ADG Review Evidence Submission
Please sign the petition requesting that the Australian Dietary Guidelines recommendations be reviewed and amended in light of new evidence available. Sign the petition here.
Petition Summary
We are a national group of health professionals interested in ensuring that the Australian Dietary Guideline review considers the latest evidence around key nutritional topics that impact population health and chronic disease.
We submit research and studies to be considered by the review, on the following key considerations:
- ADG should include information for non-healthy Australians. Given rates of chronic diseases, overweight and obesity across Australia the ADG should provide evidence-based nutrition education and support for those living with lifestyle-related ill-health. Currently, nutrition advice provided for patients with diabetes type 2 to patients is based ADG, but is not intended for this significant population
- Ultra-processed foods are harmful to health, and should not form any part of food recommendations. Remove any recommendations for ultra-processed food products.
- Therapeutic carbohydrate restriction is an effective option for metabolic health and chronic diseases, including for metabolic syndrome, obesity, fatty liver disease and diabetes type 2
- The importance of health professional education in therapeutic carbohydrate restriction for the management of chronic disease
- The importance of nutritional support and education for patients with chronic disease
- Saturated fats from whole foods are part of a healthy diet. Consider evidence around the central issue of the health effects of differing food sources of these fats.
- Re-consider evidence around margarine and seed oils for health
- Sugar is non-essential, and should not be recommended
- Highly refined carbohydrates food products should not be recommended
- Adequate dietary protein, of quality animal-based products, is an important dietary component for health
Finally, we emphasise the importance of a natural, whole-food approach to population health.
Our evidence submission for consideration in the review process is linked to here. These documents are fully referenced.
We trust that the expert committee will consider the wide range of evidence that questions several of the recommendations in the current Australian Dietary Guidelines.
This evidence submission is prepared and signed by:
Dr James Muecke, Ophthalmologist, and Australian of the Year 2020
Dr Gary Fettke, Orthopedic Surgeon
Belinda Fettke, former Registered Nurse
Dr Liz Fraser, General Practitioner
Claire McDonnell, Nutritionist
Supporting Evidence – Therapeutic Carbohydrate Restriction for Diabetes
1. Li S, Ding L, Xiao X. Comparing the Efficacy and Safety of Low-Carbohydrate Diets with Low-Fat Diets for Type 2 Diabetes Mellitus Patients: A Systematic Review and Meta-Analysis of Randomized Clinical Trials. International Journal of Endocrinology. 2021;2021:e8521756. doi:10.1155/2021/8521756
2. Yuan X, Wang J, Yang S, et al. Effect of the ketogenic diet on glycemic control, insulin resistance, and lipid metabolism in patients with T2DM: a systematic review and meta-analysis. Nutrition & Diabetes. 2020;10(1):1-8. doi:10.1038/s41387-020-00142-z
3. Meng Y, Bai H, Wang S, Li Z, Wang Q, Chen L. Efficacy of low carbohydrate diet for type 2 diabetes mellitus management: A systematic review and meta-analysis of randomized controlled trials. Diabetes Research and Clinical Practice. 2017;131:124-131. doi:10.1016/j.diabres.2017.07.006 ABSTRACT
4. Alarim RA, Alasmre FA, Alotaibi HA, Alshehri MA, Hussain SA. Effects of the Ketogenic Diet on Glycemic Control in Diabetic Patients: Meta-Analysis of Clinical Trials. Cureus. 12(10). doi:10.7759/cureus.10796
5. Turton J, Brinkworth GD, Field R, Parker H, Rooney K. An evidence-based approach to developing low-carbohydrate diets for type 2 diabetes management: a systematic review of interventions and methods. Diabetes, Obesity and Metabolism. doi:10.1111/dom.13837
6. Snorgaard O, Poulsen GM, Andersen HK, Astrup A. Systematic review and meta-analysis of dietary carbohydrate restriction in patients with type 2 diabetes. BMJ Open Diabetes Res Care. 2017;5(1):e000354. doi:10.1136/bmjdrc-2016-000354
7. Ajala O, English P, Pinkney J. Systematic review and meta-analysis of different dietary approaches to the management of type 2 diabetes. Am J Clin Nutr. 2013;97(3):505-516. doi:10.3945/ajcn.112.042457
8. Goldenberg JZ, Day A, Brinkworth GD, et al. Efficacy and safety of low and very low carbohydrate diets for type 2 diabetes remission: systematic review and meta-analysis of published and unpublished randomized trial data. BMJ. 2021;372:m4743. doi:10.1136/bmj.m4743
9. Brown A, McArdle P, Taplin J, et al. Dietary strategies for remission of type 2 diabetes: A narrative review. Journal of Human Nutrition and Dietetics. n/a(n/a). doi:10.1111/jhn.12938
