What’s the difference between horse chestnuts and sweet chestnuts?

Chestnuts are a delicious staple of the holidays, but some types are toxic and shouldn’t be eaten.

Chestnuts can be a nutritious and delicious fall and winter treat. They can be boiled, steamed and, of course, roasted over an open fire. But some chestnuts are toxic and definitely not for eating.

National Chestnut Week is Oct. 13-19, and Michigan State University Extension wants to ensure that everyone enjoys all the great benefits that chestnuts have to offer while remaining safe by avoiding unsafe, toxic varieties of chestnuts.

The sweet chestnut is the delicious, edible chestnut that most people are familiar with around the holidays. An edible chestnut is easiest to spot if it is still in its husk, which is spiny and needle-sharp. The toxic, inedible chestnut, also called the horse chestnut, has a husk that is much smoother, with only a few warts. Horse chestnuts are the ones commonly found in forests and backyards.

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Image 1. Sweet chestnuts, like those shown here, have a distinct spiny husk that is sharp to the touch. 

Another easy way to tell them apart is to look at the nut itself. Both are brown with a light-colored spot on them. However, edible chestnuts always have a tassel or point on the nut—something that your finger can feel as a point. The toxic chestnut has no point—it is smooth and roundish all over.

Sweet, edible chestnuts are not only non-toxic but are also an incredibly healthful snack.

“Chestnuts are a wonderful treat,” said Dennis Fulbright, professor of plant pathology at Michigan State University. “They are low in fat, high in protein, gluten-free, high in vitamins and fiber, and, most importantly, they are delicious.”

That could be why there has been an explosion in chestnut growing in Michigan in the past 20 years. In 2007, Michigan had the largest number of chestnut growers and the most chestnut acreage in the United States.

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Image 2. On the left, three edible chestnuts with their tassel or point showing; and on the right, two toxic horse chestnuts without a tassel or point.

So, what is the best way to ensure that the chestnut you have is a sweet, edible chestnut?

“The first and most important consideration is to never pick up a chestnut or anything else off the ground and eat it,” Fulbright said. “Toxic horse chestnuts are often found on the ground because even animals don’t want to touch them.”

Because Michigan is the largest chestnut-growing state in the country, there are ample places to find safe, sweet chestnuts. Farmers clean, sort, size and inspect their product and ship all over the country, and safety is their top priority. Chestnuts are available at retail locations all over Michigan—at farm and farmers’ markets, and at grocery stores that have locally grown produce, including Whole Foods and Meijer.

Michigan State University and MSU Extension have been instrumental in helping this burgeoning statewide industry establish a strong, trusted international chestnut brand. The website chestnuts.msu.edu serves as a clearinghouse for the latest grower reports and news and information from university experts and Extension educators.

More information can also be found at the MSU Extension website (www.msue.anr.msu.edu) and Chestnut Growers, Inc., the Michigan chestnut growers’ cooperative (www.chestnutgrowersinc.com).