Blood levels of saturated fat have been linked with increased risk for dementia, but how do those fats get there in the first place? 34 “It is commonly believed that circulating fatty acids reflect dietary intake, but the associations are weak, especially for SFA (saturated fatty acids),” wrote researchers from Ohio State University in PLOS ONE, seeking to answer this very question.
35 They found that two of the saturated fats linked with dementia, stearic and politic acids, did not become elevated in the blood even when their subjects consumed them in amounts as high as 84 grams per day—the equivalent of nearly eleven tablespoons of butter! On the other hand, the highest circulating saturated fats were measured after the subjects consumed a high-carbohydrate diet, while eating fewer carbohydrates led to lower circulating levels.
As it turns out, most of the body’s circulating levels of saturated fats originate in the liver, where they are produced in response to carbohydrates—a process called lip genesis, or fat creation. Other studies have demonstrated similar results, proving that our bodies are dynamic chemistry labs that don’t always follow simple logic—a fact often used to sell food products, pharmaceutical drugs, or general misinformation
When it comes to the impact that saturated fat has on the brain, finding truthful answers can be tricky. Close inspection of many animal studies nearly universally reveals that what is reported as a “high-fat diet” for the animals is, in reality, a toxic slurry of sugar, lard, and soybean oil. ‡ This might trace back to a basic labeling oversight—lab suppliers of rat chow often label diets meant to mimic the Standard American Diet as simply “high fat