Berkeley Open Source Food Project Lists Edible Urban Weeds

Tasty, nutritious and everywhere, our urban weeds may hold the key to health, food justice and equity.

Researchers from the University of California Berkeley have identified 52 edible weeds growing in abundance in the poorest neighborhoods of San Francisco, surrounded by busy roads and industrial zones.

At least six of them are more nutritious than kale, according to a new study.

The three low-income neighborhoods the researchers studied have been classified as “urban food deserts” — meaning they are more than a mile from the nearest shop that sells fresh produce.

Of the 52 species of wild-growing “weeds” they found, they tested six for nutrition content:

Chickweed

Dandelion

Dock

Mallow

Nasturtium

Oxalis

All six were more nutritious, by most accounts, than kale – arguably the most nutritious domesticated leafy greens.

The weeds boasted more dietary fiber, protein, vitamin A, calcium, iron, vitamin K, and provided more energy.

The only nutrient kale scored higher in was vitamin C, but the researchers suspect other weeds they found, such wild mustard and wild radish, might rival it in that category.

Many of the edible weeds they found have been used in folk medicine, including plantain, cat’s ear, fennel, sow thistle, wild lettuce, and wild onions.

The really exciting part about the study, is that these weeds were foraged in the middle of a drought.

“Foraged leafy greens are consumed around the globe, including in urban areas, and may play a larger role when food is scarce or expensive,” writes Philip Stark, statistics professor and founder of the Berkeley Open Source Food Project.

“Even during this low-production period, almost every address in all three study areas had several servings of several different species, suggesting that wild edible greens are a reliable source of nutrition all year round,” writes Stark.

Soil at some survey sites had elevated concentrations of lead and cadmium, but tissue tests suggest the weeds don’t take up much of these or other heavy metals.

After being rinsed, they tested at less than the dosages considered safe by the EPA, the researchers said.

Pesticides, glyphosate, and PCBs were undetectable.

How can people identify which wild greens are edible?

“Familiarity,” says Stark. “Most people have no trouble telling the difference between, say iceberg lettuce and romaine lettuce.”

He recommends people educate themselves and gradually start adding new weeds into their diets.

The report notes there are only 1.7 cups of farmed vegetables available per person per day in the United States, less than the recommended serving of two to three cups.

The researchers suggest wild food could fill in the gap and improve nutrition security.

“Wild foods might also contribute to a healthy ecosystem by building soil organic matter, retaining water and nutrients in the soil, and reducing erosion,” Stark wrote.

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