A Review of Red Yeast Rice, a Traditional Fermented Food in Japan and East Asia: Its Characteristic Ingredients and Application in the Maintenance and Improvement of Health in Lipid Metabolism and the Circulatory System

Abstract

Red yeast rice has been used to produce alcoholic beverages and various fermented foods in China and Korea since ancient times; it has also been used to produce tofuyo (Okinawan-style fermented tofu) in Japan since the 18th century. Recently, monacolin K (lovastatin) which has cholesterol-lowering effects, was found in some strains of Monascus fungi. Since statins have been used world-wide as a cholesterol-lowering agent, processed foods containing natural statins are drawing attention as materials for primary prevention of life-style related diseases. In recent years, large-scale commercial production of red yeast rice using traditional solid-state fermentation has become possible, and various useful materials, including a variety of monascus pigments (polyketides) that spread as natural pigments, in addition to statins, are produced in the fermentation process. Red yeast rice has a lot of potential as a medicinal food. In this paper, we describe the history of red yeast rice as food, especially in Japan and East Asia, its production methods, use, and the ingredients with pharmacological activity. We then review evidence of the beneficial effects of red yeast rice in improving lipid metabolism and the circulatory system and its safety as a functional food.

Keywords: LDL-cholesterol; Monascus fungi; cardiovascular system; lipid metabolism; monacolin; pigment; polyketide; red yeast rice; solid-state fermentation; statin.

Figure 1

Appearance of red yeast rice.

Figure 2

Production method of red yeast rice described in “Tiangong Kaiwu”. Rice inoculated with Monascus fungi is divided between several bamboo trays, which are placed on shelves to maintain good air circulation. Ambient air during the culture is a key factor. The room in which the shelves are placed must be wide and there must be a high ceiling. The room must also be facing south to avoid afternoon sunlight and its temperature should be controlled. Rice inoculated with the fungi should be mixed up and down 3 times every 2 h.

Figure 3

Solid-state/liquid-state culture method of red yeast rice.

Figure 4

Tofuyo, a food that has been passed down the generations in Okinawa, Japan.

Figure 5

Major pigments (polyketides or azaphilone pigments) produced by Monascus fungi.

Figure 6

Monacolins (polyketides) produced by Monascus fungi.

Figure 7

Lactone and acid forms of monacolin K.

Figure 8

Time course change in appearance of red koji, which reddens during fermentation.

Figure 9

Time course change in the content of lactone form and acid form of monacolin K in red yeast rice during fermentation, quantified using the method specified by the Korea Food and Drug Administration (KFDA) [29].

Figure 10

Time course change in the contents of 3 azaphilone pigments in red yeast rice during fermentation, quantified according to the reference method [30].

Figure 11

Time course change in the contents of 2 amino acids (GABA and monascumic acid) in red yeast rice during fermentation, quantified by liquid chromatography-mass spectrometry (LC-MS) [16,17].

Figure 12

Biosynthetic pathway of cholesterol synthesis and the action of red yeast rice in it.

Figure 13

Effect of intake of red yeast rice produced by solid-state fermentation in normal healthy volunteers whose plasma cholesterol levels were 120 mg/dL or higher. Each bar indicates the mean ± standard deviation. *: Significant difference from start of ingestion (p < 0.05, paired ANOVA). #: Significantly different from the placebo group (p < 0.05, multiple comparison using Bonferroni).

Figure 14

Plasma concentrations of lactone form and acid form of monacolin K after single administration of purified monacolin K or red yeast rice (40 mg/kg monacolin K or dose of red yeast rice equivalent to 40 mg/kg monacolin K) in male SD rats (7 weeks old). Each bar indicates the mean ± standard deviation, quantified according to the reference method [43].

Figure 15

Difference in transmittance of plasma between red yeast rice-treated (2 weeks) and non-treated groups of male Japanese white rabbits (10–12 weeks old) fed a high-cholesterol diet. A decrease in turbidity in the red yeast rice-treated group is apparent. Each bar indicates the mean ± standard deviation. Significant differences were tested by Student’s t-test. Plasma cloudiness was evaluated by measuring the transmittance at a wavelength of 660 nm using an absorptiometer.

Figure 16

Time course changes in plasma viscosity in a control group and a red yeast rice-treated group in hypercholesterolemic model rabbits. Each bar indicates the mean ± standard deviation. Significant differences between control group and red yeast group were tested by Student’s t-test (#: p < 0.05, ##: p < 0.01). Plasma viscosity was measured using a plate and cone viscometer according to the reference method [50].

Figure 17

Time course change in contents of cholesterol in plasma low-density lipoproteins (chylomicron-cholesterol and VLDL-cholesterol) obtained from a red yeast rice-treated and control groups of hypercholesteremic model rabbits. Each bar indicates the mean ± standard deviation. Significant differences between control group and red yeast group were tested by Student’s t-test (##: p < 0.01). Plasma lipoprotein cholesterol was quantified according to the reference method [51].

Figure 18

Expected effect on the circulatory system of red yeast rice and its components.