Interview with Metin Uyar, PharmD

This interview was published in Hürriyet Newspaper on December 3, 2022 in Turkish (click here to read it on the newspaper’s website). I would like to thank the dear Metin Uyar, PharmD, who turned our pleasant conversation into a newspaper column, and the dear Assoc. Prof. Hilal Bardakçı, PhD, who introduced us.

Beware of Adulteration in Oils!

Metin Uyar, PharmD & Assoc. Prof. Nilüfer Orhan, PharmD

A recent study published in the United States (Nigella Bulletin) revealed widespread adulteration of nigella (Nigella sativa) oil in many countries, including Türkiye. The study shows that up to 40% of nigella oil products sold in Türkiye are adulterated. Meanwhile, sunflower oil is being sold as peppermint oil by adding menthol, and elderberry products are adulterated with purple rice or purple carrot extracts. Oil adulteration can have serious negative health consequences—sometimes even resulting in death.

In the United States, there is a nonprofit organization conducting research on herbal medicines, products, and dietary supplements: the American Botanical Council (ABC). Recently, the Council published a report exposing adulteration in botanical products. I spoke with Assoc. Prof. Nilüfer Orhan, a pharmacognosy expert working within ABC’s relevant program, to learn more—particularly about fraud in nigella oil.

It turns out that nigella oil, which is very popular in Türkiye, is also widely used in many countries, including the United States. According to the report, the quality of nigella seed oil varies significantly from country to country. In Türkiye, 40 out of every 100 products purchased were found to be adulterated.

Adulteration is Very Common in St. John’s Wort Oils

Assoc. Prof. Nilüfer Orhan explains:
“Adulteration can occur in all botanical products, but in Türkiye there is particularly serious fraud in essential and fixed oils.” She notes that manufacturers may mix expensive oils with cheaper ones to reduce costs. In some cases, the advertised oil may not even be present in the product at all.

“For example,” she says, “there are companies that add menthol—the compound responsible for the smell of mint—to sunflower oil and sell it as peppermint oil. It smells like peppermint, but when analyzed, it turns out not to be peppermint oil. Elderberry products are adulterated with purple rice or purple carrot extracts.”

The most commonly adulterated products include St. John’s wort, essential oils of rose, bergamot, cinnamon, lavender, lemon balm, peppermint, tea tree, sandalwood, thyme, nigella oil, and even olive oil. In some cases, chlorophyll is added to cheap oils to give them a green color and sell them as unrefined olive oil.

As a result of such fraud, products fail to deliver their expected benefits, leading consumers to lose trust in natural products and turn instead to chemical alternatives.

Another major concern is the unexpected side effects caused by adulterated products. While examining case reports related to black seed oil, Orhan shares striking examples:

“There is a black-seeded plant (Agrostemma githago) whose seeds can be confused with nigella. These seeds have been mistakenly harvested and mixed in, and historically they have caused deaths. In India, nigella and mustard oils are used as cooking oils. In 1998, these oils were adulterated with oil obtained from another plant (Argemone mexicana). As a result, 3,000 people became ill—most of them children—and 65 people died. Extreme caution is necessary.”

“Approved by the Ministry of Health”

Orhan explains that in Türkiye, dietary supplements are approved not by the Ministry of Health, but by the Ministry of Agriculture and Forestry, and that the approval process is based largely on manufacturers’ declarations.

“In other words, companies submit an application stating what the product contains—without mandatory analysis. Yet these products can have serious effects on health, just like medicines. You may recall weight-loss products marketed as ‘herbal’ that contained sibutramine and caused multiple deaths. For this reason,” she says, “it would be most appropriate for these products to be analyzed and approved by the Ministry of Health, just like medicines.”

Which Products Should We Choose?

Assoc. Prof. Nilüfer Orhan emphasizes that it is extremely difficult to distinguish genuine products from adulterated ones by sight alone:

“You cannot make this distinction visually—analysis is essential. While advertising is prohibited for herbal medicinal products, it is allowed for dietary supplements. As a result, less reliable products can stay in consumers’ minds due to strong advertising and be perceived as more trustworthy, when the opposite may be true. I therefore advise consumers to be cautious of cheap products.”

She offers the following recommendations:

Purchase fixed and essential oils from pharmacies, not herbal shops.
Choose reputable brands that develop products in collaboration with universities and conduct analyses in university laboratories.
If a product is available in herbal medicinal form, choose that option, as herbal medicines are approved by the Ministry of Health.
You can access the Council’s reports on botanical adulteration via the following website:
www.herbalgram.org/resources/botanical-adulterants-prevention-program

Adulteration Also Occurs in Spices

Botanical products are not limited to essential and fixed oils. Unfortunately, adulteration is also frequently encountered in spices, plant extracts, and other herbal products. Assoc. Prof. Nilüfer Orhan shares some examples encountered during analyses:

“Nitrogen-containing synthetic dyes are added to red chili powder; lead chromate and metanil yellow are added to turmeric to make low-quality products appear attractive. Microscopic examination of thyme spice has revealed leaves from rockrose, olive, sumac, and myrtle plants. Analyses of saffron samples have shown dyed corn silks, pomegranate peels and fibers, safflower, and calendula flower parts.

Cranberry extracts are used for urinary tract infections, and it is known that extracts from other purple-red plants—such as hibiscus, black rice, black beans, and black mulberry—are used to adulterate cranberry products.”

Many plant extracts, including cranberry, have standardized versions available in pharmacies. To obtain the expected health benefits and protect yourself from potential risks, I recommend purchasing these products in consultation with your pharmacist.

Interview with Metin Uyar, PharmD