Does SATURATED FAT cause HEART ATTACKS? (part 1)

Does reducing saturated fat actually prevent heart attacks? For decades, saturated fat from foods like butter, red meat, cheese, coconut oil, and full-fat dairy has been treated as something to reduce. But the new USDA/HHS dietary guidelines and the inverted food pyramid have made the message a lot less clear. In this episode, Calvin and John look closely at two 2025 meta analyses of randomized controlled trials: Yamada 2025 and Steen 2025. One says reducing saturated fat “cannot be recommended”. The other says there may be a benefit, but mostly depending on your cardiovascular risk and what you replace saturated fat with. We go deep into the studies, recreate some of the charts, check the reported metrics, look at the forest plots, compare odds ratios and risk ratios, and dig into where the conclusions seem strong, weak, or a little too confident. Hopefully, there’s also something useful here about how to think through studies, evidence, and nutrition claims when the answer is not as clean as it first seems. This is the first of a series of videos on the subject. Papers: Steen et al. 2025 https://pubmed.ncbi.nlm.nih.gov/41397... Yamada et al. 2025 https://pubmed.ncbi.nlm.nih.gov/40416... #SaturatedFat #HeartDisease #NutritionScience #DietaryGuidelines #MetaAnalysis 0:00 Intro: Does cutting saturated fat actually prevent heart attacks? 4:19 What saturated fat is, and what question we're asking 8:54 Yamada 2025 and Steen 2025: the main conclusions 15:42 Yamada details 20:17 Yamada: the heart attack result is right on the edge 31:22 Yamada: MI vs any coronary event count problems 40:19 Steen: more nuanced, more uncertain, more quantitative 44:24 Steen: The non-fatal heart attack signal 50:28 Steen: Important absolute risk reduction 58:51 Overall Comparisons of Yamada and Steen 1:00:40 Combing the results; an endpoint-gradient pattern? 1:04:44 Why all-cause mortality can dilute the signal. Traffic accidents. 1:09:54 Wrap up: Why the inconsistency?