Iron nutriture following roux-en-y gastric bypass surgery

Breanne N Wright, Purdue University


Roux-en-Y gastric bypass surgery (RYGB) is effective for weight loss, but is commonly associated with iron deficiency and its clinical manifestation, anemia. Diagnosing iron deficiency is complex because iron status depends on other nutrients; additionally, anemia following surgery is not specifically due to deficiency in iron, as it can be due to deficiencies in other nutrients including zinc, copper, vitamin B6, folate, and vitamin B 12. In patients who have undergone RYGB, our aims were to 1) conduct a comprehensive assessment of nutrients involved in iron homeostasis, 2) determine the contribution of dietary intake to iron deficiency, and 3) describe associations between anemia and nutritional status of iron and other nutrients. Systemic measures of hemoglobin, ferritin, serum transferrin receptor (sTfR), total iron binding capacity (TIBC), copper (Cu), vitamins B6 and B 12, folate, zinc (Zn), and C–reactive protein (CRP) were determined using reference methods. Iron deficiency equaled having ≥ 2 abnormalities in: ferritin, sTfR, sTfR:ferritin, or TIBC. Ferritin, a measure of iron stores, was defined as normal (ferritin ≥ 20 mcg/L) or low (ferritin < 20 mcg/L). Statistics included prevalence, mean ± standard error of the mean (s.e.m.) for normally–distributed data, median ± semi-interquartile range for skewed data (indicated with an asterisk [*]), frequency tables, t–tests (independent, by group), correlations, and general linear models (significant if p < 0.05). Subjects (N=70) were 91% female, age 49 ± 1 years, *4 ± 2 years post surgery, and 79% Caucasian. Fifty–six percent of the total population and 96% of the subpopulation with anemia (N=26) presented with deficiencies related to iron nutriture, including deficiencies in iron, zinc, copper, vitamin B6, folate, and vitamin B12. The most prevalent nutrient deficiencies in the total population and the subpopulation with anemia were iron and zinc; prevalence of iron and zinc deficiency in the total population was 24.3% and 20.0%, respectively, and prevalence of iron and zinc deficiency in the subpopulation with anemia was 46.2% and 23.1%, respectively. Participants in the total population and the subpopulation with anemia were also deficient in copper, vitamin B6, vitamin B 12, and folate (11.5% and 26.9%, respectively). In the total population, iron and zinc deficiency occurred in isolation and also in combination with other nutrient deficiencies; all other nutrient deficiencies occurred in combination. In the subpopulation with anemia, only iron deficiency occurred in isolation. The dietary intake of the study population exceeded the RDAs for all nutrients assessed. In addition, patients with low ferritin concentrations consumed lower total energy (p= 0.009), fat (p= 0.026), protein (p=0.013), and animal protein (p=0.023), compared to patients with normal ferritin concentrations. Dietary intake of heme iron was correlated with years post–RYGB surgery (r=0.67, p<0.05). In conclusion, in a community-based surveillance of RYGB patients we found that, more often than not, RYGB patients presented with micronutrient deficiencies related to iron nutriture; this includes deficiencies in iron, copper, zinc, vitamin B6, folate, and vitamin B12 . It was more likely for multiple deficiencies to occur simultaneously than for deficiencies to occur alone. In addition, there was a high prevalence of anemia, a clinical manifestation of deficiencies in these nutrients. Implications of these findings are that clinicians who evaluate post–RYGB patients, especially patients who present with known symptoms or manifestations of iron deficiency, should also screen patients for deficiencies in copper, zinc, vitamin B6, folate, and vitamin B12, as these deficiencies are also prevalent following surgery, may occur simultaneously with iron deficiency, and are also implicated in anemia. Based on our findings that RYGB patients who have more favorable iron stores consume more energy, fat, and protein than patients with low iron stores, increasing protein intake following surgery may improve iron status; although, increasing consumption of fat may have detrimental effects on weight regain in the RYGB population. Findings of this study may be used to enhance prophylactic measures and treatments for iron deficiency following RYGB.




Gletsu-Miller, Purdue University.

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