By late August, the Jerusalem artichokes in one corner of the garden have shot up past head height. At the tips of the stalks, small yellow flowers that look like miniature sunflowers are opening one by one. While they bloom, the tubers underground are fattening up. Harvest is still about two months away, but now is a good time to learn what's building up inside them.
A Soluble Fiber Stored Underground
Jerusalem artichokes (also called sunchokes) and chicory take the sugars their leaves produce and store them in their roots as inulin instead of starch. Inulin is a water-soluble dietary fiber, and human digestive enzymes can barely break it down. So it passes through the stomach and small intestine largely intact and reaches the large intestine, where gut bacteria ferment it. That's why inulin tastes about one-tenth as sweet as sugar yet contributes almost no calories.
Jerusalem artichokes are native to North America and are now widely grown in Europe and Asia as well. Their knobby tubers resemble potatoes, but the plant actually belongs to the daisy family, the same family as the sunflower. Chicory is grown widely in Belgium, the Netherlands, France, and India, and most of the inulin added to packaged foods is extracted from chicory root.
What Changed in 12 Weeks
In one clinical trial, researchers added this fiber to a food, had participants eat it for 12 weeks, and tracked how their bodies changed. The 50 participants were women in their 20s through 50s with a body mass index (BMI) of 27 or higher or a waist measurement over 80 cm. They were split into two groups: one ate 200 g a day of tapioca pearls made with inulin, and the other ate the same amount of a control food that looked identical. Neither the participants nor the people handing out the food knew which group was getting the inulin.
After 12 weeks, the inulin group showed reductions in body weight, BMI, body fat mass, and visceral fat. Their total cholesterol and LDL cholesterol dropped as well. That said, the study involved just 50 people over 12 weeks. Other research has repeatedly found that a higher-fiber diet helps with managing body fat, but it's still too early to claim that any single food will make you lose weight. It's better taken as a good reason to add a bit more fiber to your meals.
From Planting to Plate
Jerusalem artichokes thrive without much fertilizer, even in poor soil. In the Northern Hemisphere, plant the tubers 10 cm deep in March or April, and start digging them up in late October, after the first frost. Because they grow taller than 2 m, try planting them along the north edge of your garden so they won't shade your other crops. Any pieces left in the ground at harvest will sprout again the following year, so it's wise to give them a dedicated spot where they can't spread.
- Raw: Scrub them well with the skin on and slice them thin for a crisp, crunchy bite. Try cutting them into matchsticks and tossing them into a salad.
- Cooked: Steaming or roasting breaks down some of the inulin, which brings out their natural sweetness.
- Dried: Slice them thin, let them dry, toast them lightly in a pan, then steep them in hot water for a tea.
Eating a lot right from the start can leave you gassy or bloated, since this fiber ferments in the large intestine. Start with about a handful a day, see how your body responds, and increase the amount gradually. If you have a sensitive gut, go even more slowly.
If you plan to dig tubers this fall, hill up some soil around the base of the stalks today. As the tubers swell, this keeps them from pushing up through the surface and turning green.
Reference — Journal of Food and Drug Analysis, clinical trial on the effects of inulin-supplemented tapioca pearls on body fat in women with obesity
