White mulberry (Morus alba) is a fast-growing tree native to China, originally cultivated for thousands of years as the primary food source for silkworms. Today it’s found on every inhabited continent, grown both as an ornamental tree and as a source of leaves, fruit, and bark used in traditional medicine and modern supplements. The tree’s leaves have attracted particular scientific interest for their ability to lower blood sugar after meals.
What the Tree Looks Like
White mulberry is a small to medium-sized tree with a straight trunk that can reach about 1.8 meters (roughly 6 feet) in circumference. The bark is light brown to gray, smooth when young, and develops narrow scaly ridges with age. Its leaves are alternate, oval-shaped, sometimes with lobed edges, and range from two to seven inches long. The flowers are small, greenish, and hang in clusters called catkins.
The fruit resembles a small blackberry, typically white or pale pinkish violet. It’s sweet but mild in flavor, and trees produce it in such abundance that the berries often litter sidewalks and lawns beneath them. Despite the name “white mulberry,” some cultivated varieties produce darker fruit.
Where White Mulberry Grows
The tree’s original range spans much of Asia, from China and Japan through Central Asia to Turkey. Wherever silkworm farming spread, white mulberry followed. It’s now naturalized across parts of Africa, South America, Europe, and North America. In the United States, it thrives especially in urban environments, where it grows readily in disturbed soils and along roadsides. In Michigan, for example, it’s common in urban areas across the southern half of the state but rare in intact forest communities.
White mulberry’s aggressive growth habit has raised ecological concerns in North America. It hybridizes freely with the native red mulberry (Morus rubra), which can dilute the genetic integrity of that already uncommon species. In many regions, it’s considered an invasive introduction rather than a welcome addition.
Leaves vs. Fruit: Different Chemistry, Different Uses
The leaves and fruit of white mulberry contain distinctly different compounds, which matters if you’re interested in the tree for health reasons. The leaves are rich in flavonols like quercetin and kaempferol, along with chlorogenic acid. Most importantly, they contain a compound called 1-deoxynojirimycin (DNJ), which is the key ingredient behind mulberry’s blood-sugar-lowering reputation. DNJ works by inhibiting enzymes in your gut that break down carbohydrates into sugar, slowing the rate at which glucose enters your bloodstream.
The fruit, by contrast, is lower in DNJ but contains anthocyanins, the pigments responsible for dark berry colors and associated with antioxidant activity. White mulberry fruit has less anthocyanin content than black mulberry (Morus nigra), which is why it’s paler. If blood sugar management is the goal, leaf extracts are the form most studied and most commonly sold as supplements.
Nutritional Profile of the Fruit
Fresh white mulberry fruit is about 71.5% water, making it similar in moisture content to most fresh berries. Per 100 grams, the fruit provides roughly 22.4 mg of vitamin C, 4.2 mg of iron (a notably high amount for a fruit), and 1.47 grams of fiber. It also contains 181 mg of phenolic compounds per 100 grams of fresh fruit, which contribute to its antioxidant capacity.
Dried white mulberries, which you’ll find in health food stores, concentrate these nutrients by removing most of that water. They have a mild, honey-like sweetness and a chewy texture, and they’re commonly added to trail mixes, oatmeal, or baked goods.
Effects on Blood Sugar
The most studied health benefit of white mulberry is its effect on blood sugar spikes after eating. In traditional Chinese medicine, mulberry leaves have long been used to treat a condition called “Xiao-ke,” which corresponds closely to diabetes. Modern clinical trials have put this tradition to the test.
In a randomized, placebo-controlled trial of 85 healthy adults, a mulberry-containing supplement reduced the blood sugar spike after drinking a sugary beverage by about 50% in the first 30 minutes and 43% over two hours. When participants ate a carbohydrate-rich meal instead, the reduction was around 41% at one hour and 20% over two hours. These are significant reductions, particularly for the first hour after eating, when blood sugar typically peaks.
The doses used in clinical studies vary widely. Some trials have used 1 gram of leaf extract taken with a meal, others have tested 3 grams of leaf powder daily, and one study used 300 mg of extract twice per day. There’s no standardized dose, partly because the DNJ content of different extracts varies. Most supplement manufacturers recommend taking mulberry leaf extract shortly before or with a carbohydrate-containing meal, which aligns with how the enzyme-blocking mechanism works.
Cholesterol and Heart Health
A smaller body of research suggests white mulberry may also influence cholesterol and triglyceride levels. Studies have tested mulberry leaf extract in people with high triglycerides and type 2 diabetes, with some showing improvements in lipid profiles. However, these trials have been small, often involving only 10 to 30 participants, and the evidence isn’t strong enough to draw firm conclusions about cardiovascular benefits on its own.
Interaction With Diabetes Medications
If you take medication for blood sugar management, white mulberry supplements deserve caution. Because mulberry leaves lower blood sugar through their own mechanism, combining them with diabetes drugs can amplify the effect and potentially cause blood sugar to drop too low.
This isn’t just theoretical. A study on the interaction between mulberry leaf extract and metformin, one of the most common diabetes medications, found that three weeks of mulberry extract use enhanced metformin’s blood-sugar-lowering effect by about 49%. The reason: mulberry extract slowed the body’s ability to eliminate metformin through the kidneys, effectively increasing the drug’s concentration in the bloodstream by reducing its clearance rate by 50%. This means mulberry doesn’t just add its own blood-sugar-lowering effect on top of the medication. It makes the medication itself more potent, which could be dangerous without medical supervision and dose adjustment.
Traditional and Modern Uses
In traditional Chinese medicine, nearly every part of the white mulberry tree has a designated use. The leaves (Sang Ye) are used for coughs, sore throats, fever, and bronchitis in addition to blood sugar management. The root bark (Sang Bai Pi) and the fruit (Sang Shen) each have their own traditional applications.
In the modern supplement market, white mulberry leaf extract is the dominant form, sold primarily for blood sugar support. You’ll also find dried mulberry fruit marketed as a superfood snack and mulberry leaf tea, which offers a milder dose of the same compounds found in concentrated extracts. The fruit is eaten fresh in regions where the tree grows, though its mild flavor and tendency to spoil quickly mean it rarely appears in grocery stores outside of dried form.