Although yams have been around for eons, there are so many species (over 600), it can get very confusing at times. Which are eaten and which used medicinally? Are they all similar to each other? Plus where do they grow and how are they used?
Wild yams have been an incredibly important food for much of the world. In fact, yam comes from the Senegalese word “nyami,” which means “to eat.” When coming to the Hawaiian Islands to found new settlements, the Polynesians brought 27 plants with them to help establish their lives there. As you can imagine, traveling over 2,300 miles on a double-hulled boat filled with people and livestock, supplies were limited to only what was needed. Thus, each plant was important and had a specific purpose. All they brought served as either food, medicine, cordage, tools, fabric, shelter, containers, dyes, wood, or religious purposes.
While most people are familiar with the obvious island food choices of taro, breadfruit and bananas, amongst these 27 plants there were three yam species included:
- Uhi – wild yam (Dioscorea alata) food
- Hoi – bitter yam (Dioscorea bulbifera) food during famine
- Pi’a – five-leafed yam (Dioscorea pentaphylla) food during famine
Imagine if you were traveling thousands of miles to settle a new world and could only take a few things for your survival. This is how important Dioscorea yams were and still are today.
There is much to be said about the Dioscorea family and its many wild yams. First, there’s often confusion distinguishing the many wild yams from each other. Only about 12 of the species have been traditionally eaten as a starchy alternate food for potatoes throughout the world. Slippery and slimy in texture, white in color, neutral in energy, and sweet/bland in flavor, many are great yin tonics, meaning they moisten and build fluids in the body. And although they grow as vines, it is the tuber that is used.
American and Mexican Wild Yams
American wild yam (D. villosa , D. quaternata) is native to Central and Eastern United States (except northern New England) and Mexico. During the 1970s its outer bark was investigated to determine the presence of steroidal sapogenins, such as diosgenin, to use as a substance for the birth control pill. It has since been used to manufacture progesterone. However, know that American wild yam does not work as a birth control substitute. I am aware of a dozen women who tried it and three got pregnant! Further, know that any wild yam cream that contains progesterone acts only as an emollient since the wild yam molecule is too large to pass through the skin.
Medicinally, American/Mexican wild yam is used for spasmodic, shooting and aching pains, especially due to an excited nervous system. It treats bilious colic, neuralgia, rheumatoid arthritis, hip pain (especially at night), urinary pains (especially from passing stones), menstrual cramps, and digestive problems associated with liver and gallbladder imbalances. It is a near-specific for chronic flatulence and gas and treats IBS, colitis and diverticulitis. As well, it is used for mid-cycle spotting, PMS, dysmenorrhea, nausea during pregnancy, and menopause. Most people don’t eat this wild yam because it is bitter.
Energy and flavors: neutral; sweet, bitter
Organs/meridians entered: Liver, Kidney, Large Intestine
Properties and actions: antispasmodic, diaphoretic, diuretic, expectorant, cholagogue; calms Liver Wind, regulates Qi
Chemical constituents: glycoside saponins and diosgenin (hormone
precursors, especially progesterone and other cortical steroids that affect
the menstrual cycle and reduce pain)
Dosage: 3-9g standard decoction; 10-30 drops tincture (1:5 @55%ABV), QID, or 10-20 drops every 10 minutes
Chinese Wild Yams
Wild yams are regularly eaten as food throughout much of Asia. They can even be purchased in grocery stores. The species called cinnamon vine, nagaimo or Chinese potato, D. polystachya, originated in Myanmar, India, Sri Lanka, and Bangladesh. The Chinese often eat it raw, or cooked like a potato in stews and soups. When taken raw, it tonifies yin; dry-fried, it strengthens digestion. Try purchasing it fresh from Asian markets or grow your own.
Medicinally, the Chinese wild yam used is D. oppositifolia (shan yao; formerly known as D. opposita). It is distinctly different from the North American wild yams and so does not substitute for them. Chinese yam root vitalizes the spleen-stomach digestive functions, tonifies the lungs and kidneys and consolidates the essence and sperm. It treats low energy, lack of appetite, spontaneous sweating, dry cough, asthma, diarrhea, vaginal discharge, frequent urination, nocturnal emission, and premature ejaculation. It can be externally applied to bring boils and abscesses to a head.
Energy and flavor: neutral; sweet
Organs/meridians entered: Kidney, Lung, Spleen, and Stomach.
Properties and actions: Tonic, demulcent, regulates blood sugar; tonifies Qi and Yin, stabilizes Essence, stabilizes and binds
Chemical constituents: Starch, mannan, saponins, allantoin, arginine, choline, mucilage, phytic acid, Vitamin C
Contraindications: Food Stagnation.
Dosage: 9-30g; 30-60 drops tincture (1:5 @50%ABV), TID
Note: Up to 250 g can be made into a tea, or added to food daily.
And yet more Chinese wild yams:
The Chinese also use D. collettii medicinally (bei xie; also known as D. hypoglaugae), however, it is different than the food-like yams. This one is bitter in flavor and acts like a diuretic, clearing damp heat and expelling wind-damp-heat chronic obstruction syndromes. Known as tokoro, it treats joint, muscle, and sinew pains and stiffness, eczema, sores, vaginal discharge, cloudy urine, and gonorrhea. Other Chinese wild yams include D. polystachys and D. batatas.
Japanese Wild Yam
Like the Chinese wild yam, Japanese wild yam (D. japonica) is dug up and regularly eaten. Called yamaimo, it is often grated or julienned and served with soup or stews, or cubed to eat with raw tuna. Supposedly it was considered an aphrodisiac in the Edo Period (1603-1868), called “mountain eel.” Men not only ate it but also added it to their bathwater to enhance virility. It is a close relative to their D. polystachys. Dioscorea japonica is used medicinally in very similar uses to the Chinese D. oppositifolia.
Costa Rica Wild Yam
When recently visiting Costa Rica, we found three species of wild yam growing side by side together in one space, planted in the Garden of Sacred Seeds at Finca Luna Nueva. American (D. trifola), Mexican (D. villosa), and the local (D. alata) were intertwined as if loving relatives holding hands.
We dug up the local D. alata (introduced to the Americas by the Afro-descendants in the 17th century). Never used for anything other than food, we took the huge white slippery and starchy root back to the kitchen where we cooked it into chips and later yam mash, which we found to be similar to but much better than mashed potatoes. After eating these feasts, we found we had barely made a dent into the huge root!
And what about regular yams you find at the grocery store?
Yams are delicious. Thankfully, they’re high in vitamins A, C (vital for inflammation and quick wound healing) and B (especially B6) as well as potassium and manganese, making them valuable for strengthening bones, increasing immunity and, being high in saponins, relaxing muscles and joints. They also benefit the nerves, brain, skin, hair, eyes and treat post-menopausal symptoms.
Yams are low on the glycemic index and so even though sweet, they are great for diabetes and blood sugar imbalances. There are different varieties of course, each with different skin and flesh colors. I find the Japanese sweet potato with its reddish skin and whitish flesh to be less sweet, to make a wonderful breakfast with soft boiled eggs.
And in case you’re wondering, yams are not the same as sweet potatoes as both are in different plant families (sweet potatoes are in the Convolvulaceae family).