Why yes, they were done.
The problem is, they were memory-holed, because they didn't prove what they set out to prove.
Nina Teicholtz (author of the outstanding book The Big Fat Surprise) has a great article on the whole debacle. Infuriating, but great.
This is the original link: https://unsettledscience.substack.com/p/major-nih-nutrition-trials-on-diet
Here's an archive link, in case you can't see it: https://archive.vn/Erjxn
This is the standard advice:
"A healthy diet is one high in fruits, vegetables, whole grains, beans and legumes, fish and seafood, nuts, and seeds, while lower in sugar, red and processed meats, and ultra-processed foods. Additionally, she and most experts recommend low-fat dairy products over the full-fat variety and seed oils over butter."
This is The Diet, endorsed by nearly all experts and health organizations. Harvard agrees; Tufts agrees; Stanford agrees; the Mayo Clinic agrees; the American Heart Association, the American Academy of Pediatrics, the American Cancer Society, and yes, the U.S. Dietary Guidelines of Americans—our nation’s top nutrition policy--all agree. Everyone agrees.
But the problem is similar to what happened in Covid. Dissenting viewpoints were crushed, anyone who dared to challenge them lost their funding and/or job.
Enforcement has long been strict within the field of nutrition science. Since the early 1960s, the central idea that saturated fat and cholesterol cause heart disease, called the “diet-heart hypothesis,” was adopted by leading nutrition experts of the day, including those at the American Heart Association and NIH. This hypothesis meant cutting back on meat, full-fat dairy, eggs, and butter, which necessitated a shift to seed oils, fruits, vegetables, and grains—the eventual components of The Diet.
Critics who spoke out against the diet-heart hypothesis saw their careers virtually ruined. For instance, when the once-prominent NIH-funded scientist George Mann from Vanderbilt University, a director of the famous Framingham Heart Study, went public with research findings contrary to the hypothesis in the 1970s, he found his NIH research grant canceled. Mann had spent two years collecting food-consumption data from 1,000 Framingham subjects, with the conclusion that when it came to saturated fats and coronary heart disease, “No relationship found.”
The studies were done - very expensive, multi-million dollar studies - but the results were not satisfactory, so they were not publicized.
Los Angeles Veteran’s Trial
Summary: A diet that replaced saturated fat with vegetable oils successfully lowered cases of heart disease yet did not reduce total mortality. The men on the seed oil diet died at higher rates of cancer.
Multiple Risk Factor Intervention Trial Research Group (MRFIT) Trial
Summary: A large and long-term nutrition study found that a diet low in saturated fat and cholesterol increased rates of death and lung cancer in men compared to controls.
Minnesota Coronary Survey
Summary: The largest-ever test of the “diet-heart hypothesis” found that saturated fats have no effect on heart disease, cardiovascular mortality, or total mortality. In addition, researchers later found that the more the subjects lowered their cholesterol, the higher their risk of death.
Nina Teicholtz summarizes:
How and why these important research findings have been so long ignored is a complex story, but the anecdotes above, about George Mann and Ivan Frantz, provide a glimpse into the long-time groupthink that has dominated this field of science.
Due to this lamentable history, restrictions on saturated fat remain; the low-fat diet is still enshrined in USDA feeding assistance programs, including school lunches; and the guidelines still recommend diets “lower in cholesterol,” despite all the rigorous, ignored evidence to the contrary.