10. NicholasAP, Mota AS, Lambert H, Collins AL. Restricting carbohydrates and calories in the treatment of type 2 diabetes: a systematic review of the effectiveness of ‘low carbohydrate’ interventions with differing energy levels. medRxiv. Published online May 14, 2021:2021.05.07.21256843. doi:10.1101/2021.05.07.21256843
11. Kelly T, Unwin D, Finucane F. Low-Carbohydrate Dietsinthe Management ofObesityandType2Diabetes: A Review from Clinicians Using the Approach in Practice. International Journal of Environmental Research and Public Health. 2020;17(7):2557. doi:10.3390/ijerph17072557
12. David S Ludwig, Louis J Aronne, Arne Astrup, Rafael de Cabo, Lewis C Cantley, Mark I Friedman, Steven B Heymsfield, James D Johnson, Janet C King, Ronald M Krauss, Daniel E Lieberman, Gary Taubes, Jeff S Volek, Eric C Westman, Walter C Willett, William S Yancy, Jr, Cara B Ebbeling, The carbohydrate-insulin model: a physiological perspective on the obesity pandemic, The American Journal of Clinical Nutrition, Volume 114, Issue 6, December 2021, Pages 1873–1885, https://doi.org/10.1093/ajcn/nqab270
13. Hallberg SJ, Gershuni VM, Hazbun TL, Athinarayanan SJ. Reversing Type 2 Diabetes: A Narrative Review of the Evidence. Nutrients. 2019;11(4):766. doi:10.3390/nu11040766
14. Feinman RD, Pogozelski WK, Astrup A, et al. Dietary carbohydrate restriction as the first approach in diabetes management: Critical review and evidence base. Nutrition. 2015;31(1):1-13. doi:10.1016/j.nut.2014.06.011
15. Westman EC.Type2DiabetesMellitus: A Pathophysiologic Perspective. FrontNutr.2021;8:707371. doi:10.3389/fnut.2021.707371
16. Taylor R, Ramachandran A, Yancy WS, Forouhi NG. Nutritional basis of type 2 diabetes remission. BMJ. 2021;374:n1449. doi:10.1136/bmj.n1449
17. HuntrissR, Campbell M, Bedwell C. The interpretation and effect of a low-carbohydrate diet in the management of type 2 diabetes: a systematic review and meta-analysis of randomised controlled trials. Eur J Clin Nutr. 2018;72(3):311-325. doi:10.1038/s41430-017-0019-4 ABSTRACT
18. ValenzuelaMencíaJ,FernándezCastilloR,MartosCabreraMB,Gómez-UrquizaJL,AlbendínGarcíaL, Cañadas de la Fuente GA. Diets low in carbohydrates for type 2 diabetics. Systematic review. Nutr Hosp. 2017;34(1):224-234. doi:10.20960/nh.999 ABSTRACT
19. LocatelliCAA,MulvihillEE.IsletHealth,HormoneSecretion,andInsulinResponsivitywithLow- Carbohydrate Feeding in Diabetes. Metabolites. 2020;10(11):455. doi:10.3390/metabo10110455
Trials/Studies
1. Tay J, Thompson CH, Luscombe-Marsh ND, et al. Effects of an energy-restricted low-carbohydrate, high unsaturated fat/low saturated fat diet versus a high-carbohydrate, low-fat diet in type 2 diabetes: A 2-year randomized clinical trial. Diabetes Obes Metab. 2018;20(4):858-871. doi:10.1111/dom.13164
2. Saslow LR, Daubenmier JJ, Moskowitz JT, et al. Twelve-month outcomes of a randomized trial of a moderate-carbohydrate versus very low-carbohydrate diet in overweight adults with type 2 diabetes mellitus or prediabetes. Nutr Diabetes. 2017;7(12):304. doi:10.1038/s41387-017-0006-9
3. Goday A, Bellido D, Sajoux I, et al. Short-term safety, tolerability and efficacy of a very low-calorie- ketogenic diet interventional weight loss program versus hypocaloric diet in patients with type 2 diabetes mellitus. Nutr Diabetes. 2016;6(9):e230. doi:10.1038/nutd.2016.36
4. Tay J, Luscombe-Marsh ND, Thompson CH, et al. Comparison of low- and high-carbohydrate diets for type 2 diabetes management: a randomized trial. Am J Clin Nutr. 2015;102(4):780-790. doi:10.3945/ajcn.115.112581
5. Tay J, Luscombe-Marsh ND, Thompson CH, et al. A very low-carbohydrate, low-saturated fat diet for type 2 diabetes management: a randomized trial. Diabetes Care. 2014;37(11):2909-2918. doi:10.2337/dc14- 0845
6. Chen C-Y, Huang W-S, Chen H-C, et al. Effect of a 90 g/day low-carbohydrate diet on glycaemic control, small, dense low-density lipoprotein and carotid intima-media thickness in type 2 diabetic patients: An 18- month randomised controlled trial. PLOS ONE. 2020;15(10):e0240158. doi:10.1371/journal.pone.0240158
7. Durrer C, McKelvey S, Singer J, et al. A randomized controlled trial of pharmacist-led therapeutic carbohydrate and energy restriction in type 2 diabetes. Nat Commun. 2021;12(1):5367. doi:10.1038/s41467-021-25667-4
8. Thomsen MN, Skytte MJ, Astrup A, et al. The clinical effects of a carbohydrate-reduced high-protein diet on glycaemic variability in metformin-treated patients with type 2 diabetes mellitus: A randomised controlled study. Clinical Nutrition ESPEN. Published online August 1, 2020. doi:10.1016/j.clnesp.2020.07.002 ABSTRACT
9. Yamada Y, Uchida J, Izumi H, et al. A Non-calorie-restricted Low-carbohydrate Diet is Effective as an Alternative Therapy for Patients with Type 2 Diabetes. Internal Medicine. 2014;53(1):13-19. doi:10.2169/internalmedicine.53.0861
