White mulberry, or morus alba, an herbal supplement once touted by Dr. Oz as “the newest health sensation” was recently linked to the death of Lori McClintock, wife of Rep. Tom McClintock (R-Calif.).
McClintock died on Dec. 15, 2021 at age 61 after complaining of an upset stomach the day before, a Sacramento County coroner’s report noted. That report concluded that McClintock had died from dehydration due to gastroenteritis, caused by “adverse effects of white mulberry leaf ingestion.”
The autopsy report, reviewed by MedPage Today, showed a “partially intact” white mulberry leaf in her stomach.
It remains unclear how the professional conducting the autopsy knew the leaf was white mulberry, where McClintock obtained the leaf or herbal supplement, and what other health conditions may have played a role. According to Kaiser Health News, her husband said she was “safely dieting.”
The supplement is thought to be relatively safe, but it’s probably not on most clinicians’ radars. So here’s what’s known about white mulberry.
Available Forms
White mulberry leaves, root bark, and fruit have all had various uses throughout history, and can also be further processed into extracts, teas, powders, or oral supplements.
Currently, white mulberry is common in soft-gel capsules, tablets, powders, and liquid extracts. It’s available as an herbal supplement online or over the counter, or from practitioners of naturopathy, and traditional and alternative medicines.
“Traditionally, white mulberry has been consumed as an extract,” said Pieter Cohen, MD, of Cambridge Health Alliance, who studies supplement safety. “Meaning, you put the leaves in water or some other substance, and then you use that extract fluid to treat various conditions. It’s been used for years.”
Traditional Uses
White mulberry has a long history of use, cultivated as a key food for silk worms, and also in traditional Chinese medicine for over 4,000 years. Various parts of the mulberry tree, including the root bark and leaves, have been used as a pain reliever, sedative, antiphlogistic, diuretic, expectorant, and a blood pressure-reducing agent.
In addition, the extraction from white mulberry leaves has been used as a throat gargle to relieve inflammation, and the mulberry fruit has been used to treat weakness, fatigue, and anemia. Extracts have also been used to restore normal levels of blood glucose after eating.
The Chinese Ministry of Health and the Taiwanese Bureau of Food Safety both recognize the leaves as a food and medicine.
Physiological Effects
Research has suggested that mulberry leaf extract can lower blood glucose, reduce insulin response levels, and has some hypolipidemic effects in people with type 2 diabetes. The extract and tea have also been shown to inhibit digestion in rats, and purified mulberry compounds have suppressed weight gain in mice. There also may be a “prebiotic” effect — an increase of carbohydrate fermentation in the lower intestine — from mulberry extract when taken with sucrose.
Some researchers are interested in evaluating it as a target for drugs that treat type 2 diabetes, but according to one study, “the interpretation of the clinical relevance of the effects of ME [mulberry extract] has been challenging due to limitations including study design and small numbers of subjects,” and more high-quality randomized controlled trials are needed. Furthermore, as another study noted, white mulberry’s “underlying mechanism remains largely unsolved.”
Potential Side Effects
According to a study that investigated side effects from mulberry extract, 62% of those who received 125 mg experienced “one or more gastrointestinal symptoms,” including nausea, abdominal cramping, distension, and flatulence.
However, according to various studies, and to Cohen, side effects are mostly minimal and the supplement is relatively safe.
“I’m not aware of any safety concerns about the use of white mulberry,” Cohen said. “So, I would be shocked if this were just someone who was using a white mulberry extract and became sick and died from it.”
Moreover, he noted, ingesting the leaves themselves isn’t common.
But as with any over-the-counter supplement, regardless of the circumstances around McClintock’s death, “some things that are purportedly sold as botanical supplements are not what they appear to be,” he added. “They can contain the wrong plant and they can also contain untested and unproven drugs. And those substances, especially in combination, can be powerful enough and dangerous enough to kill people.”
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