This episode examines what we actually know (and importantly, what we do not know) about diet in relation to gallstones and gallbladder conditions. Much of the public-facing guidance around gallstones focuses on "avoiding fatty foods", yet Dr. Angela Madden explains that this long-standing practice sits on surprisingly weak direct evidence, particularly when judged against the standards typically expected for clinical dietary recommendations.

A central theme is the need to separate two distinct questions: dietary factors that influence the risk of developing gallstones (prevention), versus dietary strategies intended to reduce symptoms or complications once gallstones exist (management). While the prevention literature suggests plausible, consistent associations with overall diet quality and lifestyle factors, the specific question of prescribing a low-fat diet to manage symptomatic gallstones lacks robust randomized trial evidence.

Dr Angela Madden is a clinical researcher in nutrition and dietetics at the University of Hertfordshire, where she established and led the nutrition and dietetics subject group and now focuses her research on improving nutritional assessment, dietary interventions, and patient-centred outcomes in clinical and public health settings.

• [02:09] Discussion with Dr. Angela Madden begins
• [06:53] Understanding the gallbladder
• [08:08] Gallbladder disorders and their prevalence
• [13:42] Risk factors and pathophysiology
• [22:15] Dietary factors and gallstone formation
• [27:20] Exploring dietary fat and gallstones
• [34:09] Broader dietary considerations
• [45:44] Practical dietary recommendations

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• Dr. Madden's univeristy page
• Cochrane Review: Madden et al., 2024 – Modified dietary fat intake for treatment of gallstone disease in people of any age
• Related episode: 513: Kidney Stones & Diet – Deepa Kariyawasam, RD

In this episode, Danny answers questions submitted by Premium subscribers.

1. [00:05:13] Is eating too early (relative to chronotype) metabolically problematic?
2. [00:16:55] Can plant-based diets reverse cardiovascular disease?
3. [00:32:54] Are multivitamins useful insurance, or a waste with a good diet?
4. [00:44:56] Does coevolution with foods determine human compatibility and benefit?
5. [00:56:25] How should consumers choose supplement formulations and brands?
6. [01:04:46] Folate vs folic acid: differences and best choice for women of childbearing age?
7. [01:12:37] How reliable is omega-3 content in farmed salmon, especially imported frozen salmon?
8. [01:19:18] How accurate are food labels for metabolizable energy and absorption, especially across processing levels?
9. [01:23:58] Protein needs in breastfeeding and general rehabilitation (non-sport injury)?

To listen to the full episode, subscribe to Sigma Nutrition Premium.

• Go to episode page (with full resource list)
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• Resources for this episode:
  • Eckel et al., 2015 – Morning Circadian Misalignment during Short Sleep Duration Impacts Insulin Sensitivity
  • Stothard et al., 2020 – Early Morning Food Intake as a Risk Factor for Metabolic Dysregulation
  • Ep. #470: Melatonin, Meal Timing & Glucose Tolerance
  • Ep. #579: Is Your Chronotype Hard-Wired or Modifiable?
  • Article: A Plant Based Diet Reverses Heart Disease: True or False?

"The more we learn about the world, and the deeper our learning, the more conscious, specific, and articulate will be our knowledge of what we do not know, our knowledge of our ignorance. For this, indeed, is the main source of our ignorance — the fact that our knowledge can be only finite, while our ignorance must necessarily be infinite." – Karl Popper

To mark Sigma Nutrition's milestone 600th episode (and 12-year anniversary), Danny and Alan examine several areas in which their views have changed, softened, strengthened, or remained stable over the lifespan of the podcast.

The discussion is therefore not only about nutrition itself, but also about the process of scientific reasoning: how positions are formed, what type of evidence can shift them, and why changing one's mind is often a sign of better thinking rather than inconsistency.

The episode therefore serves as both a review of several specific nutrition controversies and a lesson in scientific epistemology. They discuss topics such as red meat, protein, dietary cholesterol, omega-3s, flavonoids, and sodium.

• [11:04] Time-restricted eating
• [19:32] Protein intake, quality & dosing
• [35:04] Cocoa flavanols and cognition
• [51:38] Unprocessed red meat
• [01:05:23] Omega-3 supplementation
• [01:23:10] Dietary cholesterol
• [01:44:41] Sodium J-curve myth
• [01:53:41] Energy balance model

Links

• Go to episode page (with study links & resources)
• Join the Sigma email newsletter for free
• Subscribe to Sigma Nutrition Premium
• Enroll in the next cohort of our Applied Nutrition Literacy course