10. AthinarayananSJ,AdamsRN,HallbergSJ,etal.Long-TermEffectsofaNovelContinuousRemoteCare Intervention Including Nutritional Ketosis for the Management of Type 2 Diabetes: A 2-Year Non- randomized Clinical Trial. Front Endocrinol. 2019;10. doi:10.3389/fendo.2019.00348
11. McKenzieA,AthinarayananS,AdamsR,VolekJ,PhinneyS,HallbergS.SUN-LB113AContinuousRemote Care Intervention Utilizing Carbohydrate Restriction Including Nutritional Ketosis Improves Markers of Metabolic Risk and Reduces Diabetes Medication Use in Patients With Type 2 Diabetes Over 3.5 Years. J Endocr Soc. 2020;4(Supplement_1). doi:10.1210/jendso/bvaa046.2302
12. GuldbrandH,LindströmT,DizdarB,etal.Randomizationtoalow-carbohydratedietadviceimproves health related quality of life compared with a low-fat diet at similar weight-loss in Type 2 diabetes mellitus. Diabetes Res Clin Pract. 2014;106(2):221-227. doi:10.1016/j.diabres.2014.08.032
13. NielsenJV,JoenssonEA.Low-carbohydratedietintype2diabetes:stableimprovementofbodyweight and glycemic control during 44 months follow-up. Nutrition & Metabolism. 2008;5(1):14. doi:10.1186/1743-7075-5-14
14. MoriconiE,CamajaniE,FabbriA,LenziA,CaprioM.Very-Low-CalorieKetogenicDietasaSafeand Valuable Tool for Long-Term Glycemic Management in Patients with Obesity and Type 2
Diabetes. Nutrients. 2021;13(3):758. doi:10.3390/nu13030758
15. RomanoL,MarchettiM,GualtieriP,etal.EffectsofaPersonalizedVLCKDonBodyCompositionand Resting Energy Expenditure in the Reversal of Diabetes to Prevent Complications. Nutrients. 2019;11(7):1526. doi:10.3390/nu11071526
16. WaltonCM,PerryK,HartRH,BerrySL,BikmanBT.ImprovementinGlycemicandLipidProfilesinType2 Diabetics with a 90-Day Ketogenic Diet. Journal of Diabetes Research. doi:10.1155/2019/8681959
17. TaylorPJ,ThompsonCH,Luscombe-MarshND,WycherleyTP,WittertG,BrinkworthGD.EfficacyofReal- Time Continuous Glucose Monitoring to Improve Effects of a Prescriptive Lifestyle Intervention in Type 2 Diabetes: A Pilot Study. Diabetes Ther. 2019;10(2):509-522. doi:10.1007/s13300-019-0572-z
18. AhmedSR,BellamkondaS,ZilbermintM,WangJ,KalyaniRR.Effectsofthelowcarbohydrate,highfatdiet on glycemic control and body weight in patients with type 2 diabetes: experience from a community- based cohort. BMJ Open Diabetes Res Care. 2020;8(1). doi:10.1136/bmjdrc-2019-000980
19. GoversE,OttenA,SchuilingB,BouwmanW,VisscherT.Effectivenessofthe6×6Dieet®inObeseDMT2 Patients Effectiveness of a Very Low Carbohydrate Ketogenic Diet Compared to a Low Carbohydrate and Energy-Restricted Diet in Overweight/Obese Type 2 Diabetes Patients. September 2019. doi:10.16966/2380-548X.158
20. DietaryInterventionforGlycaemicControlamongPatientswithType2DiabetesMellitusattheMedical Clinic, Teaching Hospital, Batticaloa, Sri Lanka. Journal of Research in Medical and Dental Science
(2021) Volume 9, Issue 8
21. SabooB,PhatakS,JethwaniP,PatelR,HasnaniD,PanchalD,ShahS,RavalV,DaveR,MishraA. Intervention of a personalized low-carbohydrate diet to reduce HbA1c level and weight in patients with Type 2 diabetes using seed-based flour as replacement for high-carbohydrate flour and foods. J Diabetol 2021;12:196-200. doi: 10.4103/jod.jod_74_20
22. KarkeeA,SinghS,ShresthaPK,ShakyaNS,ShresthaS,NiroulaS.EffectofDietaryInterventionUsingLow- Carbohydrate Diet to Manage Newly Diagnosed Type 2 Diabetes Mellitus in TUTH Hospital,
Nepal. Nepalese Medical Journal. 2021;4(1):419-423. doi:10.3126/nmj.v4i1.34710
23. WolverS,FadelK,FiegerE,etal.ClinicalUseofaReal-WorldLowCarbohydrateDietResultingin Reduction of Insulin Dose, Hemoglobin A1c, and Weight. Front Nutr. 2021;8:690855. doi:10.3389/fnut.2021.690855
24. GoversE,VisscherTLS,BouwmanW,LourensA,SchuilingaB,OttenA.CarbohydrateContentofDiet Determines Success in Type 2 Diabetes Outcomes. Metabolism – Clinical and Experimental. 2021;116. doi:10.1016/j.metabol.2020.154591
25. BanholzerN,HerzigD,PiazzaC,etal.Effectofnutritiononpostprandialglucosecontrolinhospitalized patients with type 2 diabetes receiving fully automated closed-loop insulin therapy. Diabetes, Obesity and Metabolism. 2020(n/a). doi:10.1111/dom.14187
26. Laza-CagigasR,ChanS,SumnerD,RampalT.Effectsandfeasibilityofaprehabilitationprogramme incorporating a low-carbohydrate, high-fat dietary approach in patients with type 2 diabetes: A retrospective study. Diabetes Metab Syndr. 2020;14(3):257-263. doi:10.1016/j.dsx.2020.03.010 ABSTRACT
27. Soto-MotaA,NorwitzNG,EvansR,ClarkeK,BarberTM.Exogenousketosisinpatientswithtype2 diabetes: Safety, tolerability and effect on glycaemic control. Endocrinology, Diabetes & Metabolism. n/a(n/a):e00264. doi:https://doi.org/10.1002/edm2.264
Supporting Evidence – Saturated Fats
Astrup A, Magkos F, Bier DM, Brenna JT*, de Oliveira Otto MC, Hill JO, King JC**, Mente A, Ordovas JM, Volek JS, Yusuf S, Krauss RM. Saturated Fats and Health: A Reassessment and Proposal for Food-Based Recommendations: JACC State-of-the-Art Review. J Am Coll Cardiol. 2020 Aug 18;76(7):844-857. doi: 10.1016/j.jacc.2020.05.077. Epub 2020 Jun 17.
