White mulberry leaf is a popular dietary supplement that is used by some people with type 2 diabetes that believe it can help with blood sugar control. It has a long history of consumption in various forms as natural medicine.
Last month, white mulberry leaf briefly became the focus of national attention when a California coroner determined that Lori McClintock, the wife of congressman Tom McClintock, had died due to her consumption of the product.
Is white mulberry leaf dangerous? And does it actually do anything for diabetes?
The Lori McClintock Incident
Lori McClintock died in December 2021. At the time, no details regarding the circumstances of her death were made available. Last month, the Kaiser Health News released a copy of the coroner’s report. The cause of death? Dehydration due to gastroenteritis and “adverse effects of white mulberry leaf consumption.”
The news caused quite a stir, and people that were already taking white mulberry leaf understandably wanted to know if there was a risk of death that they were previously unaware of.
Mulberry leaf can cause gastrointestinal distress, but it was not previously known to scientists as a potentially deadly substance. As a result, experts seem doubtful that the coroner’s conclusion was appropriate. In an interview with Everyday Health, for example, Pieter Cohen, MD stated that he found it “very improbable that white mulberry leaves by themselves would lead to a death from dehydration.”
It should be emphasized that even if the cause of death was accurately ascertained, it’s possible that Mrs. McClintock’s case was highly irregular. The coroner found a “partially intact” white mulberry leaf in the stomach, which could not have resulted from the use of extracts, powders, or pills, and was perhaps unlikely to result from the consumption of white mulberry leaf tea, which would generally be strained.
Later reporting showed that the partially intact leaf, which had been identified by a curator at UC Davis’ Department of Plant Sciences, “was likely ingested when fresh.” Had Mrs. McClintock been purposefully ingesting leaves? If so, her behavior had little in common with the standard use of white mulberry leaf as a medicine.
The basic takeaway here which we gleaned from multiple expert statements on the subject, is: No, white mulberry leaf is probably not dangerous when taken as a tea or supplement, though some gastrointestinal discomfort may result.
White Mulberry Leaf and Diabetes
Does white mulberry leaf help diabetes? The answer is … maybe.
Several studies have suggested that mulberry extract, when taken with meals or doses of sugar, can help lower postprandial glycemic spikes. These include small randomized controlled trials performed in 2007, 2017, and again in 2017. Although the benefits were statistically significant in all three trials, they were also transient and modest, as none of the studies found that fasting blood glucose or A1C had improved. The theory expressed in the 2007 study is that mulberry leaves suppress blood sugar spikes by inducing sucrose malabsorption.
There is also evidence of greater benefits to rodents. A 2019 study, for example, found that mulberry leaves helped obese mice lose weight and improve their insulin sensitivity.
There are many other potential uses of mulberry leaves, including as anti-inflammatory and anti-hypertensive supplements. There have been many studies of such effects, as described in this expansive 2021 review, but these too are typically small studies that authorities have found unconvincing.
All told, the scientific evidence may be considered encouraging, but not even close to definitive. These studies were quite small and tested different formulations and different amounts ingested with different protocols. Diabetes authorities would need to see much larger, longer, and more rigorous experiments before they validate mulberry leaves’ anti-diabetic effects. Everyday Health concluded that “the evidence is insufficient to formally recommend white mulberry leaf” for the treatment of diabetes or any other condition.
The science is one thing, but we also put a lot of weight in the experiences of real people with diabetes. Diabetes is a profoundly data-driven health condition; if a supplement has a significant effect on blood sugar, it will be visible on your glucose meter.
We took a stroll through the Diabetes Daily forum archives, and a few other online diabetes communities, to see what people thought about white mulberry leaf. The truth is that there’s not a lot of chatter out there about it. We have a high opinion of our readers and community members, many of whom have sharp analytical approaches to treating their condition. The lack of discussion on white mulberry leaf suggests to us that maybe there’s not much to it. Nevertheless, it’s worth noting that mulberry leaf is more popular in Asia, where it originally grew, and that our informal sample of anecdotes was by no means reflective of everyone with diabetes.
Despite the research that has been done and the centuries of traditional use, white mulberry leaf remains something of an unknown. Like other dietary supplements, it is not regulated by the FDA, and therefore just is not subjected to the type of rigorous experimentation that pharmaceuticals are. Both the side effects and benefits are necessarily a matter of conjecture.
Read more about A1c, insulin, Intensive management, supplements, U.S. Food & Drug Administration (FDA).