The Effects of Zinc and Selenium Co-Supplementation on Resting Metabolic Rate, Thyroid Function, Physical Fitness, and Functional Capacity in Overweight and Obese People under a Hypocaloric Diet: A Randomized, Double-Blind, and Placebo-Controlled Trial

Abstract

Evidence of the effectiveness of zinc (Zn) and selenium (Se) on resting metabolic rate (RMR) and physical function parameters in people with overweight and obesity is scarce, while the effects of zinc and selenium on thyroid function and body composition are still a topic of debate and controversy. The aim of this randomized, double-blind, and placebo-controlled trial was to examine the effects of a hypocaloric diet and Se–Zn co-supplementation on RMR, thyroid function, body composition, physical fitness, and functional capacity in overweight or obese individuals. Twenty-eight overweight–obese participants (mean BMI: 29.4 ± 4.7) were randomly allocated (1:1) to the supplementation group (n = 14, 31.1 ± 5.5 yrs, 9 females) and the placebo group (n = 14, 32.1 ± 4.8 yrs, 6 females). The participants received Zn (25 mg of zinc gluconate/day) and Se (200 mcg of L-selenomethionine/day) or placebo tablets containing starch for eight weeks. The participants of both groups followed a hypocaloric diet during the intervention. RMR, thyroid function, body composition, cardiorespiratory fitness (VO2max), and functional capacity (sit-to-stand tests, timed up-and-go test, and handgrip strength) were assessed before and after the intervention. A significant interaction was found between supplementation and time on RMR (p = 0.045), with the intervention group’s RMR increasing from 1923 ± 440 to 2364 ± 410 kcal/day. On the other hand, no interaction between supplementation and time on the thyroid function was found (p > 0.05). Regarding the effects of Zn/Se co-administration on Se levels, a significant interaction between supplementation and time on Se levels was detected (p = 0.004). Specifically, the intervention group’s Se serum levels were increased from 83.04 ± 13.59 to 119.40 ± 23.93 μg/L. However, Zn serum levels did not change over time (90.61 ± 23.23 to 89.58 ± 10.61 umol/L). Even though all body composition outcomes improved in the intervention group more than placebo at the second measurement, no supplement × time interaction was detected on body composition (p > 0.05). Cardiorespiratory fitness did not change over the intervention. Yet, a main effect of time was found for some functional capacity tests, with both groups improving similarly over the eight-week intervention period (p < 0.05). In contrast, a supplement x group interaction was found in the performance of the timed up-and-go test (TUG) (p = 0.010), with the supplementation group improving more. In conclusion, an eight-week intervention with Zn/Se co-supplementation combined with a hypocaloric diet increased the RMR, TUG performance, and Se levels in overweight and obese people. However, thyroid function, Zn levels, body composition, and the remaining outcomes of exercise performance remained unchanged.

The Importance of Micronutrient Adequacy in Obesity and the Potential of Microbiota Interventions to Support It

“…With weight loss, blood levels of vitamins A, E, C, and B1 were found to decrease [28][29][30], while no appreciable changes in Se and Ca were noted [33,35]. On the other hand, the status of Mg, Fe, and Zn, as well as vitamins B6, B9, and B12, was shown to improve [28,31,32,34,36].…”

Circulating and Tissues Concentrations of Selected Trace Elements in Response to Moderate Physical Exercise: Protective Effects of Cucurbita pepo Seeds Oil Extraction

“…However, the dynamics and biochemical processing of these elements vary; selenium (Se) is highly absorbed, unlike Mn. Se and Zn are primarily excreted through urine, whereas Mn is mainly eliminated through feces (3,4).…”

Moderate selenium mitigates hand grip strength impairment associated with elevated blood cadmium and lead levels in middle-aged and elderly individuals: insights from NHANES 2011–2014

“…This underscores a dose-response relationship concerning Se's health effects. Furthermore, a study highlighted that combined supplementation of zinc (Zn) and Se could boost physical functionality in overweight individuals undergoing calorie-restricted diets, hinting at Se's potential benefits in enhancing physical performance (Zavros et al, 2023).…”