PMID: 32562735. NOTE: Five authors are former members of the US Dietary Guidelines Advisory Committee (DGAC). The JACC named this paper in the top five papers of the year by the journal’s Editor in Chief.
*Member, 2015 Dietary Guidelines Advisory Committee, including Subcommittee on Saturated Fats
**Chair, 2005 Dietary Guidelines Advisory Committee
Astrup A, Teicholz N, Magkos F, Bier DM, Brenna JT, King JC, Mente A, Ordovas JM, Volek JS, Yusuf S, Krauss RM. Dietary Saturated Fats and Health: Are the U.S. Guidelines Evidence-Based? Nutrients. 2021 Sep 22;13(10):3305. doi: 10.3390/nu13103305. PMID: 34684304; PMCID: PMC8541481.
Schwingshackl L, Zähringer J, Beyerbach J, Werner S, W, Heseker H, Koletzko B, Meerpohl J, J: Total Dietary Fat Intake, Fat Quality, and Health Outcomes: Total Dietary Fat Intake, Fat Quality, and Health Outcomes: A Scoping Review of Systematic Reviews of Prospective Studies. Ann Nutr Metab 2021;77:4-15. doi: 10.1159/000515058. Note: NOTE: Fifty-nine SRs were included. The findings from SRs of prospective cohort studies, which frequently compare the highest versus lowest intake categories, found mainly no association of total fat, monounsaturated fatty acid (MUFA), polyunsaturated fatty acid (PUFA), and saturated fatty acid (SFA) with risk of chronic diseases. SRs of RCTs applying substitution analyses indicate that SFA replacement with PUFA and/or MUFA improves blood lipids and glycemic control, with the effect of PUFA being more pronounced.
Astrup A, Bertram H C, Bonjour J, de Groot L C, de Oliveira Otto M C, Feeney E L et al. WHO draft guidelines on dietary saturated and trans fatty acids: time for a new approach? BMJ 2019; 366 :l4137 doi:10.1136/bmj.l4137
DuBroff R, de Lorgeril M. Fat or fiction: the diet-heart hypothesis. BMJ Evid Based Med. 2021 Feb;26(1):3-7. doi: 10.1136/bmjebm-2019-111180. Epub 2019 May 29. PMID: 31142556.
Jeffery L Heileson, “Dietary Saturated Fat and Heart Disease: A Narrative Review”, Nutrition Reviews, Volume 78, Issue 6, June 2020, Pages 474-485, https://doi.org/10.1093/nutrit/nuz091
Hooper L, Martin N, Jimoh OF, Kirk C, Foster E, Abdelhamid AS. “Reduction in saturated fat intake for cardiovascular disease” 2020, Issue 5. Art. No.: CD011737. DOI: 10.1002/14651858.CD011737.pub2. Accessed 29 October 2022.
Conclusion: Saturated fats were found to have no effect on cardiovascular mortality or total mortality. Additionally, “There was little or no effect of reducing saturated fats on non‐fatal myocardial infarction or CHD mortality, but effects on total (fatal or non‐fatal) myocardial infarction, stroke and CHD events (fatal or non‐fatal) were all unclear as the evidence was of very low quality. There was little or no effect on cancer mortality, cancer diagnoses, diabetes diagnosis, HDL cholesterol, serum triglycerides or blood pressure, and small reductions in weight, serum total cholesterol, LDL cholesterol and BMI. There was no evidence of harmful effects of reducing saturated fat intakes.”
Important conflicts of interest: Lee Hooper, lead author, is a member of the World Health Organization Nutrition Guidance Expert Advisory Group (NUGAG). WHO paid for this review. In addition, WHO paid for Hooper’s travel, accommodation and expenses to attend NUGAG meetings in Geneva, China and South Korea where the evidence of effects of dietary fats on health was discussed and guidance developed. LH’s institution was given grant funding from WHO to carry out the 2019 update of this systematic review, to update a systematic review on the relationship between total fat intake and body weight and a series of systematic reviews on the health effects of polyunsaturated fatty acids. Note: The WHO has a policy of limiting saturated fat intake to 10% of calories.
