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Mulberry Leaves: The Medicine Growing Right Above the Berries

Here we go round the mulberry bush, the mulberry bush, the mulberry bush. I loved that song as a child, all of us holding hands and spinning in a circle until somebody fell down laughing, and I loved the mulberry bush as it felt like a cousin of Weeping Willow where you could hide under dangling branches. It was magical to me,. Funny how a plant can sit quietly in the back of your heart for a lifetime and then come knocking. Lately the mulberry has come back to me as I was doing some research for a client and came across some cool information that I did not know.

Most people don’t know that the mulberry leaf is the whole reason we have silk. The silkworm eats almost nothing else, and its Latin name, Bombyx mori, means the silkworm of the mulberry tree. For thousands of years people in China raised these little creatures on mulberry leaves, and each one spins its cocoon from a single unbroken thread that can stretch more than a kilometer long. The white mulberry even came to America with the colonists, who dreamed of a silk industry here, and while that dream faded the trees stayed and spread into fields and roadsides all across the country. But here is the part I love most. Living inside the silkworm’s gut are friendly bacteria that make an enzyme called serrapeptase, and when the moth is ready to be born, that enzyme dissolves a doorway right through the silk so it can crawl out into the world. I wrote all about this remarkable enzyme in my serrapeptase article. Microbes, once again, doing the quiet and sacred work.

What I didn’t know was those silkworms know what they’re eating is a good medicine. Mulberry leaves have fed silkworms and farm animals for thousands of years because they are so full of nourishment, and when I started reading the numbers I was honestly surprised. Dried mulberry leaves can be anywhere from 15 to over 30 percent protein, which is more than cabbage or bok choy, and they are rich in calcium, iron, magnesium, zinc, vitamin C, and beta-carotene. They also carry rutin, quercetin, and chlorogenic acid, the same kinds of protective plant compounds we love in green tea and dark berries.

But where the mulberry leaf really shines is blood sugar. The leaves hold a natural compound called DNJ, short for 1-deoxynojirimycin, a name I am happy to never say out loud again.

DNJ looks so much like a sugar molecule that it gently slows the enzymes in our gut that break carbohydrates down into glucose, so instead of sugar from a meal rushing into the blood all at once, it trickles in slow and steady. And you know where the tree keeps it? Snap a mulberry leaf and watch that milky white sap bead up along the veins. That sap is where the DNJ is concentrated, and I learned it’s how the mulberry protects itself, because any caterpillar that tries to eat the leaves gets put on a forced diet. The silkworm is the one creature that found its way around it, which is why it gets to feast on mulberry leaves all day long. I love that. Nature is so clever, and so generous with us when we pay attention.

The research has been catching up to what the old healers already knew. There was a trial in England where people who took mulberry leaf extract along with a big dose of sugar had a blood sugar rise about 40 percent lower than when they took the sugar alone, and their insulin peak dropped by about the same amount. I also learned that people with prediabetes and type 2 diabetes have seen smaller spikes after meals and better long-term blood sugar when mulberry leaf became part of daily life. The leaf helps the heart as well. I read that a gram of mulberry leaf powder three times a day for a month brought total cholesterol down 12 percent and LDL down 23 percent, while the good HDL went up 18 percent. I find it beautiful that one humble leaf can help blood sugar and cholesterol at the same time, because those two so often walk together.

Then there is the gut, and you all know how I feel about our microbes. Because DNJ slows how quickly carbohydrates are absorbed, some of those carbs travel on into the large intestine, where they become food for the beneficial bacteria living there. So the same leaf that feeds the silkworm, whose own gut bacteria make serrapeptase, ends up feeding the microbes in us. Everything is connected, it always is.

The leaves are lovely for the skin too, since they hold a compound called mulberroside F that slows down tyrosinase, the enzyme behind dark spots and uneven tone, and that is why mulberry shows up in so many natural skin-brightening creams. You can make a lovely mulberry leaf cream right in your own kitchen, and I’ve put the recipe at the end of this article so you can try it for yourself.

Long before anyone measured DNJ, Chinese herbalists were using mulberry leaf, which they call sang ye. It’s written into the Shennong Bencao Jing, one of the oldest herbal texts in the world, and it’s known as a cooling herb, bitter and a little sweet. Traditionally it’s used to clear what they call wind-heat, the kind of cold that comes with a sore throat, fever, and a dry cough, and it is the lead herb in a classic formula called Sang Ju Yin, paired with chrysanthemum. Sang ye is also used for red, tired eyes, and for something the old texts called wasting thirst, with heavy thirst, hunger, and frequent urination. That sounds an awful lot like diabetes to me, and it makes the modern research feel like science finally catching up to the wisdom of the ancestors. The Chinese prize the leaves picked after the first frost, called frost mulberry leaf, while I learned that the young leaves at the branch tips carry the most DNJ during the growing season. So I say gather both. Young leaves in late spring and summer for your blood sugar tea, and frost-kissed leaves in autumn for a cold-season remedy.

