The Proof with Simon Hill
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The Diet That Lowers Cholesterol Like a Statin | Dr Andrea Glenn

May 4, 2026

AI Summary

5 min read

When Dr. Andrea Glenn and her colleagues at Harvard published a study on protein ratios last year, they expected it to generate conversation. Instead, it was largely ignored by the loudest voices in the nutrition space—the same ones who spend hours telling people to eat more protein. The finding? A higher ratio of plant to animal protein was linked to lower cardiovascular disease risk, and people who combined that with higher total protein intake did even better. The study quietly challenged both the high-animal-protein crowd and the low-protein plant-based crowd at the same time.

The Protein Ratio Study That Nobody Talked About

The study analyzed data from roughly 200,000 healthcare professionals across three large Harvard cohorts, following them for up to 30 years with dietary assessments every four years. The key variable was the plant-to-animal protein ratio—essentially, how much of your protein comes from plants versus animals. For total cardiovascular disease and stroke, the benefits plateaued at a ratio of about 0.5, meaning one gram of plant protein for every two grams of animal protein. For coronary heart disease specifically, the benefits continued to improve closer to a one-to-one ratio.

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What you'll learn

  • 1 (00:50) **The Plant-to-Animal Protein Ratio Study** - Dr. Glenn explains the rationale and design of a major study looking at how the balance of protein sources affects cardiovascular disease.
  • 2 (05:47) **Protein Density: The "Joint Effects" Finding** - The study explored whether the total amount of protein (density) matters alongside the source ratio.
  • 3 (08:56) **Why This Study Challenges Both High-Protein and Low-Protein Camps** - The findings suggest that the source of protein is critical, moving beyond the debate over total protein quantity.
  • 4 (10:26) **Defending Nutritional Epidemiology** - Dr. Glenn explains how large observational studies work, their purpose, and their limitations in the face of online criticism.
  • 5 (16:17) **How Epidemiology Fits in the Totality of Evidence** - Dr. Glenn explains how to triangulate data from different study types to form strong dietary recommendations.
  • 6 (21:36) **Addressing the "Healthy User Bias" Critique** - A deep dive into how scientists account for the fact that people who eat well also tend to have other healthy habits.
  • 7 (24:24) **The Power of Sensitivity Analyses** - A detailed look at the specific tests used to strengthen the findings of the protein study.

+ Full timestamped outline available in the app

Show Notes

Plant-based nutrition has rarely been more contested. Seed oils are vilified, butter is celebrated, protein is treated as a pure quantity question, and nutrition epidemiology is routinely dismissed by people who have never read one of its papers. In this episode, I sit down with Dr Andrea Glenn, an Assistant Professor at NYU and Visiting Scientist at the Harvard T.H. Chan School of Public Health, to look at what the strongest evidence actually shows.

We cover the recent plant-versus-animal protein data from the Nurses' Health Studies and Health Professionals Follow-up Study, the Portfolio Diet, the new CHEAP trial, the JAMA Internal Medicine butter and plant oil paper, and the new 2026 AHA dietary guidance.

What we cover:

  • The plant-to-animal protein ratio and its association with cardiovascular and coronary heart disease risk
  • The Portfolio Diet, what it contains, and how its LDL-lowering effects compare to a low-dose statin
  • Butter, beef tallow, tropical oils, and what the latest mortality data show
  • Why "low-carb" is not one diet, and why food sources matter as much as the macronutrient breakdown
  • A grounded defence of nutrition epidemiology and the role of food frequency questionnaires
  • Practical takeaways for how to eat in line with the new AHA guidance

This is the conversation I wanted to have for anyone tired of nutrition by hashtag. If it lands, a quick rating or review on Apple Podcasts or Spotify makes a real difference.

To follow more of Dr Andrea Glenn's work, find her on Instagram at instagram.com/andrea.glenn.rd, on X at x.com/andreaglennrd, and on LinkedIn at linkedin.com/in/andrea-glennrd.

  • Intro (00:00)
  • Plant vs Animal Protein Ratio and Heart Disease (01:17)
  • Does Total Protein Amount Also Affect CVD Risk? (05:33)
  • Why Nutrition Epidemiology Critics Often Get It Wrong (11:00)
  • Where Epidemiology Fits in the Evidence Hierarchy (17:28)
  • Sensitivity Analyses: How Scientists Test Their Results (22:16)
  • What It's Like Doing Science at Harvard (28:55)
  • The Portfolio Diet: Origins and the Science Behind It (32:21)
  • The CHEAP Trial: Testing Portfolio Diet Long-Term (41:03)
  • Portfolio Diet in Cohort Studies: What the Data Shows (50:24)
  • Unsaturated Fats: Are They Inherently Heart-Protective? (56:16)
  • Phytosterol Supplements: LDL Benefits vs Safety Questions (01:00:06)
  • Butter vs Plant Oils: What Mortality Data Actually Shows (01:06:57)
  • Plant vs Animal MUFAs and Type 2 Diabetes Risk (01:12:11)
  • Low-Carb Diet Quality and Diabetes Risk: New Data (01:15:37)
  • 2026 AHA Dietary Guidelines: Key Differences Explained (01:20:23
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