Annals of Internal Medicine
Safi U. Khan, MD; Muhammad U. Khan, MD; Haris Riaz, MD; Shahul Valavoor, MD; Di Zhao, PhD; Lauren Vaughan, MD; Victor Okunrintemi, MD, MPH; Irbaz Bin Riaz, MD, MS; Muhammad Shahzeb Khan, MD; Edo Kaluski, MD; M. Hassan Murad, MD; Michael J. Blaha, MD, MPH; Eliseo Guallar, MD, DrPH; Erin D. Michos, MD, MHS, representing ten health institutions and universities in the U.S.
Conclusions (on fats): “In our analysis, the Mediterranean diet, modified dietary fat, reduced dietary fat, reduced saturated fat intake, omega-6 PUFA, or omega-3 ALA PUFA did not reduce the risk for mortality or cardiovascular outcomes.”
2. “Dietary Fats and Cardiovascular Disease: A Presidential Advisory From the American Heart Association” (2017)
Circulation (the journal of the American Heart Association, original authors of the policy advocating for reduction in saturated fats, starting in 1961)
Sacks FM, Lichtenstein AH, Wu JHY et al., for the American Heart Association.
Conclusions: In summary, randomized controlled trials that lowered intake of dietary saturated fat and replaced it with polyunsaturated vegetable oil reduced CVD by ≈30%…,Prospective observational studies in many populations showed that lower intake of saturated fat coupled with higher intake of polyunsaturated and monounsaturated fat is associated with lower rates of CVD and of other major causes of death and all-cause mortality….Replacement of saturated with unsaturated fats lowers low-density lipoprotein cholesterol, a cause of atherosclerosis, linking biological evidence with incidence of CVD in populations and in clinical trials….[W]e conclude strongly that lowering intake of saturated fat and replacing it with unsaturated fats, especially polyunsaturated fats, will lower the incidence of CVD.
[Note that this review did not look at the “hard outcome” data but arrived at its conclusions by looking exclusively at the results on LDL-cholesterol]
Nutrition Journal (2017)
Steve Hamley
Results: When pooling results from only the adequately controlled trials there was no effect for major CHD events (RR = 1.06, CI = 0.86–1.31), total CHD events (RR = 1.02, CI = 0.84–1.23), CHD mortality (RR = 1.13, CI = 0.91–1.40) and total mortality (RR = 1.07, CI = 0.90–1.26). Whereas, the pooled results from all trials, including the inadequately controlled trials, suggested that replacing SFA with mostly n-6 PUFA would significantly reduce the risk of total CHD events (RR = 0.80, CI = 0.65–0.98, P = 0.03), but not major CHD events (RR = 0.87, CI = 0.70–1.07), CHD mortality (RR = 0.90, CI = 0.70–1.17) and total mortality (RR = 1.00, CI = 0.90–1.10).
Conclusion: “Available evidence from adequately controlled randomised controlled trials suggest replacing SFA with mostly n-6 PUFA is unlikely to reduce CHD events, CHD mortality or total mortality. The suggestion of benefits reported in earlier meta-analyses is due to the inclusion of inadequately controlled trials. These findings have implications for current dietary recommendations.”
4 “Evidence from prospective cohort studies does not support current dietary fat guidelines: a systematic review and meta-analysis”
British Journal of Sports Medicine (2016)
Harcombe, Z., Baker, JS, Davies B.
Results: Across 7 studies, involving 89 801 participants (94% male), there were 2024 deaths from CHD during the mean follow-up of 11.9±5.6 years. The death rate from CHD was 2.25%. Eight data sets were suitable for inclusion in meta-analysis; all excluded participants with previous heart disease. Risk ratios (RRs) from meta-analysis were not statistically significant for CHD deaths and total or saturated fat consumption. The RR from meta-analysis for total fat intake and CHD deaths was 1.04 (95% CI 0.98 to 1.10). The RR from meta-analysis for saturated fat intake and CHD deaths was 1.08 (95% CI 0.94 to 1.25).
Conclusions: Epidemiological evidence to date found no significant difference in CHD mortality and total fat or saturated fat intake and thus does not support the present dietary fat guidelines. The evidence per se lacks generalisability for population-wide guidelines.
The BMJ (2016) starting p. 7. (on RCT data)
Ramsden, C., National Institutes of Health,. et al.
Details: This paper contains, as a separate piece of research, a systematic review and meta-analysis of clinical trials in which saturated fats were replaced by “oils rich in linoleic acid (such as corn oil, sunflower oil, safflower oil, cottonseed oil, or soybean oil).” (5 trials, 10,808 participants)
Results: “There was no evidence of benefit on mortality from coronary heart disease (hazard ratio 1.13, 95% confidence interval 0.83 to 1.54).”
Conclusion: “Although limited, available evidence from randomized controlled trials provides no indication of benefit on coronary heart disease or all cause mortality from replacing saturated fat with linoleic acid rich vegetable oils.”
6. “Reduction in saturated fat intake for cardiovascular disease,” (systematic review and meta-analysis of randomized, controlled clinical trials)
Cochrane Database Systematic Review, 2015
Hooper, L. et al.
Details: This is a systematic review and meta-analysis of randomized controlled trials, performed by the Cochrane collaboration – an independent organization of scientists. The trials reviewed include more than 59,000 participants.
