SINGAPORE: Health supplements containing red yeast rice have been in the spotlight in recent days after Japan recalled three products that could be linked to five deaths and more than 150 hospitalisations.
The three products made byKobayashi Pharmaceutical contain“beni koji”, or red yeast rice, which is said to be able to lower levels of bad cholesterol.
Japanese authorities are still investigating whether the products caused the deaths, including a suspected link to their effects on the kidneys.
What is red yeast rice, its purported health benefits and potential side effects? CNA finds out from the experts.
What is red yeast rice?
Red yeast rice is produced by the fermentation of mould on rice, said Ms Janie Jeffy, a senior nutritionist and executive committee member of the Singapore Nutrition and Dietetics Association.
This fermentation process produces the reddish-purple colour that gave the ingredient its name, she added.
According to the US National Center for Complementary and Integrative Health, depending on the strain of yeast and the conditions of fermentation, the process can cause the yeast to enrich the rice with a substance called monacolin K, which is a type of statin that can lower cholesterol levels.
What products contain red yeast rice?
Red yeast rice can be found in a wide range of products for various uses.
It is used mainly in health supplements to help people lower their cholesterol levels. These include popular supplements HypoCol and Eu Yan Sang’s CholesFREE PLUS with Natto, which are sold in Singapore.
The threeKobayashi products that were recalled in Japanare not sold in stores or official websites in Singapore,the Health Sciences Authority (HSA) told CNA.
"To date, there has been no report of serious adverse events suspected to be associated with the use of red yeast rice in health products that are available locally," HSA added.
In culinary products, red yeast rice is used to help extend the shelf life of certain foods and also as a colouring agent, explained Ms Jeffy.
What are the purported benefits of red yeast rice?
Health supplements containing red yeast rice are often marketed to help with lowering cholesterol.
This is because red yeast rice contains a compound called monacolin K, which is chemically identical to lovastatin, said Professor Eric Chan, a pharmaceutical scientist at the National University of Singapore’s (NUS) Department of Pharmacy and Pharmaceutical Sciences.
Lovastatin belongs to the class of medications called statins. Statins lower the amount of “bad cholesterol” and fat in the blood as well as increase the amount of “good cholesterol”.
According to Singapore’s HealthHub website, high “bad cholesterol” levels can cause blood vessels to clog up and lead to chest pain, heart attack or stroke.
Past research has shown that the levels of monacolin K can vary across red yeast products, said Prof Chan, but such products rarely declare the levels of the compound that they contain.
As a result, it is possible that the effectiveness and side effects of such products might be “unpredictable”, he added.
What are some of the concerns surrounding red yeast rice?
According to a 2018 study by the European Food Safety Authority, there have been reports of people in Europe and the United States experiencing side effects after consuming red yeast rice. These included muscle pain, liver injury and gastrointestinal disorders.
While monacolin K in red yeast rice helps to lower cholesterol, it also causes side effects that are similar to those from statin medication, explained Prof Chan.
Statins may cause muscle injury, with symptoms of increasing severity, such as weakness, soreness and cramps, he said. In some cases, it can lead to kidney damage.
“This is why statins are ‘by prescription only’ with recommendations to schedule safety tests on a regular basis,” he said.
However, such side effects are “uncommon” for patients taking statin medication, said Professor Yeo Khung Keong, CEO and a senior consultant with the Department of Cardiology at the National Heart Centre Singapore. About 3 per cent to 5 per cent of his patients get muscle aches and pain, he added.
Unlike statin medication, over-the-counter health supplements such asthose containing red yeast rice undergo“less rigorous”regulatory controls, said Prof Yeo.
Medication is subject to a degree of scrutiny that ensures its active ingredients are replicated in every pill.
"It must be clear what active ingredient the drug contains. And whether this active ingredient is in a particular dose that is known can be replicated," Prof Yeo explained. "Meaning it can be reliably known that if you take a pill that says 20mg of statin, it is always - within a certain margin of error - 20mg of statin."
Are there safety guidelines for redyeast rice products?
According to HSA’s regulatory guidance, supplements with red yeast rice are required to contain less than 1 per cent of lovastatin.
"Health supplements containing red yeast rice may contain trace amounts of naturally occurring lovastatin or monacolin K that is produced during the fermentation process, but must not contain added lovastatin,"a spokesperson said in response to CNA's queries.
"Dealers should perform routine testing on the finished products in accordance with the Health Sciences Authority’s guidelines for testing of health supplements, to ensure that the products meet appropriate safety and quality standards."
On its part, HSA said it conducts "regular surveillance" of health supplements in the market, including sampling of products for testing to check that they comply with safety and quality requirements.
"This includes screening for potentially harmful contaminants and medicinal ingredients," it added.
HSA noted that health supplements cannot contain medicinal ingredients and toxic heavy metals above allowable limits.
What went wrong in the case of the three Kobayashi products?
Prof Yeo pointed out that in the case ofKobayashi Pharmaceutical’s recalled products, the side effects might have been caused by a contaminant, rather than the active ingredient.
The Japanese drugmaker has saidit found what appeared to be potentially toxic puberulic acid at its Osaka factory.It could have been produced by the blue mould penicillium in the red yeast rice produced between last April and October at the factory.
Under certain circumstances in the fermentation process, the mould used in the production of red yeast rice can also produce citrinin, a toxin associated with various adverse health effects like liver damage and kidney failure, said nutritionist Ms Jeffy.
“As much as possible, manufacturers would attempt to control the citrinin levels in their products but, nevertheless, (they) cannot control a lot of environmental factors which could result in the inconsistent level of these toxins,” she added.
Related:
Japanese authorities inspect second Kobayashi Pharma factory after deaths
How safe are red yeast rice health products?
HSA said that there have been no reports of serious adverse effects associated with red yeast rice supplements that are available in Singapore.
Three non-serious adverse events were reported between 2010 and 2019 for other health products containing red yeast rice, unrelated to the recent recall in Japan. These include allergic reactions such as rash and eye swelling, as well as heartburn, nausea or vomiting.
HSA said it will continue to monitor the situation closely, and that any health products found to be unsafe will be pulled from the market.
"HSA has also issued an advisory to dealers of health products containing red yeast rice to emphasise the importance of maintaining records of the manufacturers of active ingredients of their products to ensure traceability and enable swift action if any issues arise," the spokesperson added.
Prof Yeo said he does not recall any of his patients experiencing severe side effects after taking supplements with red yeast rice. However, his recommendation is for patients to take statin medication instead.
“If you want to take a particular supplement for an active ingredient that is medically available, you might as well go for the medically available one,” he said.
“The unregulated health supplement would subject one to exactly the risk of what’s happened in Japan … where you really don’t know what goes into it.”
Prof Chan said it is “relatively difficult” for consumers to evaluate the safety of products containing red yeast rice since there are too many factors to consider.
People need to weigh the possible benefits of taking health products containing red yeast rice against the possible side effects, added Ms Jeffy.
Red yeast rice might not be safe for everyone, she noted, adding that people who have pre-existing conditions like kidney disease, liver disease or muscle disorder should not be taking such products.
Those who are taking certain medications, such as antibiotics, should also avoid such supplements to prevent interactions between the drugs.
“If you are pregnant and breastfeeding, then you should refrain from using this type of product because of the lack of safety data,” she added.
