A Conversation with Dave Feldman, with References

How'd I do THIS time... ?

I met Dave Feldman at his first low carb conference where he showed anyone who’d listen the data from his initial personal experiments. What he’s achieved since then has been remarkable. He’s posted information on his website Cholesterol Code, built Own Your Labs to make blood tests more affordable, assembled a group of researchers (published work), crowd funded major research projects in part through the Collaborative Science Foundation and three CoSci conferences, and co-written a documentary film The Cholesterol Code (highly recommended!). I’ve been a fan and a supporter. His latest effort is the Feldman Protocol podcast.

Dave and I, with some other guy…

Episode #34 (Spotify & Apple) was just released. It’s also on YouTube (for now)

I was a guest on episode #10 but, as Dave explains, that episode is no longer on YouTube (it is still available on Spotify and Apple). We believe a particular topic discussed in that episode triggered its suppression on YouTube, affecting not only that episode but apparently the channel more broadly. Dave ultimately chose to delete the episode—a decision I supported—after which the channel’s normal growth resumed. We intentionally avoided that topic this time. We’ll see if that was enough.

We covered a lot of ground—literally and figuratively! Over three and a half hours we discussed ruminant digestion, protein quality, land use, human-edible feed conversion, metabolic health, animal-source foods, and the role of livestock in sustainable food systems. Segments will be released on his channel.

Ideas We Discussed

• Ruminants primarily convert resources humans cannot eat into foods rich in indispensable amino acids and other essential nutrients in their most bioavailable forms

• Much of the world’s agricultural land is unsuitable for crop production but suitable for grazing.

• Livestock and plant agriculture are necessarily integrated.

• Protein quality matters, not just protein quantity.

• Animal-source foods play important roles in meeting micronutrient requirements.

• Evaluating food systems requires considering both human health and environmental outcomes.

Many of these claims run counter to conventional narratives about livestock, protein, and human nutrition. During the conversation I mentioned a large number of studies, books, databases, and reports. Rather than leave listeners searching for them individually, I’ve assembled them here in roughly the order they arose in the discussion. If I’ve missed something, please let me know and I’ll add it.

Background references

Bonus!

The Tyranny of Crude Protein may be of interest.

I recently gave a presentation via Zoom - Protein on Paper vs. Protein for People (link to a pdf of the PowerPoint slides w/ notes). It was intentionally “diet agnostic” for an audience that’s heavily influenced by the “plant-based” message.

The references below are organized roughly in the order they arose during the conversation.

Ruminants

Church, D. C. 1993. The Ruminant Animal: Digestive Physiology and Nutrition. (textbook)

Krehbiel, C. R. 2014. INVITED REVIEW: Applied nutrition of ruminants: Fermentation and digestive physiology1. The Professional Animal Scientist 30(2):129–139. https://www.sciencedirect.com/science/article/pii/S1080744615301005

Ruminant microbiome and digestion - Cammack, K. M., K. J. Austin, W. R. Lamberson, G. C. Conant, and H. C. Cunningham. 2018. RUMINANT NUTRITION SYMPOSIUM: Tiny but mighty: the role of the rumen microbes in livestock production. J. Anim. Sci. 96(2):752–770. https://doi.org/10.1093/jas/skx053

Beef is a net protein contributor - Baber, J. R., J. E. Sawyer, and T. A. Wickersham. 2018. Estimation of human-edible protein conversion efficiency, net protein contribution, and enteric methane production from beef production in the United States. Translational Animal Science 2(4):439–450. http://dx.doi.org/10.1093/tas/txy086

Nutrients / nutrition

Amber O’Hearn’s 2019 presentation, Measures of Dietary Quality

Indispensable amino acids - Berg, E. P. and H. H. Stein. 2021. A Salute to PVT TIM HiLL: Indispensable Amino Acids and Global Human Health. Meat and Muscle Biology 5(3). https://dx.doi.org/10.22175/mmb.12925

Food supply statistics available from FAOStat https://www.fao.org/faostat/en/#home

Soybean database - https://www.cropcomposition.org

Cooking cereals changes DIAAS value - Han, F., F. Han, Y. Wang, L. Fan, G. Song, X. Chen, P. Jiang, H. Miao, and Y. Han. 2019. Digestible indispensable amino acid scores of nine cooked cereal grains. British Journal of Nutrition 121(1):30–41. https://dx.doi.org/10.1017/s0007114518003033

