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Rebuttal to the Physician’s Committee for Responsible Medicine article: “Keto Diet Is Dangerous for Veterans with Diabetes”

A recent article by vegan advocacy group PCRM has attacked using low-carb for veterans with diabetes. In this article, researcher Cliff Harvey provides a rebuttal to the PCRM arguments against LCHF for diabetes.

The Physicians Committee for Responsible Medicine (PCRM)

https://www.pcrm.org/news/blog/va-secretary-wilkie-keto-diet-dangerous-veterans-diabetes

Article Summary

Instead of protecting veterans’ health, the Department of Veterans Affairs is considering putting it at risk by partnering with Virta Health Corp. to place veterans with type 2 diabetes on a low-carb, ketogenic (keto) diet, which current science suggests is a risky choice for diabetes.

A keto diet also carries serious short- and long-term health risks including impaired artery function, elevated LDL cholesterol, nutrient deficiencies, increased risk of colon cancer, and increased risk of death.

Read the letter I sent to Veteran Affairs Secretary Robert Wilkie today, which describes the dangers of a keto diet and urges the VA to instead use the proven power of plant-based nutrition to help veterans fight diabetes.


Comment

Firstly, it is important to recognise the disingenuous naming of this organisation. The ‘Physicians Committee for Responsible Medicine’ (PCRM) sounds like a group of evidence-based physicians upholding good standards in medicine… but this couldn’t be further from the truth. The PCRM is a vegan advocacy group consisting of medical doctors and other practitioners committed to a plant-based lifestyle. While I have nothing against people wanting to be vegan for a variety of reasons, I do think that the name of this organisation is both patronising and disingenuous.

Why not just call it what it is?

My main ‘beef’ though with this group is that they cherry pick the data and deliberately misrepresent the science in order to push a vegan agenda. Now, I’m all for a vegan diet if and where it has demonstrable benefits to health but NOT when there are better alternatives to it for a particular outcome.

In this case, the Department of Veterans Affairs in the US is exploring a partnership with the Virta Group to use low-carbohydrate and ketogenic diets to treat type 2 diabetes in veterans. To me, this seems a sound idea.

In the letter to Secretary Wilkie (download the letter below), vegan advocate, Dr Neil Barnard outlines the reasons for PCRM opposition to low-carb and keto interventions. These defy the current state of knowledge for the treatment of metabolic syndrome and diabetes.

Claim: Keto diets cause diabetes by contributing to a build-up of liver and muscle fat

This claim is patently false. It is a known fact that triglyceride levels (fats in the blood) and the de novo (in the body) creation of fat in the liver are both reduced most by a low-carb diet, with the greatest benefits seen with the greatest restriction of carbohydrate. (In other words, the more you reduce carbs, the more you reduce fats in the blood). This triglyceride lowering effect (when compared to low-fat diets) has been demonstrated time and time again.1-6  There are also persistent (long-term) benefits to overall fat levels in the body from keto- and low-carb vs low-fat diets over the long-term.6

With respect to visceral and liver-fat, animal research has strongly suggested that sugar and carbohydrate overall are the major contributors to these, with lower-carb interventions reducing liver and visceral fat levels, and a recent study has confirmed these findings in humans, with a significantly greater loss of both visceral and liver fat (and greater improvement in blood measures of cardiometabolic health) from a low-carb vs low-fat intervention over 18 months.7

Claim: Keto diets reduce insulin sensitivity

This claim is actually true! But disingenuous. There IS a drop, in insulin sensitivity if you have followed a ketogenic diet for some time. But this drop is transient and is due to the low levels of dietary glucose that have been present in the diet. Overall, outside of an oral glucose tolerance test administered in a ketogenic diet, there is actually lower insulin levels and general improvement in glucose and insulin control resulting from a low-carbohydrate diet.