Findings: The study found no statistically significant effects of reducing saturated fat on the following outcomes: all-cause mortality, cardiovascular mortality, fatal MIs (myocardial infarctions), non-fatal MIs, stroke, coronary heart disease mortality, coronary heart disease events. The one significant finding was an effect for saturated fats on cardiovascular events. However this finding lost significance when subjected to a sensitivity analysis (Table 8, page 137).
Conclusion: People who reduced their saturated fat intake were just as likely to die, or get heart attacks or strokes, compared to those who ate more saturated fat.
7. “Dietary fatty acids in the secondary prevention of coronary heart disease: a systematic review, meta-analysis and meta-regression,” (on clinical trials)
BMJ Open (2014)
Lukas Schwingshackl and Georg Hoffman, Faculty of Life Sciences, Department of Nutritional Sciences, University of Vienna, Vienna, Austria
Details: This paper compares low-fat trials to high-fat trials and only includes those with detailed reporting on cholesterol risk factors. A total of 32 trials on nearly 9,000 participants analyzed.
Conclusion: (looking only at subjects with existing CVD) The present systematic review provides no evidence (moderate quality evidence) for the beneficial effects of reduced/modified fat diets in the secondary prevention of coronary heart disease. Recommending higher intakes of polyunsaturated fatty acids in replacement of saturated fatty acids was not associated with risk reduction.
8. “Association of Dietary, Circulating, and Supplement Fatty Acids with Coronary Risk: A Systematic Review and Meta-analysis” (on observational data on all fatty acids and RCTs on supplementation with polyunsaturated fats, o3s or o6s)
Annals of Internal Medicine (2014)
Rajiv Chowdhury, MD, PhD, University of Cambridge, Samantha Warnakula, University of Cambridge, et al.
Details: RCT data reviewed is on 105,085 participants; observational data is on roughly 550,000 participants. The RCT analysis combined trials that increased either omega 3s or omega 6s.
Conclusion: “Current evidence does not clearly support cardiovascular guidelines that encourage high consumption of polyunsaturated fatty acids and low consumption of total saturated fats.”
9. “Reduced or Modified Dietary Fat For Preventing Cardiovascular Disease” (Systematic Review and Meta-analysis) (Analysis of clinical trials)
Cochrane Database Syst Review (2012), An independent organization of scientists who specialize in systematic reviews. This review is an update on one conducted in 2011.
Hooper L, Norwich Medical School, University of East Anglia, Summerbell CD, Thompson R, et al.
Conclusions: There were no clear effects of dietary fat changes on total mortality, cardiovascular mortality, stroke, total MIs or non-fatal MIs. Reducing saturated fat by reducing and/or modifying dietary fat reduced the risk of cardiovascular events by 14%,” This finding was for men only and disappeared upon the authors “Removing studies with systematic differences in care between intervention and control groups, or other dietary differences.”
PLOS Medicine (2010)
Mozaffarian D, Department of Epidemiology, Harvard School of Public Health, Micha R, Department of Epidemiology, Harvard School of Public Health, and Wallace S, Department of Epidemiology, Harvard School of Public Health.
Conclusions: “These findings provide evidence that consuming PUFA in place of SFA reduces CHD events in RCTs. This suggests that rather than trying to lower PUFA consumption, a shift toward greater population PUFA consumption in place of SFA would significantly reduce rates of CHD”
11. ”Dietary Fat and Coronary Heart Disease: Summary of Evidence From Prospective Cohort and Randomised Controlled Trials” (review of observational data and clinical trials)
Annals of Nutrition and Metabolism (2009)
Skeaff CM, PhD, Professor, Dept. of Human Nutrition, the University of Otago, Miller J.
Conclusions: “Intake of SFA was not significantly associated with CHD mortality, with a RR of 1.14 (95% CI 0.82–1.60, p = 0.431) for those in the highest compared with the lowest category of SFA intake (fig. 6). Similarly SFA intake was not significantly associated CHD events (RR 0.93, 95% CI 0.83–1.05, p = 0.269 for high vs. low categories). Moreover, there was no significant association with CHD death (RR 1.11, 95% CI 0.75–1.65, p = 0.593) per 5% TE increment in SFA intake.”
NON-SYSTEMATIC REVIEWS ON CLINICAL TRIALS
“Saturated Fat, Carbohydrate, and Cardiovascular Disease” (Review of clinical trials)
American Journal of Clinical Nutrition (2010)
Siri-Tarino PW, Children’s Hospital, Oakland Research Institute Oakland, Sun Q, MD, Departments of Nutrition and Epidemiology, Harvard School of Public Health, Hu FB, MD, Departments of Nutrition and Epidemiology, Harvard School of Public Health, et al.
Conclusions: “Although substitution of dietary polyunsaturated fat for saturated fat has been shown to lower CVD risk, there are few epidemiologic or clinical trial data to support a benefit of replacing saturated fat with carbohydrate.”
REVIEWS OF OBSERVATIONAL STUDIES (far weaker type of evidence that can show associations but cannot prove cause-and-effect relationships):
Meta-analyses and systematic reviews (in reverse chronological order):
Association between dietary fat intake and mortality from all-causes, cardiovascular disease, and cancer: A systematic review and meta-analysis of prospective cohort studies
Clinical Nutrition (2021)
Conclusions: “Diets high in saturated fat were associated with higher mortality from all-causes, CVD, and cancer, whereas diets high in polyunsaturated fat were associated with lower mortality from all-causes, CVD, and cancer.”