“A lot to digest” – Berg and Stein. 2021. ibid

National Live Stock and Meat Board. 1933. Ten Lessons on Meat: For use in the classroom. https://babel.hathitrust.org/cgi/pt?id=coo.31924003579491&seq=76

Land use

FAOSTAT Land Use Database - https://www.fao.org/faostat/en/

USDA NRCS Land Capability Classification - https://efotg.sc.egov.usda.gov/references/Delete/2015-11-14/123_land_capability_10232014.pdf

Integrated Crop Livestock Systems

de Moraes, A., et al. 2014. Integrated crop–livestock systems in the Brazilian subtropics. European Journal of Agronomy 57:4–9. https://doi.org/10.1016/j.eja.2013.10.004

Bell, L. W. and A. D. Moore. 2012. Integrated crop–livestock systems in Australian agriculture: Trends, drivers and implications. Agricultural Systems 111:1–12. https://doi.org/10.1016/j.agsy.2012.04.003

Franzluebbers, A. J. 2007. Integrated Crop–Livestock Systems in the Southeastern USA. Agron. J. 99(2):361–372. https://dx.doi.org/10.2134/agronj2006.0076

Freitas, C. M., et al. 2023. System fertilization in the pasture phase enhances productivity in integrated crop–livestock systems. The Journal of Agricultural Science:1–8. https://dx.doi.org/10.1017/s0021859623000606

Feed / Food

Edible portion of NPP & HANPP estimates derived from - Haberl, H., et al. 2007. Quantifying and mapping the human appropriation of net primary production in earth’s terrestrial ecosystems. Proceedings of the National Academy of Sciences 104(31):12942–12947. https://dx.doi.org/10.1073/pnas.0704243104

96% of the feed consumed by all domestic ruminants is not human edible - Mottet, A., et al. 2018. Review: Domestic herbivores and food security: current contribution, trends and challenges for a sustainable development. animal 12(s2):s188–s198. https://dx.doi.org/10.1017/s1751731118002215

86% of the feed consumed by all domestic livestock is not human edible - Mottet, A., et al. 2017. Livestock: On our plates or eating at our table? A new analysis of the feed/food debate. Global Food Security 14:1–8. https://doi.org/10.1016/j.gfs.2017.01.001

FAO. 2010. Draught Animal Power: An overview. FAO Agricultural Engineering Branch, Rome, Italy. https://www.fao.org/fileadmin/user_upload/ags/publications/draugth_ap_overview.pdf

Draft and Manure

Mota-Rojas, D., et al. 2021. The Use of Draught Animals in Rural Labour. Animals 11(9):2683. https://dx.doi.org/10.3390/ani11092683

Rayne, N. and L. Aula. 2020. Livestock Manure and the Impacts on Soil Health: A Review. Soil Systems 4(4):64. https://www.mdpi.com/2571-8789/4/4/64

Leip, A., et al. 2019. The value of manure - Manure as co-product in life cycle assessment. J. Environ. Manage. 241:293–304. https://www.sciencedirect.com/science/article/pii/S0301479719303627?via%3Dihub

Household air pollution - https://www.who.int/news-room/fact-sheets/detail/household-air-pollution-and-health

Cooking with dung - https://energypedia.info/wiki/Cooking_with_Dung

An egg a day / Too little ASF

Iannotti, L. L., et al. 2017a. Eggs in early complementary feeding and child growth: a randomized controlled trial. Pediatrics 140(1). https://doi.org/10.1542/peds.2016-3459

Iannotti, L. L., et al. 2017b. Eggs early in complementary feeding increase choline pathway biomarkers and DHA: a randomized controlled trial in Ecuador. The American journal of clinical nutrition 106(6):1482–1489. https://doi.org/10.3945/ajcn.117.160515

Iannotti, L., et al. 2021. Livestock-derived foods and sustainable healthy diets. https://www.unnutrition.org/wp-content/uploads/Livestock-Paper-EN_WEB.pdf

Leroy, F., et al. 2023. The role of meat in the human diet: evolutionary aspects and nutritional value. Animal Frontiers 13(2):11–18. https://doi.org/10.1093/af/vfac093