Claim: Keto diets result in ‘massive’ increases in LDL cholesterol

Again, this claim is true yet inconsequential. Low-density lipoprotein is a carrier for cholesterol. Think of it as the ‘bus’ that carries cholesterol out to tissue to do its valuable job of patching up tissue and providing substrates for the creation of hormones. LDL is not in and of itself bad! For most people, a small rise in LDL and total cholesterol from a keto diet is not dangerous at all. When we look at markers of cardiovascular risk, modest increases in LDL and cholesterol pale in comparison to triglyceride (fat) concentrations in the blood, which are most convincingly linked to the incidence of and mortality from cardiovascular disease.8-10

When we look at markers of cardiovascular risk, modest increases in LDL and cholesterol pale in comparison to triglyceride (fat) concentrations

For example, every 1 mmol/L increase in triglycerides is associated with a > 12% increase in risk, for both cardiovascular disease mortality and all-cause mortality.10 Some people will have greater increases in both LDL and cholesterol (due to genetic factors) from a keto diet. This can typically be rectified by modifying fat intake to more polyunsaturated and monounsaturated fats and the replacement of some red meat with white, and coconut oil and butter substituted for hemp, flax, and olive oils.

For example, every 1 mmol/L increase in triglycerides is associated with a > 12% increase in risk, for both cardiovascular disease mortality and all-cause mortality.10 Some people will have greater increases in both LDL and cholesterol (due to genetic factors) from a keto diet. This can typically be rectified by modifying fat intake to more polyunsaturated and monounsaturated fats and the replacement of some red meat with white, and coconut oil and butter substituted for hemp, flax, and olive oils.

Claim: A ketogenic diet removes valuable phytochemicals and essential nutrients for plant-foods

No, it doesn’t. This is a misinterpretation of what keto actually is. I have prescribed ketogenic diets for 21 years and never have I had some reduce vegetable intake. Almost all (with the odd exception for people who do not tolerate vegetable matter well) ‘good’ diets include lots of vegetables and other nutrient-dense foods. Ketogenic diets based on natural, unrefined foods, include all the essential and secondary nutrients that are necessary for optimal health.  A recent study by my colleague Dr Caryn Zinn at AUT University has confirmed that a low-carb diet is replete with all micronutrients.11

Claim: Low-carbohydrate diets result in early death

The 2013 systematic review by Noto and colleagues is used to support this claim.12 The problem with using pooled results from observational studies is that there is little control over the methodology. We could summarise to say, ‘garbage in = garbage out’. When looking at all-cause mortality from a diet, we need to look at the research in the order of:

  1. What do we see in populations over time?
  2. What does the data actually show us?
  3. Why might this be occurring? (I.e. what is the proposed mechanism)
  4. Does this match what we see in randomised controlled trials? (I.e. is the proposed mechanism plausible?)

In the case of modifying carbohydrate intake, the largest published observational study actually showed a reduced likelihood of death with lower carbohydrate intake and higher fat intake.13 However, the following year, the Dietary carbohydrate intake and mortality: a prospective cohort study using data from the ARIC cohort suggested that both extremes of carbohydrate intake (low and high) were associated with risk of early death.14 When we look at the food data (as much as is available anyway) a common theme becomes clear. Those who eat ultra-processed food are at the greatest risk.

When we look at the food data (as much as is available anyway) a common theme becomes clear. Those who eat ultra-processed food are at the greatest risk.

When we correct for that, there is little difference overall between lower- and higher-carbohydrate diets. However, there are significant differences for specific populations, and those at risk of diabetes, or with diabetes control blood glucose better and have better outcomes from low-carb and keto diets.

What is the best diet for metabolic syndrome and diabetes?

Low-carbohydrate diets are the best treatment option for those with metabolic syndrome (prediabetes) and diabetes.

