Red yeast rice (紅麴) reduces the blood level of low-density lipoproteins (LDL, 低密度脂蛋白), or so called the BAD cholesterol (膽固醇), and long-term supplementation decreases the incidence of cardiovascular disease (心血管疾病). The mechanism of red-yeast-reducing-LDL is due to the structure of active ingredients(活性成分), the Monacolin K, similar to the Statins hyperlipidemia medicine(高血脂藥), so they may have similar benefits and side effects.
However, one of the dietitians in our company said, some health supplements(保健食品) are not only free from Monacolin K but share similar hypolipidemic(降血脂的) effects as Statins, but cause lower adverse reactions.
Was it true or was it not? Let’s take a look of what’s going on.
1. What are benefits and precautions of Red Yeast Rice?
Red Yeast Rice is the product of red yeast grown on white rice. The powdered yeast-rice mixture is a dietary staple (主食) in Asia and has been used in traditional Chinese medicine (中藥).
Red yeast is also available as an oral health supplement.
It might contain compounds (化合物) that appear to lower cholesterol levels. One of those compounds is called monacolin K, which has the same structure as the prescription (處方藥) cholesterol-lowering drug, lovastatin.
Except for Monacolin K, studies found that active ingredients like Monascin、Ankaflavin also have the potential to reduce cholesterol.
While these various red yeast health supplements have different active substances, they all carry similar potential side effects and precautions (注意事項).
Generally speaking, avoid using red yeast if you are pregnant, breastfeeding, drinking grapefruit juice, or having liver, kidney problems.
2. Characters of Medicine and Health Supplement
Red yeast rice contains chemicals same as Lovastatin.
Lovastatin may cause liver impairment (肝損傷) and muscle damage (肌肉損傷) when the cumulative dose is too high.
Some researchers indicate red yeast might also cause liver damage to the same degree as lovastatin. Also, studies raised the concern that red yeast products contain a contaminant (汙染物) called citrinin, which can cause kidney failure (腎衰竭).
Therefore, ask your doctor or pharmacist first before taking red yeast products if you have liver or kidney problems.
3. Will Red Yeast cause Muscle Pain?
Is it real that Monacolin K of red yeast health supplement causes muscle damage?
Actually, this statement is not that correct. Adverse reactions of any medicine are mostly decided by the cumulative dose (exposure) and cumulative time.
According to a long-term safety study, 744 patients received lovastatin for an average duration of 2.5 years, 40 mg twice daily (80mg/day).
The reported side effect of muscle disorders or myopathy (肌肉病變) is 0.5%, defined as the Rare Adverse Effects罕見副作用(less than 1%), and these discomfort symptoms are reversible (可逆的) when stop taking medicine.
Another lovastatin study in 8,000 patients also indicated similar result (EXCEL Study).
Moreover, based on Health Supplements Regulations in Taiwan, daily uptake of Monacolin K cannot be higher than 15mg/day, much lower than the dose used in previous clinical trials (80mg/day).
So the chance to cause muscle discomfort in Red Yeast Health Supplements basically can be regarded as hardly ever, or neglectable (可忽略的).
4. Potential Food-Drug Interactions of Red Yeast
When it comes to Food-Drug Interactions, we need to be aware of the character of grapefruit (葡萄柚) and the blood-clot-treating medicine Warfarin.
Simultaneous (同時的) use of the anticoagulant (抗凝血劑) Warfarin and red yeast will increase the concentration of Warfarin and raise the concern of bleeding. The reason is that Warfarins are mainly metabolized by the liver enzyme CYP450 (cytochrome P 450), and most of the red yeast supplement also goes through the same metabolism (代謝).
Competing for the same metabolic receptor makes some Warfarin unable to be metabolized and excreted, resulting in the increase of blood concentration (血液濃度).
Grapefruit and Pomelo (柚子) are often seen at the Chinese Moon Festival (中秋節). They may have the interaction (交互作用) with red yeast as well. Grapefruit inhibits the activity of CYP3A4. The concurrent uptake of red yeast with grapefruit may rise the red yeast concentration and cause potential side effects.
Therefore, avoid eating warfarin, grapefruit or pomelo while using red yeast products unless your health professional instructs you otherwise.
To conclude, the red yeast dietary supplement shows good safety under the authority's regulation. The chance to cause side effects in the corresponding product basically can be regarded as hardly ever, or neglectable. Concurrent uptake of warfarin, grapefruit or pomelo with red yeast should be avoided, and ask your doctor or pharmacist first if you have liver, kidney problems or during pregnancy.

已有林志輝博士主導的研究報告證實市售中藥材與紅麴米大多數為M. anka(即M.purpureus)紅麴菌種,少數為M. pilosus/M. ruber(同物異名)。 該研究團隊104、105與106年度科技部計畫研究結果顯示M. pilosus/ M. ruber的citrinin (橘黴素)與 monacolin K 生合成能力與M. purpureus相反。M. purpureus 具有生合成citrinin 的能力,但M. pilosus/M. ruber不會產生citrinin,而M. purpureus 不會合成 monacolin K ,僅有M. pilosus/M. ruber會產生monacolin K。由於此二種麴菌皆能生產黃色素(monascin與ankaflavin)等紅麴色素,因此不會生產monacolin K 的紅麴菌M. purpureus,其主要功效成分物質很有可能為黃色素monascin與nkaflavin (Lee et al., 2010)。 礙於商業考量,民眾並不知情。貴站為專業人士,應知商業操作致西藥成分(菌種不同且製程不同)淪為健康食品的主要有效成分,實不應該。全世界似乎只有美國FDA堅持其分際予以處分禁用。
As your reference: https://www.nccih.nih.gov/health/red-yeast-rice 美國禁用食品中*含過量*monacolin,大多紅麴保健品仍以此為主要成分。這兩點台灣也相同。