Researchers Uncover: Which Is Healthier – Frying Vegetables or Boiling Them?

A research study published in the journal Food Chemistry found that frying vegetables in oil significantly increases their antioxidant content compared to other cooking methods.

The study was conducted by a team of researchers at the University of Granada in Spain. In the study, 120-gram servings of vegetables such as potatoes, pumpkin, zucchini, and tomatoes were cooked using various methods: light frying, deep frying, boiling in water, and cooking in a mixture of water and oil.

The findings of the study showed that frying vegetables increased the levels of phenolic compounds, a type of antioxidant that helps the body fight cancerous cells, and is also effective in preventing vision impairment and diabetes.

"Oil, as a heat transfer medium, increases the amount of phenolic compounds in vegetables, as opposed to other cooking methods like boiling, where heat transfer is done via boiling water," explained Professor Cristina Samaniego Sánchez, one of the researchers who authored the study.

Frying in oil leads to the transfer of phenolic compounds from the oil to the vegetables because these compounds are only present in oils and do not naturally occur in vegetables. "For this reason, we can assert that frying in oil is the cooking method that adds the most phenolic compounds to vegetables," said the professor.

The researcher further added that: "When the raw vegetable's phenolic compound content is initially high, it increases even more if pure olive oil is used during cooking. Boiling vegetables in water, however, does not affect the final concentration of the compounds."