Note: The associations found in this review were tiny. Relative risks (RRs) were from 1.01 to 1.07 (a relative risk of 1 means zero change in risk). In epidemiology generally, RRs less than 2-3 are considered too small to be ‘real,’ due to “residual confounding”—which basically means all the hundreds other lifestyle and diet factors that could influence these outcomes that have may or may not have been measured.
Dietary total fat, fatty acids intake, and risk of cardiovascular disease: a dose-response meta-analysis of cohort studies
Lipids in Health and Disease (2019)
Yongjian Zhu, Yacong Bo & Yanhua Liu, Department of Nutrition, The first affiliated hospital of Zhengzhou University
Conclusion: “This current meta-analysis of cohort studies suggested that total fat, SFA, MUFA, and PUFA intake were not associated with the risk of cardiovascular disease. However, we found that higher TFA intake is associated with greater risk of CVDs in a dose-response fashion. Furthermore, the subgroup analysis found a cardio-protective effect of PUFA in studies followed up for more than 10 years. Dietary guidelines taking these findings into consideration might be more credible.”
British Journal of Sports Medicine (2016)
Harcombe, Z., Baker, JS, Davies B.
Results: Across 7 studies, involving 89 801 participants (94% male), there were 2024 deaths from CHD during the mean follow-up of 11.9±5.6 years. The death rate from CHD was 2.25%. Eight data sets were suitable for inclusion in meta-analysis; all excluded participants with previous heart disease. Risk ratios (RRs) from meta-analysis were not statistically significant for CHD deaths and total or saturated fat consumption. The RR from meta-analysis for total fat intake and CHD deaths was 1.04 (95% CI 0.98 to 1.10). The RR from meta-analysis for saturated fat intake and CHD deaths was 1.08 (95% CI 0.94 to 1.25).
Conclusions: Epidemiological evidence to date found no significant difference in CHD mortality and total fat or saturated fat intake and thus does not support the present dietary fat guidelines. The evidence per se lacks generalisability for population-wide guidelines.
The BMJ (Clinical Research ed.) (2015)
R.J. de Souza, Department of Clinical Epidemiology and Biostatistics, McMaster University, Chanchlani Research Centre, McMaster University, A. Mente, Population Health Research Institute, McMaster University, et al.
Conclusion: “Saturated fats are not associated with all cause mortality, CVD, CHD, ischemic stroke, or type 2 diabetes, but the evidence is heterogeneous with methodological limitations.”
Association of Dietary, Circulating, and Supplement Fatty Acids with Coronary Risk: A Systematic Review and Meta-analysis (on observational data on all fatty acids and RCTs on supplementation with polyunsaturated fats, o3s or o6s)
Annals of Internal Medicine (2014)
Rajiv Chowdhury, MD, PhD, University of Cambridge, Samantha Warnakula, University of Cambridge, et al.
Details: RCT data reviewed is on 105,085 participants; observational data is on roughly 550,000 participants. The RCT analysis combined trials that increased either omega 3s or omega 6s.
Conclusion: “Current evidence does not clearly support cardiovascular guidelines that encourage high consumption of polyunsaturated fatty acids and low consumption of total saturated fats.”
American Journal of Clinical Nutrition (2010)
Siri-Tarino PW, Children’s Hospital, Oakland Research Institute Oakland, Sun Q, MD, Departments of Nutrition and Epidemiology, Harvard School of Public Health, Hu FB, MD, Departments of Nutrition and Epidemiology, Harvard School of Public Health, et al.
Conclusions: “A meta-analysis of prospective epidemiologic studies showed that there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD. More data are needed to elucidate whether CVD risks are likely to be influenced by the specific nutrients used to replace saturated fat.”
A Systematic Review of the Evidence Supporting a Causal Link Between Dietary Factors and Coronary Heart Disease (review of observational data and clinical trials)
Archives of Internal Medicine (2009)
Andrew Mente, MA, PhD, Associate Professor, Department of Clinical Epidemiology & Biostatistics, McMaster University, Lawrence de Koning, Clinical Assistant Professor, Department of Pathology and Laboratory Medicine, Pediatrics, University of Calgary, et al.
Conclusions: “The evidence supports a valid association of a limited number of dietary factors and dietary patterns with CHD…. Insufficient evidence (< or =2 criteria) of association is present for intake of supplementary vitamin E and ascorbic acid (vitamin C); saturated and polyunsaturated fatty acids;…”
Dietary Fat and Coronary Heart Disease: Summary of Evidence From Prospective Cohort and Randomised Controlled Trials (review of observational data and clinical trials)
Annals of Nutrition and Metabolism (2009)
Skeaff CM, PhD, Professor, Dept. of Human Nutrition, the University of Otago, Miller J.
Conclusions: “Intake of SFA was not significantly associated with CHD mortality, with a RR of 1.14 (95% CI 0.82–1.60, p = 0.431) for those in the highest compared with the lowest category of SFA intake (fig. 6). Similarly SFA intake was not significantly associated CHD events (RR 0.93, 95% CI 0.83–1.05, p = 0.269 for high vs. low categories). Moreover, there was no significant association with CHD death (RR 1.11, 95% CI 0.75–1.65, p = 0.593) per 5% TE increment in SFA intake.”