The best part is how simple it is to bring these leaves into your kitchen. Tea is best because it’s easy and it’s the form most of the research points to. Put a teaspoon or two of dried leaves, or four or five fresh ones torn up, into a mug, pour hot water over them, and let them steep eight to ten minutes. It tastes mild and grassy with a little sweetness, no caffeine at all, and the time to drink it is with your meal or just before you sit down, because the leaf works on the food in your belly. A cup next to a plate of pasta or a slice of fresh bread is just right. In Japan, where mulberry tea is everywhere, people often simmer a couple of tablespoons of dried leaves in a quart of water for ten minutes and let it sit another ten for a deeper brew. And the DNJ holds up beautifully to heat, so nothing is lost in the cup.

If you want to go further, dry a big batch of leaves until they crumble, in a dehydrator on low or spread out in a warm airy room for a few days, then grind them into a green powder. I like the idea of half a teaspoon stirred into a morning smoothie, oatmeal, yogurt, or soup, and more as you grow to love it. The young tender leaves of late spring are wonderful as a cooked green too. Pull out the center vein, boil them three to five minutes to soften them and take away the slight bitterness, then sauté them in olive oil with garlic and a pinch of salt the way you would spinach or chard.

It amazes me that the bush I sang to as a child has been offering us so much this whole time. Food for the silkworm that gave the world silk, a home for the microbes that make serrapeptase, gentle help for our blood sugar and our hearts, and real nourishment we can pick right off the branch. I feel so grateful when a plant from my childhood comes back around like this, asking to be seen again. Next time you pass a mulberry tree, stop for a moment and look at those leaves. Maybe sing a little, too. And if you enjoy finding the medicine in the living world around you, you’ll find much more of it in my books on Amazon.

Did You Know?

You won’t find the true silkworm living on mulberry trees here in Ecuador, or anywhere in the wild for that matter. After thousands of years of being raised by people, it can no longer survive on its own without someone feeding it mulberry leaves. But Ecuador has its own wild silk moths, more than 200 species of them, and one of my favorites is called cuatro ventanas, four windows, because each of its wings has a little clear oval you can see right through. Its caterpillar grows to about the size of your thumb and then spins a big cocoon that often hangs from a twig on its own silken rope. If you’re out walking and spot one dangling from a branch, take a moment, because you’re looking at a cousin of the silkworm.

If you find one, feel it gently. A firm, heavy cocoon still has a moth sleeping inside, so leave it be, or snip the twig and hang it somewhere shaded in a mesh bag to watch it hatch, which usually takes three or four weeks. These moths come out at night and never eat as adults, so let yours fly free on the first evening. An empty cocoon is light and papery with an opening at one end, and that one is yours to play with. Simmer it gently in water with a spoonful of washing soda or a little mild soap to soften the natural gum, and the layers will loosen into a rough, textured wild silk you can spin by hand, stretch into a little silk hankie, or press into handmade paper. When the Spanish arrived in Mexico, people there were already gathering wild cocoons and spinning them into precious cloth, and the Yaqui still use wild silk moth cocoons to make the rattles their deer dancers wear. Our ancestors knew these treasures all along.

Homemade Mulberry Leaf Cream

The goodness in mulberry leaves for the skin dissolves in water and glycerin rather than oil, so instead of an infused oil, the trick is to first make a mulberry leaf glycerite and then whip it into a simple cream. It takes a little patience while the glycerite steeps, but the cream itself comes together in about twenty minutes, and it is such a joy to use something on your face that you made from leaves you picked yourself.

Mulberry leaf glycerite

  1. Fill a clean jar about halfway with dried, crumbled mulberry leaves.
  2. Cover them completely with a mix of 3 parts vegetable glycerin to 1 part distilled water, leaving about an inch of liquid above the leaves.
  3. Cap it and keep it somewhere warm and dark for about 4 weeks, giving it a shake every day or two.
  4. Strain through a cloth and squeeze out every drop. You’ll have a sweet, green-gold extract that keeps for a year or more.

The cream (makes a small 100 g jar)

Water phase:

  • 60 g strong mulberry leaf tea (2 tablespoons dried leaf steeped in a cup of water for 15 minutes, strained and cooled)
  • 10 g mulberry leaf glycerite

Oil phase:

  • 15 g light oil, such as sweet almond, jojoba, or apricot kernel
  • 8 g shea or cocoa butter
  • 6 g emulsifying wax, such as Olivem 1000 or e-wax NF
  1. Set the two phases in separate heatproof jars in a pan of simmering water and warm them both to about 70°C (160°F), until the wax and butter are fully melted.
  2. Pour the water phase into the oil phase and blend with a small stick blender or milk frother for a minute or two.
  3. Stir now and then as it cools, and watch it thicken into a soft, silky cream.
  4. Spoon it into a clean jar.

Because this cream is made with fresh tea, I keep it in the fridge and use it up within a week or two, which feels just right for a little homemade batch. If you’d like it to last a few months, add a natural cosmetic preservative such as Leucidal or Geogard at about 1 percent. And if you want something even simpler, a few drops of the glycerite mixed with rosewater and patted on after washing your face is a sweet little ritual all on its own.

Further Reading

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