Browse evidence-based analysis of health-related claims and assertions
Heating flaxseeds before pressing them and pressing them twice makes more oil that lasts longer — because the heat helps release natural antioxidants that work together to protect the oil.
Descriptive
When you add both vitamin E and plant sterols to flaxseed oil together, they work better than either one alone to keep the oil from going rancid — this combo could help make healthier oils that last longer.
Plant sterols — natural compounds in flaxseed — help keep the oil from going bad by stopping the chain reaction that causes rancidity and calming down unstable molecules in the oil.
Mechanistic
Adding too much of one type of vitamin E (α-tocopherol) to flaxseed oil can make it go bad faster when it's cool, but helps protect it when it's warm — because another type of vitamin E (γ-tocopherol) lasts longer and keeps working.
In flaxseed oil, a natural compound called γ-tocopherol stops oil from going bad by mopping up harmful molecules, and other natural compounds in the oil help keep γ-tocopherol working longer.
Industrial refining processes of seed oils—including degumming, bleaching, and deodorization at high temperatures—generate toxic lipid oxidation byproducts such as reactive aldehydes and trans fats.
Assertion
Human metabolic systems lack evolutionary adaptation to high dietary intake of polyunsaturated fatty acids derived from industrial seed oils.
Thermal exposure during cooking degrades polyphenolic antioxidants in extra virgin olive oil, eliminating their bioactive health effects.
Isolation of lipids from whole foods removes endogenous antioxidants and structural matrices, increasing susceptibility to oxidative degradation.
The historical incidence of acute myocardial infarction in the United States was negligible prior to the widespread introduction of industrial seed oils in the early 20th century.
Quantitative
Human evolutionary physiology is adapted to metabolize and utilize animal-derived saturated and monounsaturated fats as primary dietary lipids.
Extra virgin olive oil produces higher levels of polar compounds and oxidative byproducts than saturated animal fats and coconut oil when subjected to prolonged heating.
Oils with polyunsaturated fatty acid content exceeding 10% are susceptible to thermal oxidation during cooking, generating cytotoxic aldehydes and lipid peroxides.
Women in this study were more likely than men to have high BMI and large waist size, and both of these were linked to higher heart risk markers—even if they didn’t have diabetes or high blood pressure.
Correlational
Measuring your waist compared to your height isn’t any better than just using your BMI or waist size to guess your heart risk—all three are about equally useful in this group.
Measuring your waist compared to your height, your weight relative to your height, or just your waist size can all tell you something about your risk for heart problems—even if you don’t have diabetes or high blood pressure.
Belly fat naturally makes less estrogen than fat under the skin, no matter if you're a man or a woman.
Insulin by itself doesn’t change estrogen production in fat, but when it’s with cortisol, it makes the difference between men and women disappear.
After menopause, belly fat becomes more responsive to stress hormones by making more estrogen than before menopause.
In belly fat, cortisol makes both men and women’s fat cells make more estrogen, but it boosts it way more in men than in women.
In women, a stress hormone called cortisol makes fat tissue produce more estrogen, but in men, it does the opposite—this might help explain why women store more fat under the skin than men.
Unlike belly fat, gaining or losing fat around the hips didn’t seem to affect how likely women were to die or have heart disease over six years.
Women who started at a normal weight or had smoked in the past were at the highest risk if their waist got bigger over six years.
Women who gained belly fat over six years were more likely to die or have heart problems later, even if they weren't overweight to begin with.