NON-SYSTEMATIC REVIEWS OF OBSERVATIONAL STUDIES:
Annual Review of Nutrition (2015)
Patty W. Siri-Tarino, PhD, Sally Chiu, PhD, Nathalie Bergeron, PhD, and Ronald M. Krauss, PhD, Atherosclerosis Research Program, Children’s Hospital Oakland Research Institute, Oakland, California
Conclusions: “Replacement of SFAs with polyunsaturated fatty acids has been associated with reduced CVD risk, although there is heterogeneity in both fatty acid categories. In contrast, replacement of SFAs with carbohydrates, particularly sugar, has been associated with no improvement or even a worsening of CVD risk…
Replacement of SFAs with CHOs [carbohydrates] has not been associated with benefit and may be associated with increased CVD risk….The effects of various SFA replacement scenarios on CVD risk factors other than lipids and lipoproteins are ambiguous…
SINGLE OBSERVATIONAL STUDIES OR ECOLOGICAL DATA:
United States Dietary Trends Since 1800: Lack of Association Between Saturated Fatty Acid Consumption and Non-communicable Diseases
Frontiers in Nutrition (2022)
https://doi.org/10.3389/fnut.2021.748847
Joyce H. Lee, Miranda Duster, Timothy Roberts, and Orrin Devinsky
Conclusion (relevant to saturated fats): “Saturated fats from animal sources were inversely correlated with the prevalence of NCDs [Non-communicable diseases].”
The PURE Study: largest-ever epidemiological study, contradicts diet-heart hypothesis
Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study
The Lancet (2017)
Mahshid Dehghan, Andrew Mente, Xiaohe Zhang, et al., on behalf of the Prospective Urban Rural Epidemiology (PURE) study investigators*
Interpretation of findings: “High carbohydrate intake was associated with higher risk of total mortality, whereas total fat and individual types of fat were related to lower total mortality. Total fat and types of fat were not associated with cardiovascular disease, myocardial infarction, or cardiovascular disease mortality, whereas saturated fat had an inverse association with stroke. Global dietary guidelines should be reconsidered in light of these findings.”
LONGEST-EVER SINGLE OBSERVATIONAL STUDY:
The Boyd Orr Cohort study: longest-ever epidemiological study, contradicts the diet-heart hypothesis
”Diet in childhood and adult cardiovascular and all cause mortality: the Boyd Orr cohort”
Heart (2005)
Ness AR, Maynard M, Frankel S, Smith GD, Frobisher C, Leary SD, Emmett PM, Gunnell D.
Methods: 4028 people (from 1234 families) took part in Boyd Orr’s survey of family diet and health in Britain between 1937 and 1939 and were followed up through the National Health Service central register to 2000.
Conclusions: No significant associations for childhood saturated fat intake and cardiovascular mortality or any cause of death. For all-cause mortality the rate ratio between the highest and lowest quartiles of saturated fat intake was 0.91 (95% CI 0.70 to 1.17, p for trend 0.2) after adjustment for age, sex, and energy intake.
Alternative Dietary Patterns – Restricted Carbohydrate Diet
Volek JS, Phinney SD, Krauss RM, Johnson RJ, Saslow LR, Gower B, Yancy WS Jr, King JC, Hecht FM, Teicholz N, Bistrian BR, Hamdy O. Alternative Dietary Patterns for Americans: Low-Carbohydrate Diets. Nutrients. 2021 Sep 22;13(10):3299. doi: 10.3390/nu13103299. PMID: 34684300; PMCID: PMC8537012.
Also a list of review papers on saturated fats (not quite up to date) is on our website. The two papers above have incorporated all these other review papers in their analyses, but you might as well include all of these to show the extent of the efforts that have been made to review this evidence.
On vegetable oilsThe above evidence on saturated fats examines these fats compared to vegetables oils, and the conclusion is that there is no advantage of vegetable oils over saturated fats. This body of science, demonstrates that there is a lack of evidence for our current policies recommending the replacement of sat fats with polyunsaturated fats.
An additional body of evidence demonstrates the harms of vegetable oils, but I don’t have a handly list of citations. Cate Shanahan or Tucker Goodrich might have something.
Carbohydrate is not an essential nutrient i.e. something that must be consumed. The best reference for this is the US document “The panel on macronutrients”, which states: “The lower limit of dietary carbohydrate compatible with life apparently is zero, provided that adequate amounts of protein and fat are consumed” [The Panel on Macronutrients. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients): The National Academies Press, 2005:1357.]
Healthy fats – Seed oils
Diets high in linoleic acid lead to higher oxidative stress, oxidation of cardiolipin, electron transport chain malfunction, and increased reactive oxygen species, which collectively leads directly to insulin resistance, [i][ii][iii] obesity, and non-alcoholic fatty liver disease. [iv]
[i] Li J, Romestang C, Han X, et al. Cardiolipin Remodeling by ALCAT1 Links Oxidative Stress and Mitochondrial Dysfunction to Obesity. Cell Metabolism. 2010;12:154-165.
[ii] Houstis N, Rosen ED, Lander ES. Reactive oxygen species have a causal role in multiple forms of insulin resistance. Nature. 2006;440:944-948.
[iii] Meigs JB, Larson MG, Fox CS, et al. Association of oxidative stress, insulin resistance, and diabetes risk phenotypes. Diabetes Care, Oct 2007.
[iv] Pérez-Carreras M, Del Hoyo P, Martin MA, et al. Defective hepatic mitochondrial respiratory chain in patients with nonalcoholic steatohepatitis. Hepatology. 2003;38:999-1007.
