## 5 Effects of Micronutrient Supplementation on Weight Management and Metabolic Health in Obesity
### Effects of Micronutrient Supplementation on Lipid Homeostasis  
The effects of micronutrient supplementation on selected indicators of lipid homeostasis are summarized in Table 4. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Micronutrient** & **Studied Group** & **Number of People** & **Measure** & **95\% Confidence** \\  & **Included** & & **Interval** & **Reference** \\ \hline Cr & Adults with T2D & 636 & WMD \(-0.3\) & \(-0.7\), \(0.2\) & [58] \\ \hline \hline \end{tabular} MD—mean difference, SMD—standardized mean difference, WMD—weighted mean difference, DBM—difference between median weight loss for treatment and control group, T2D—type 2 diabetes, OW—overweight, OBM—obesity, MetS—metabolic syndrome, T2D—type 2 diabetes, NAFLD—non-alcoholic fatty liver disease, PCOS—polycystic ovary syndrome, * statistically significant difference reported in the study. In grey, data from RCTs were highlighted; remaining data were sourced out from meta-analyses; * denotes patients eligible to participate in the study carried out in this country.  
\end{table} 
Table 3: _Cont._Meta-analyses reported significant beneficial effects of supplementing Zn, Se, Ca, and vitamins C, B1, and B9 on at least one of the outcomes reported in Table 4, with Zn giving the greatest effect size for triglycerides (TG; WMD = \(-17.4\) mg/dL), total cholesterol (TC; WMD = \(-19.6\) mg/dL), low-density lipoprotein (LDL; WMD = \(-8.8\) mg/dL), and high-density lipoprotein (HDL; WMD = \(4.8\) mg/dL) among studied micronutrients [88; 90; 92; 94; 95]. An exceptionally high TG decrease was also reported for supplementation with vitamin B1 (WMD = \(-20.4\) mg/dL) but, due to wide confidence intervals, this finding was not statistically significant [91]. Mentioned effect sizes might be of clinical importance for mild cases of dyslipidemia since they allow for the modification of levels considered to be elevated by about 10% (the reference levels are \(\geq\)150 mg/dL for TG; \(\geq\)190 mg/dL for TC; \(\geq\)100 mg/dL for LDL; and for HDL < 40 for men and <50 mg/dL for women [96]). One of the important properties of micronutrients that could partly explain their beneficial influence on lipid homeostasis is the ability to scavenge free radicals. The antioxidative properties of vitamin C, Se, and Zn may improve the resistance of the adipose tissue to inflammation [97; 98; 99]. Furthermore, since vitamin C plays a role in the conversion of cholesterol to bile acids, the adequacy of its concentration may regulate blood cholesterol levels, especially LDL fraction [90]. On the other hand, animal research has shown that Zn supplementation exhibits hepatotoxicity effects and increases fat excretion with feces [100]. Other minerals, such as Ca and Mg, are known to form soaps with fatty acids and bile in the digestive tract and in this way prevent a part of this macronutrient from entering the bloodstream [80; 101]. This mechanism may explain the decrease of the accumulation of adipose tissue in animals on an obesogenic diet when supplemented with Ca [102], but in addition, the suppression of parathyroid hormone and 1, 25-dihydroxy vitamin D3 expression associated with a greater intake of Ca may contribute to the effect [103]. The supplementation of diet with vitamins B9 and B12 is known to decrease the concentration of homocysteine [104]--an amino acid that when present in excess may lead to dysregulation of lipid homeostasis and fat accumulation in tissues [105]. Unlike for vitamin B9, the number of studies on the efficacy of vitamin B12 supplementation in supporting the homeostasis of lipids in humans is very scarce. The available works did not show significant beneficial effects on lipid profile in T2D and non-alcoholic fatty liver disease (NAFLD) patients [79; 106], but clearly more research on the topic is required. Vitamin B1 is a cofactor for enzymes catalyzing the metabolism of not only lipids but also glucose and amino acids [107].