Islamabad - Budding chefs eager to cook up healthy meals for friends and family face a barrage of conflicting advice.

There are advocates of the raw food diet, who abhor the thought of cooking. And then there are those who believe black pudding to be the latest super food. But, now a team of Spanish scientists have added a new theory to the mix.

They suggest frying vegetables is a healthier alternative to boiling - as long as the cook is using extra virgin olive oil. Their study found the cooking method increases the antioxidant capacity and phenolic fraction present in raw vegetables typical of a Mediterranean diet.

These compounds, the researchers said, help prevent chronic diseases including cancer, diabetes and macular degeneration. A new study, by scientists in Spain, has found frying vegetables in extra virgin olive oil is healthier than boiling them. Researchers found the oil increases the levels of cancer-fighting antioxidants, and phenols, also linked to preventing chronic diseases, including cancer, diabetes and macular degeneration Professor Cristina Samaniego Sánchez from the University of Granada, said: ‘Oil increases the amount of phenolic compounds in vegetables, which is the opposite to boiling.

‘Therefore, we must stress that frying and sautéing conserve and enhance the phenolic composition.’

The Mediterranean diet is characterized by a high intake of vegetables and extra virgin olive oil. These are both an important source of dietary phenols - compounds linked to the prevention of chronic diseases. This kind of antioxidants can be modified during the cooking process, increasing or decreasing their concentrations. The researchers set out to discover whether the choice of cooking medium – olive oil, water, or a mixture of both – had any effect on the amount of these helpful compounds in the cooked food. They conducted an experiment, cooking 120 grams of potato cubes, pumpkin, tomato and eggplant - all without seeds or skin. They used three cooking methods - frying, boiling and cooking with a mix of extra virgin olive oil and water.

In the laboratory, the samples were tested by high-performance liquid chromatography to measure levels of moisture, fat, dry matter and the total number of phenols, as well as the measurement of antioxidant capacity.

Their results revealed that using extra virgin olive oil for frying vegetables increases their fat content and reduces their moisture, while this was not observed in other cooking methods.

The scientists said the extra virgin olive oil increases the level of phenols in the vegetables, because they are transferred from the oil to the vegetables during the cooking process. They did warn the cooking process does increase the vegetables’ ‘energy density’ - or calorie content

Professor Samaniego said: ‘Comparing the content of phenols with that of raw vegetables we found increases and reductions alike, depending on the chosen method.

‘Oil as a mean of heat transfer increases the amount of phenolic compounds in vegetables, opposite to other cooking methods such as boiling, where heat transfer is done through water.’

She said the extra virgin olive oil transfers phenols to the vegetables, adding those which are not present in raw vegetables.

‘Therefore, we can confirm that frying is the method that produces the greatest associated increases in the phenolic fraction, which means an improvement in the cooking process although it increases the energy density by means of the absorbed oil,’ Professor Samaniego said.

How food packaging chemical could lead to weight gain

While the food we eat can influence health, new research suggests we should also turn our attention to the packaging it comes in, after revealing how exposure to a chemical commonly used in plastics for food packaging and other products may lead to weight gain.

Researchers found exposure to DEHP - a chemical often found in food packaging - led to weight gain in female mice.

Martin von Bergen, head of the Department of Molecular Systems Biology at the Helmholtz Centre for Environmental Research (UFZ) in Germany, and colleagues found that the chemical di-(2-ethylhexyl)-phthalate (DEHP) led to a hormone imbalance in female mice that triggered weight gain, even when exposed to the chemical in low concentrations.

The team - including researchers from the University of Leipzig and the University Hospital Leipzig, also in Germany - recently published their findings.

DEHP is a type of phthalate, or plasticizer, that is added to plastics to make them more soft, flexible or sturdy. As well as in food packaging, phthalates are present in some children’s toys, medical tubing, vinyl flooring, adhesives, and even in some personal care products - such as nail polish and shampoo.

However, ingesting foods that have come into contact with phthalate-containing packaging is the most common way we are exposed to the chemicals, and numerous studies have associated phthalate exposure with health problems.

Previous research has also suggested phthalate exposure may lead to weight gain, but von Bergen and colleagues say little is known about the mechanisms underlying this association - something they set out to uncover with this latest study.

The team reached their findings by exposing mice to DEHP. They added various concentrations of the chemical to the animals’ drinking water for 10 weeks and assessed how it impacted weight, comparing the effect with mice that were not exposed to DEHP.

Both groups of mice consumed standard chow over the 10-week study period.

The researchers found that female mice exposed to DEHP gained significantly more weight than non-exposed female mice. Weight gain was even identified among mice exposed to low concentrations of the chemical, though no such association was found in exposed male mice.

On assessing the metabolic products in the blood of the female mice, the team identified an increase in expression of estrogen receptors and reduced expression of Pparg receptors in adipose tissue, which they say could contribute to changes in metabolism that cause weight gain.

Commenting on what their findings show, von Bergen says:

“It is evident that phthalates seriously interfere with the hormone balance. They give rise to significant changes, e.g. weight gain, even in low concentrations.”

He notes that some metabolic changes mediated by activity in adipose tissue can also influence functions in other organs. “However,” von Bergen adds, “there is no conclusive clarification of how the various effects of phthalates on metabolism influence each other and ultimately lead to weight gain.”

The team plans to continue investigating how phthalates affect metabolism, as well as assess how the chemicals influence the development of diseases in early childhood.