of Vitamin B12 takesplace in the terminal ileum, assisted by an intrinsic factor produced from the antrum of stomach. Body stores about 2000 microgram of vitamin B12, where the average daily requirement is about 2microgram. Since the body has enough stores of it, Vitamin B12 deficiency is predominantly seen after 1-9 years of bariatric surgery. The patient develops symptoms of vitamin b12 deficiency only when the body stores are depleted below 5%. clinical manifestations include tingling, numbness, coordination disturbances and memory disturbances.

Deficiency of folic acid is uncommon as it is absorbed throughout the small intestine. Deficiency of folic acid can contribute to macrocytic anemia, priastrinopenia, decreased leucocytes or inflammation of tongue. It can lead to growth retardation and congenital defects. Folate deficiency can be exacerbated by vitamin b12 deficiency as the latter helps in the conversion of folate to its active compound. Cooper et al observed that at 1year folate and vitamin b12 deficiencies are not seen in patients, though the mean serum concentration of folic acid declined considerably at twelve months follow up^[9]. Brolin et al suggested the incidence of vitamin B12 deficiency to 12-33% for those who underwent RYGBP and lower incidence of vitamin B12 deficiency who underwent a distal RYGBP. Skrubis et al reported the occurrence as 22% for those who underwent BPD at 4 years follow up. Daily oral vitamin B12 (350-600microgram/day) is effective in correcting vitamin B12 deficiency^[10].

Thiamine is absorbed throughout duodenum more preferentially in acidic pH at the proximal portion. The etiology of thiamine deficiency is due to decreased HCl production. Thiamine is mostly stored in skeletal muscles, brain, heart, liver, kidney and body stores about 25-30mg of thiamine which can be depleted in 2-3 weeks during a dietary deficient state^[11]. The most common neurological and psychiatric exhibition of thiamine deficiency is Wernicke’s encephalopathy. Thiamine deficiency can also cause nausea, constipation. Thiamine is important for the carbohydrate metabolism and the oral or parentral administration of carbohydrate is an accelerating factor for thiamine deficiency. About 50-100mg/day IV or IM can be given during the onset of symptoms can lead to some resolution of complication^[12].

Vitamin D and Calcium deficiencies are the primary causes for bone loss post surgery. The decrease in serum calcium is caused due to reduced absorption, since the main sites for its absorption namely duodenum and proximal jejunum is bypassed^[13]. Deficiency of calcium can be worsened by its low intake due to poor tolerance to dairy products. Daily calcium supplements such as calcium citrate from 1200 to 2000mg/day is suggested.

Bariatric surgery affects the vitamin D status resulting in hypovitaminosis D as a result of poor fat absorption, due to the bypass of the main absorption sites for lipid soluble vitamins in the small intestine^[14]. Current guidelines recommend at least 5000IU/d to maintain adequate levels of vitamin d. recent studies suggest that vitamin D levels should be maintained at atleast 25-30ng/ml for the primary prevention of bone loss or fractures.

Although most literatures focus on calcium and iron deficiency, other minerals like magnesium, zinc, copper selenium have also found to be low in bariatric patients^[15]. These minerals have an important role to play in several biochemical pathways as cofactors and their paucity can result in neurological, cardiac and gastrointestinal problems.

Macronutrient deficiency:

Deficiency of protein is a very common macronutrient complication related to malabsorptive surgical procedure. It is a result of protein indigestion and malbsorption. The symptoms of protein malnutrition involve swelling, loss of hearing and decreased serum albumin levels <3.5g/dl^[16]. As per consensus guidelines, protein malnutrition can be prevented by an intake of 60-120g. Severe malnutrition can be treated with protein supplements which are rich in branched chain amino acids.

Fat soluble vitamin deficiency:

Vitamin A, K and E are fat soluble vitamins. Fat malabsorption is common after RYGB and BPD as only 32%of dietary fat is absorbed^[17]. This is primarily due to short common pathways that lead to slower blending of fat with pancreatic enzymes and bile salts resulting in alteration in absorption of fat soluble vitamins.

In the presence of multivitamins, vitamin E deficiency is uncommon following bariatric surgery. Slater et al reported the incidence of vitamin E deficiency as 4% by the end of 4^th year following surgery. Dolan et al reported similar findings (5%) by the end of 2^nd year after BPD^[18].

Vitamin A deficiency is caused by decline in absorption of fat from the gut that is caused by malabsorptive procedures. Symptoms of vitamin A deficiency include nyctalopia that has been reported in a new born infant resulting from maternal malabsorption after BPD^[19]. The incidence of vitamin A deficiency reported in a study was found to be 69%.

There are limited number of studies on vitamin k deficiencies after bariatric surgery. In one study conducted by slater et al, vitamin K deficieny was found to be 68%^[20].

Zinc deficiency:

Fats help in the absorption of zinc. Decreased serum concentrations of zinc has been noted in patients after BPD or duodenal switch^[21]. It is also caused after gastroplasty due to reduced dietary intake. In patients having undergone vertical gastroplasty, resolution of hairloss after supplementing with increased doses of zinc sulfate has been reported.

CONCLUSION:

Bariatric surgery encompasses modifications to the gastrointestinal anatomy and physiology resulting in decreased absorption of macro as well as micro nutrients. It is a long term clinical problem for the patients who underwent the surgery. Thus patient’s nutrition status needs to be monitored on a regular basis depending on the type of procedure they have opted. Nutritional assessment in candidates prior to surgery is also necessary due to the prevalence of nutritional deficit prior to surgery. For all weight loss surgery patients, postoperatively multivitamins and calcium with vitamin D is highly recommended^[22]. Nutritional surveillance is necessary in the management of bariatric patients as it helps to increase patient’s adherence to dietary supplements, prevents weight regain, help in identification of nutritional deficiency despite therapy and improves the overall quality of life of the patient.

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Received on 05.08.2019 Modified on 21.08.2019

Res. J. Pharmacology and Pharmacodynamics.2019; 11(3):120-123.

DOI: 10.5958/2321-5836.2019.00021.1