Inadequate zinc intake in patients on dialysis linked to four-times greater mortality risk
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In a cohort of patients receiving in-center hemodialysis, researchers observed a high prevalence zinc intake below recommended values, which they found led to an increased risk for mortality in 12 months of follow-up.
Findings also indicated that patients who consumed less zinc had lower lean tissue index and lower intakes of protein and energy, highlighting the relationship between zinc and both nutritional and body composition parameters, Cristina Garagarza, MSc, of the nutrition department at Nephrocare and Universidade de Lisboa in Portugal, and colleagues suggested.
“The recommended dietary allowance of zinc for the general population is 8 mg/day for women and 11 mg/day for men, whereas the European Best Practice Guideline on Nutrition and Chronic Kidney Disease recommends a daily intake between 8 [mg] and 12 mg for women and 10 [mg] and 15 mg for men,” Garagarza and colleagues wrote. “The recent KDOQI clinical practice guideline on nutrition in chronic kidney disease suggests not to routinely supplement zinc in [hemodialysis] HD patients since there is little evidence that it improves nutritional, inflammatory, or micronutrient status ...
Considering an adequate zinc intake of key importance, and simultaneously considering the lack of studies evaluating the relationship between its consumption and survival in HD patients, the aim of this study is to analyze the relationship between zinc intake and mortality in HD patients.”
For the study, researchers included 582 patients from 37 dialysis centers. Researchers considered clinical and body composition parameters at baseline (the cohort had a median dialysis vintage of 65 months and 31.6% also had diabetes). Researchers also determined dietary intake (obtained using the food frequency questionnaire) and collected data on physical activity.
Of the total study population, 53.6% had a deficient zinc intake, with the mean intake being 9.6 mg per day (intake ranged from 2.1 mg per day to 42.7 mg per day). Looking at intake by gender, researchers found 51.2% of women had a low intake (mean intake was 8.3 mg per day) compared with 55.3% of men (mean intake was 10.4 mg per day).
Results showed patients with the highest zinc intake also had higher lean tissue index (12.9 kg/m2 vs. 12.5 kg/m2) and higher intakes of energy (2,984 Kcal per day vs. 1,561 Kcal per day) and protein (17.6% of daily energy intake vs. 15.7% of DET).
Zinc intake, mortality
During the 12-month follow-up, 29 deaths occurred leading to an overall mortality rate of 5%. Findings indicated patients with low intake were more likely to die than those who consumed the recommended values or above (7.4% with low intake died compared with 2.1% and 2.6%, respectively).
While researchers did not observe a higher hospitalization risk for patients with lower zinc intakes, results of a Cox regression analysis demonstrated patients who had zinc intake below recommended values had a 4.1 times higher risk for mortality. This finding was observed even after adjustments were made for age, diabetes, gender, dialysis vintage, albumin, lean tissue index, energy intake/kilogram of body weight and level of physical activity, Garagarza and colleagues noted.
Treatment, future research recommendations
“In HD patients, a zinc supplementation of 50 mg zinc per day for 3 [to] 6 months should be considered when existing chronic inadequate protein/energy intake and symptoms evoking zinc deficiency (impaired taste or smell, skin fragility, impotence, peripheral neuropathy). However, routine zinc supplementation is not recommend[ed] since the evidence that it improves nutritional, inflammatory or micronutrient status is considered to be insufficient,” the researchers concluded on the findings. “Finally, as there are some drugs frequently prescribed to HD patients which may promote zinc deficiency, such as calcium-based phosphate binders and oral iron supplements, we consider that medications prescribed should be taken into account when assessing nutritional status and adjusting zinc dietary intake in patients undergoing HD treatment.”
Garagarza and colleagues recommend assessing dietary zinc intake at a population level, suggesting that this will “provide information about the dietary patterns that may be associated with zinc adequacy or inadequacy and can help to identify populations or subpopulations at elevated risk for inadequate zinc intakes.”
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