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News Navigator: Which dietary supplements contain harmful ingredients?

A supplement containing pueraria mirifica is seen for sale online. (Mainichi/Reiko Oka)

The Mainichi Shimbun answers some common questions readers may have about supplements, and what dangers may come with taking them.

Question: I've heard a lot recently about people who take supplements and become ill. What's going on?

Answer: Supplements aren't medicine; they're actually food products. So, you can't lose weight, look younger or make your bust bigger just by taking them. Conversely, depending on who takes them and how, the products can cause harm. Standards for what must be written on product packaging are also expected to be revised in June to require manufacturers to label supplements with ingredients that require consumers' attention as food products containing or including designated components.

Q: What are the designated components?

A: The first round of designations by the Ministry of Health, Labor and Welfare is expected to apply to four component types: coleus forskohlii, celandine, pueraria mirifica and black cohosh. Their use isn't banned, but they can have strong effects on the body, and depending on a consumer's gender, age, physical health and whether they have any other conditions, it may be harmful to them.

The component which has sparked the highest number of complaints thus far is pueraria mirifica, according to the National Consumer Affairs Center of Japan. The organization said that between fiscal 2012 and 2016 it dealt with around 200 consultations on genital bleeding and menstrual irregularities concerning the ingredient.

Q: These names are a bit confusing. What does it all mean?

A: They're all plants, or what might be called medicinal plants or herbs. They're marketed as helpful for achieving beautiful skin, detoxing, reducing one's body fat percentage, and other benefits. But they can cause damage such as impairing liver functions. For example, Japan's Consumer Affairs Agency warns that women who are pregnant or lactating, or girls who have yet to have their first period, should refrain from taking pueraria mirifica.

Q: If they're going harm to people, then shouldn't they be banned?

A: It's difficult to establish a causal link between taking supplements and adverse health effects. It's not definitely the case that the four ingredients cause damage to the body, and the amounts mixed into each supplement differ. To make it easier to collect information, the health ministry has obligated supplement makers and sellers to report any confirmed cases of harm caused by the products. If it becomes clearer that they do have adverse effects, it's possible they will be banned.

(Japanese original by Reiko Oka, Lifestyle and Medical News Department)

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