This article originally appeared in the San Francisco Chronicle on November 27, 2014.
Healthy eaters looking to get the most nutrients out of their fruits and vegetables may naturally think fresh is a better choice than frozen. But that’s not always the case, say researchers in a new study from the University of Georgia.
Fresh fruits and vegetables may be best straight from the field, but by the time they’ve traveled from the farm to the store to the home refrigerator and finally to the dinner table, they may have lost their nutritious edge.
The Georgia study compared the vitamin and mineral contents of produce in three states – frozen, fresh on the day of purchase, and fresh that had been stored in a home refrigerator for five days, the average amount of time consumers said in a survey they keep vegetables before eating them.
Researchers looked at blueberries, strawberries, broccoli, green beans, corn, spinach, cauliflower and peas. In most cases, the frozen produce had as many nutrients as the newly purchased fresh samples, and sometimes more than the fresh ones kept in the refrigerator. Frozen peas had more vitamins C, A and folate than fresh peas that had been stored, and frozen corn and blueberries also topped the fresh stored folate levels.
There were a few exceptions. Fresh and fresh-stored blueberries had more vitamin A than the frozen ones. Frozen spinach had a lower vitamin C content than its fresh counterparts, and researchers suggest it might be because the frozen product had been blanched in hot water and chopped before freezing.
Cooking food in any manner – boiling, baking, steaming or microwaving – changes the food’s nutrition profile, but other studies have shown that it’s not always for the worst. (Frying is the exception; it is universally considered pretty unhealthy). Different cooking methods degrade some vitamins in certain vegetables, but they enhance others.
Experts say the more fruits and vegetables one eats, the better. The latest U.S. dietary guidelines call for between 2 1/2 to 6 1/2 cups a day, so how they are prepared is less important that whether they are eaten at all.