Berg, E. P. 2019. Foods of animal origin: a prescription for global health. Animal Frontiers 9(4):3–4. https://doi.org/10.1093/af/vfz036

Blue zones

Blue Zones - https://www.aleph2020.org/search-results?tx_kesearch_pi1%5Bsword%5D=blue%20zone

Thresholds

At least 50% of dietary protein should come from animal source foods - Vieux, F., et al. 2022. Approximately Half of Total Protein Intake by Adults Must be Animal-Based to Meet Nonprotein, Nutrient-Based Recommendations, With Variations Due to Age and Sex. The Journal of Nutrition 152(11):2514–2525. https://dx.doi.org/10.1093/jn/nxac150

<30% of calories from animal source foods, multiple micronutrient deficiencies emerge - Nordhagen, S., et al. 2020. GAIN Discussion Paper Series 5 - The role of animal-source foods in healthy, sustainable, and equitable food systems. https://doi.org/10.36072/dp.5

60-80% of dietary protein from animal source foods - Ridoutt, B., et al. 2025. Protein Source and Micronutrient Adequacy in Australian Adult Diets with Higher Diet Quality Score and Lower Environmental Impacts. Dietetics 4(35). https://dx.doi.org/10.3390/dietetics4030035

Decreasing protein digestibility with increasing plant source - Moughan, P. J. 2021. Population protein intakes and food sustainability indices: The metrics matter. Global Food Security 29:100548. https://dx.doi.org/10.1016/j.gfs.2021.100548

Oysters, Beans & Tortillas

Zinc, Oysters, black beans & corn tortillas - Solomons, N., et al. 1979. Studies on the bioavailability of zinc in man. 2. Absorption of zinc from organic and inorganic sources. Journal of Laboratory and Clinical Medicine 94(2):335–343. https://www.cabidigitallibrary.org/doi/full/10.5555/19791494841

DIAAS

FAO/WHO. 2013. Dietary protein quality evaluation in human nutrition. Report of an FAO Expert Consultation, 31 March–2 April, 2011, Auckland, New Zealand. FAO food and nutrition paper 92. https://www.fao.org/ag/humannutrition/35978-02317b979a686a57aa4593304ffc17f06.pdf

Bailey, H. M. and H. H. Stein. 2019. Can the digestible indispensable amino acid score methodology decrease protein malnutrition. Animal Frontiers 9(4):18–23. https://doi.org/10.1093/af/vfz038

Moughan, P. J. and W. X. J. Lim. 2024. Digestible indispensable amino acid score (DIAAS): 10 years on. Frontiers in Nutrition 11. https://dx.doi.org/10.3389/fnut.2024.1389719

“Equivalents”

Ounce equivalents - Park, S., et al. 2021. Metabolic Evaluation of the Dietary Guidelines’ Ounce Equivalents of Protein Food Sources in Young Adults: A Randomized Controlled Trial. The Journal of Nutrition 151(5):1190–1196. https://dx.doi.org/10.1093/jn/nxaa401

Odds & Ends

Adele’s dissertation - Hite, A. H. 2019. A Material-Discursive Exploration of “Healthy Food” and the Dietary Guidelines for Americans. https://repository.lib.ncsu.edu/server/api/core/bitstreams/28491ba6-8ae5-4f63-82ab-1ef96d32bf50/content

Working Group member David Klurfeld, the evidence supporting the Group 2A classification of red meat was weaker than many public interpretations suggested - Klurfeld, D. M. 2018. What is the role of meat in a healthy diet? Animal Frontiers 8(3):5–10. https://dx.doi.org/10.1093/af/vfy009

Animal-Sourced Foods in Ethical, Sustainable, and Healthy Diets: A dynamic white paper on the role of livestock farming in global agrifood systems and diets, ALEPH2020.org

National Cattlemen’s Beef Association (NCBA) - https://www.ncba.org/

• Listing of state affiliates - https://www.ncba.org/about/affiliates-industry-organizations

Cooperative Extension - https://www.nifa.usda.gov/about-nifa/what-we-do/extension/cooperative-extension-history

• Find extension in your state - https://extension.org/find-cooperative-extension-in-your-state/

Land-grant Universities - https://www.nifa.usda.gov/grants/land-grant-university-website-directory