Browse evidence-based analysis of health-related claims and assertions
When you heat olive oil really hot, the healthy unsaturated fats break down much faster than the saturated ones—oils with more unsaturated fats lose them the most, making the oil less healthy.
Quantitative
When olive oil gets super hot (200°C), it starts forming gummy, sticky molecules called dimers—some oils make way more than others, especially blends high in Arbequina, while Picual makes the least.
In pig milk cells, the GPR40 receptor is more important than GPR120 for helping oleic acid make milk fat.
Descriptive
When you heat olive oil really hot (200°C), the good antioxidants called tocopherols disappear—some oils lose them completely, while others like Picual and Cornicabra keep a little bit left.
Baby pigs whose moms ate more oleic acid got more protective substances like antibodies and antioxidants through the milk, which may help them stay healthier after birth.
When scientists blocked one specific receptor (GPR40) in pig milk cells, the cells made about 38% less milk fat from oleic acid — blocking the other receptor (GPR120) had a smaller effect.
In pig milk-making cells, oleic acid turns on certain fat-handling proteins and helps make more milk fat, and this happens mostly through two specific cell receptors called GPR40 and GPR120.
Mechanistic
When mother pigs eat more oleic acid (a healthy fat), their milk becomes fattier and their baby pigs grow bigger by the time they're weaned.
The blue dye methylene blue cut the amount of a harmful chemical (hydrogen peroxide) in heart and blood vessel fat by about half when tested in the lab.
The fat directly on the heart makes more harmful chemicals than the fat around blood vessels, and this matches with it having more of the enzyme MAO-A.
When the fat tissue was given serotonin (a chemical the body uses in mood and digestion), it made over twice as many harmful molecules — but adding methylene blue cut that increase in half, showing the enzyme MAO-A is involved.
Correlational
In the fat around the heart and blood vessels of heart failure patients, a specific enzyme called MAO-A is much more common and makes more harmful chemicals than its cousin MAO-B.
Even with different fat diets and different amounts of vitamin E, the rats' testicles and sperm storage areas looked normal — vitamin E didn’t change their appearance.
Giving rats 40 IU of vitamin E per kg of food stopped almost all fat damage — giving them even more (100 IU) didn’t help any further.
When fat tissue around the heart and blood vessels was soaked in a blue dye called methylene blue for a day in the lab, it made less of a harmful enzyme and produced fewer damaging chemicals, which might help explain how the dye could protect cells.
Even when rats ate a lot more of the kind of fat that's more likely to go bad (polyunsaturated), their fat damage didn't go up as long as they got enough vitamin E.
When rats didn't get any vitamin E in their food, their bodies showed more signs of fat damage, no matter what kind of fats they ate.
When rats ate diets with different types of fats, giving them a specific amount of vitamin E (40 or 100 IU per kg of food) greatly lowered signs of fat damage in their bodies, and that amount was enough to stop most of the damage.
Mice with a human gene variant called ApoE4 have less of certain fat molecules in their brains than normal mice, no matter what they eat.
The way olive oil is made and stored in different places might help it last longer, but we can't say for sure which part makes the difference.
Scientists can tell if olive oil is going bad by shining light on it and watching how the color changes — darker spots mean the good stuff is breaking down, and brighter spots mean bad stuff is forming.
Olive oil from Al-Jouf stays fresher longer than olive oil from Pakistan when left out at room temperature, based on how quickly it breaks down.
The belly fat in mice makes a lot of a heat-boosting chemical when it’s cold—but when the mice are inflamed or have this bacteria, that fat stops making it, while other fat types don’t change as much.
When mice were made sick with a bacterial toxin, they got colder in the cold—but so did mice that were fed a specific gut bacteria, even though they ate the same amount and didn’t gain weight.