Nutrition scientists, public health experts and economists agree: The white potato — fresh, not fried — is nutritious and more importantly fills in nutritional gaps in the diets of the low-income women and children who participate in the federal WIC program.

An Institute of Medicine panel on Tuesday released its recommendation that the white potato no longer be excluded from WIC’s list of allowable fresh vegetables.

Champions of the white potato — including Maine’s two U.S. senators — are claiming victory for the tuber. It’s really a victory, though, for a scientifically rigorous process used to determine the makeup of the WIC “food package” in the face of persistent congressional intervention to force the spud’s inclusion before the scientific process played out.

WIC, short for the Special Supplemental Nutrition Program for Women, Infants and Children, issues vouchers each month — worth about $55 per participant — that allow low-income pregnant women and mothers with infants and young children to buy a narrow range of nutrient-rich foods. WIC allows $10 in vouchers for participating women and $8 for children that can be redeemed for any fresh fruit or vegetable — except, until recently, the white potato.

More than half the nation’s infants participate in WIC. In Maine, about 5,700 infants were signed up each month in 2012, along with more than 14,000 young children and 5,500 mothers and mothers-to-be, according to the National WIC Association. And WIC is successful. Participating mothers are more likely to have healthy deliveries — lowering health care costs — and infants are less likely to spend time in the hospital. Experts also give the program some credit for the 43-percent drop in obesity among 2- to 5-year-olds that has taken place over the last decade.

The white potato’s exclusion is the result of a major nutritional overhaul WIC received in 2009 — the first since WIC started in 1972. An Institute of Medicine expert panel recommended the overhaul in 2005 based on the federal government’s 2005 Dietary Guidelines for Americans. “[M]ost Americans do not need encouragement to consume the maximum recommendation of one serving of potatoes per day,” the panel wrote at the time.

This time, a similarly composed Institute of Medicine panel based its recommendation on the 2010 Dietary Guidelines for Americans, which recommend Americans increase their consumption of starchy vegetables — a vegetable type that includes potatoes but also corn, peas, lima beans and squash. In its review of the research, the panel found that WIC participants weren’t consuming the recommended amounts of starchy vegetables — though their consumption levels for dark green vegetables and red-orange vegetables were even lower.

“Overall, the nutrient profile of white potatoes was similar to that of other starchy vegetables,” the panel wrote. “Because they are widely consumed, white potatoes provide useful quantities of potassium and fiber in the diets of Americans.”

The white potato isn’t permanently included in WIC just yet. The Institute of Medicine review was an early step in a process that — under federal law — is to take place every 10 years in which scientists advise the U.S. Department of Agriculture on the makeup of the WIC food package. That process will take at least another year, and the guidance on the potato could change again, depending on the nutritional recommendations in the 2015 Dietary Guidelines for Americans, which are expected to come out at the end of the this year.

The scientific process at the heart of WIC is a critical part of maintaining WIC’s nutritional integrity and the public’s faith in the program. Congressional intervention in what should be an exercise by credentialed scientists threatens that process.

As it appears now, WIC simply needed to wait for the potato’s scientific affirmation.