Baked Bread Enhances the Immune Response and the Catabolism in the Human Body in Comparison with Steamed Bread

Abstract

It is unclear whether different processing methods change the biological functions of foods and how these functions are evaluated in the human body. Here, steamed bread and baked bread, the traditional staple foods in China and many Western countries, were made by steaming and baking, respectively, using one piece of fermented wheat dough and then consumed by 16 healthy young volunteers. By detecting 38 cytokines, 12 metabolic enzymes, glucose, lactate, and nicotinamide adenine dinucleotide (NADH) in the serum, the cytokine network and central metabolic pathway network were investigated to compare the effects of the two staple foods on immunity and metabolism. Compared with steamed bread, baked bread increased (p < 0.05) concentrations of fractalkine and macrophage-derived chemokine, decreased (p < 0.05) the concentration of interleukin-1RA, increased (p < 0.05) the expression level of phosphofructokinase, and decreased (p < 0.05) the expression level of glucose-6-phosphate dehydrogenase in the serum. Two network analyses indicated that baked bread, as compared to the steamed bread, enhanced communication between immune cells, increased catabolism, and decreased anabolism. Further, a correlation analysis of cytokines and metabolic enzymes suggested that the two staple foods may affect metabolism by regulating the secretion of cytokines. These findings highlight how the same raw food material processed by different methods may have different impacts on immunity and metabolism in humans.

Keywords: Baked bread; Cytokine network; Human; Metabolic network; Steamed bread.

Figure 1

Central metabolic pathway metabolic network diagram containing the Embden–Meyerhof–Parnas (EMP) pathway, phosphopentose pathway (PPP), and tricaboxylic acid (TCA) cycle pathway. Ac-CoA, acetyl coenzyme A; G3P, glyceraldehyde-3-phosphate; G6P, glucose-6-phosphate; PYR, pyruvate; Ru5P, ribulose-5-phosphate.

Figure 2

Serum cytokine concentrations. Values are mean ± SEM. * p < 0.05.

Figure 3

The expression levels of 12 enzymes in the serum. Values are mean ± SEM. * p < 0.05.

Figure 4

Effects of steamed bread and baked bread on the cytokine network (a) and central metabolic pathway metabolic network (b). In the cytokine network, the thickness of the lines represents the strength of intercellular communication (the concentration change rate of cytokine i); the red line represents enhanced communication, and the blue line represents inhibited communication; the arrow represents the direction from secretory cell to the target cell. In the metabolic network, the thickness of the line represents the quantitative metabolic pathway flux; the arrow represents the direction of metabolic flux. The correlation analysis between the changed (versus control) cytokines and the metabolic enzymes were assessed by Pearson’s correlation test. The correlation is given by r value. The red line represents a significant (p < 0.05) positive correlation and the blue line represents a significant (p < 0.05) negative correlation.