After adding sunflower oil, selenium and vitamin E to cattle feed, USP researchers discover antioxidant effects in children that consumed milk from the animals. Enrichment also improved conservation of the product

Antioxidant enrichment

November 9, 2011

By Fábio de Castro

Agência FAPESP
– After adding sunflower oil with organic selenium and vitamin E to cattle feed, a group of researchers from the Universidade de São Paulo (USP) studied not only the effect produced in the animals themselves but also in the children that consumed the milk.

The results showed that, aside from offering health benefits to the cows and increasing milk production, the enriched feed improved the conservation of the product and increased levels of selenium and vitamin E in the blood of children that drank the supplemented milk.

The study, which received FAPESP funding under its Regular Research Award program, was coordinated by Marcus Antonio Zanetti, a professor in the Zootechny Department in the USP School of Zootechny and Food Engineering (FZEA) in Pirassununga, SP.

The study’s other author, Arlindo Saran Netto, received a Post-Doctoral Fellowship from FAPESP and during his research in 2010 was hired as dean of the FZEA. According to Zanetti, the study is groundbreaking in that it brings the areas of zootechnics and animal nutrition together with a study on the effects of the product on human health. The study was carried out in partnership with researchers from the Paulista Agency of Agribusiness Technology (APTA) in Riberão Preto (SP).

“Many studies have been done on the possibility of changing animal feed with the intention of improving, in theory, the quality of products for human consumption. But our work went a step further in comparing the effect of enriching milk with a product and seeing if it really is better for human health,” Zanetti told Agência FAPESP.

Known to have antioxidant effects, selenium is an important mineral for combatting free radicals. According to Zanetti studies performed at the USP School of Pharmaceutical Sciences proved that the Brazilian diet is deficient in the mineral—with the exception of the North, where many people eat Brazil nuts, rich in selenium. Vitamin E was combined with the mineral because of its complementary antioxidant effects.

“Cardiovascular diseases are considered to be the main problems to public health and milk, which is a food rich in many nutrients, is frequently associated with them because of their high percentage of saturated fatty acids and their level of cholesterol,” he pointed out.

Sunflower oil was used as the source of fat for enriching the feed in bringing together its actions to the antioxidant effects of selenium and vitamin E in the physicochemical composition of the milk. “The oil changes the profile of the fatty acids in the milk, improving the product nutritionally. It also optimizes the effect of the antioxidants,” explained Zanetti. This change in profile diminishes the shelf life of the milk, but the antioxidants reverse this effect.

In the experiment, 24 cows were used in four different types of treatment. The control group received normal feed, the second group received feed with 2.5 milligrams of selenium and 1000 UI of vitamin E per day. The third group received feed with 3% added sunflower oil and the fourth ate feed with the sunflower oil, 2.5 mg of selenium and 1000 UI of vitamin E per day.

“We measured the consumption and milk production of the animals daily and the milk samples were collected weekly and analyzed for fat, protein, lactose, calcium, phosphorus, total solids and somatic cells. The milk obtained from each treatment was pasteurized and stored in its respective container. A skim milk treatment was also included,” he explained.

More selenium

The milk was given to children from the first to fourth grades that study full time at the Escola Professora Stela Stefanini Bacci in Casa Branca, SP. The one hundred students recruited for the study had previously undergone clinical and laboratorial tests and were identified as healthy.

“The 7-10 year olds were measured and underwent biochemical blood testing in clinical analysis labs. The blood samples were collected by a medical team,” said Zanetti.

The findings were ample. According to the scientists, the benefits of the enriched feed were first observed in the animals. “The inclusion of sunflower oil together with organic selenium and vitamin E benefited the health of the mammary glands in the cows, resulting in less subclinical mastitis, more milk production, lower ingestion of dry material and less fat in the milk,” he affirmed.

In addition, supplementing the cows’ feed with selenium and vitamin E was efficient in improving selenium and vitamin E concentration in the whey and significantly increased concentration of the two antioxidants in the milk produced by the animals. The antioxidants, in turn, increased the shelf life of the milk.

“Adding the sunflower oil to the cows’ diets, on the other hand, significantly changed the profile of the fatty acids in their milk. One of the most notable effects was that it increased the level of conjugated linoleic acid (CLA) in the product,” he said.

As for the children, those that drank the milk from the cows supplemented with selenium and vitamin E had higher levels of antioxidants in their plasma. “By adding vitamin E to the feed, we found a 33% increase in the serum level of vitamin E in the children’s blood,” the FZEA-USP professor explained.

The children that drank milk from cows that received only sunflower oil added to their feed had even higher vitamin E levels: 45%. “This happened because the oil optimizes the absorption of the vitamin E,” he said.  

Meanwhile, the children that drank skim milk had a drop in vitamin E levels as compared to the control group. “The children that drank the cow milk supplemented with only selenium and vitamin E had blood selenium levels 160% higher than the children in the control group. In the children that drank cow milk supplemented with sunflower oil, the selenium levels showed little variation, increasing just 4%. But in those that drank skim milk, the selenium levels fell by 20%,” he affirmed.

The conclusion is that milk produced by cows whose feed had been enriched with selenium, vitamin E and sunflower oil increased the antioxidant and CLA levels in the children, which, according to Zanetti, offers health benefits.

“Unfortunately, we don’t have enriched milk in Brazil. It would be beneficial if it were produced and placed on the market—especially because we know that the diet of our population is selenium deficient. Plus, the enrichment process isn’t expensive,” he affirmed.