Low-carbohydrate diets have a significant effect on blood glucose levels and glucose control,15 and they consistently improve cardiometabolic risk factors such as triglycerides and HDL cholesterol, more than standard-care, or higher-carbohydrate diets.16 Those with metabolic syndrome are also likely to stick to low-carb diets more easily than low-fat.17

Overall, low-carbohydrate and ketogenic diets are more effective than other dietary interventions for the treatment and management of diabetes with an approximately 150% greater reduction in HbA1c as compared to higher-carb diets.18

Overall, low-carbohydrate and ketogenic diets are more effective than other dietary interventions for the treatment and management of diabetes

References

1.            Santos FL, Esteves SS, da Costa Pereira A, Yancy Jr WS, Nunes JPL. Systematic review and meta-analysis of clinical trials of the effects of low carbohydrate diets on cardiovascular risk factors. Obesity Reviews. 2012;13(11):1048-66.

2.            Huntriss R, 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. 2017.

3.            Hession M, Rolland C, Kulkarni U, Wise A, Broom J. Systematic review of randomized controlled trials of low-carbohydrate vs. low-fat/low-calorie diets in the management of obesity and its comorbidities. Obes Rev. 2009;10(1):36-50.

4.            Hu T, Mills KT, Yao L, Demanelis K, Eloustaz M, Yancy JWS, et al. Effects of Low-Carbohydrate Diets Versus Low-Fat Diets on Metabolic Risk Factors: A Meta-Analysis of Randomized Controlled Clinical Trials. American Journal of Epidemiology. 2012;176(suppl_7):S44-S54.

5.            Mansoor N, Vinknes KJ, Veierød MB, Retterstøl K. Effects of low-carbohydrate diets v. low-fat diets on body weight and cardiovascular risk factors: a meta-analysis of randomised controlled trials. British Journal of Nutrition. 2016;115(3):466-79.

6.            Hashimoto Y, Fukuda T, Oyabu C, Tanaka M, Asano M, Yamazaki M, et al. Impact of low-carbohydrate diet on body composition: meta-analysis of randomized controlled studies. Obesity Reviews. 2016;17(6):499-509.

7.            Gepner Y, Shelef I, Komy O, Cohen N, Schwarzfuchs D, Bril N, et al. The beneficial effects of Mediterranean diet over low-fat diet may be mediated by decreasing hepatic fat content. Journal of Hepatology.

8.            Ravnskov U, Diamond DM, Hama R, Hamazaki T, Hammarskjold B, Hynes N, et al. Lack of an association or an inverse association between low-density-lipoprotein cholesterol and mortality in the elderly: a systematic review. BMJ open. 2016;6(6):e010401.

9.            Harcombe Z, Baker JS, Cooper SM, Davies B, Sculthorpe N, DiNicolantonio JJ, et al. Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis. Open Heart. 2015;2(1).

10.         Liu J, Zeng F-F, Liu Z-M, Zhang C-X, Ling W-h, Chen Y-M. Effects of blood triglycerides on cardiovascular and all-cause mortality: a systematic review and meta-analysis of 61 prospective studies. Lipids Health Dis. 2013;12(1):159.

11.         Zinn C, Rush A, Johnson R. Assessing the nutrient intake of a low-carbohydrate, high-fat (LCHF) diet: a hypothetical case study design. BMJ open. 2018;8(2):e018846.

12.         Noto H, Goto A, Tsujimoto T, Noda M. Low-carbohydrate diets and all-cause mortality: a systematic review and meta-analysis of observational studies. PloS one. 2013;8(1):e55030.

13.         Dehghan M, Mente A, Zhang X, Swaminathan S, Li W, Mohan V, et al. Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study. Lancet. 2017;390(10107):2050-62.

14.         Seidelmann SB, Claggett B, Cheng S, Henglin M, Shah A, Steffen LM, et al. Dietary carbohydrate intake and mortality: a prospective cohort study and meta-analysis. The Lancet Public health. 2018;3(9):e419-e28.

15.         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;131:124-31.

16.         Gardner CD, Trepanowski JF, Del Gobbo LC, Hauser ME, Rigdon J, Ionnidis JPA, et al. Effect of low-fat vs low-carbohydrate diet on 12-month weight loss in overweight adults and the association with genotype pattern or insulin secretion: The DIETFITS randomized clinical trial. JAMA. 2018;319(7):667-79.

17.         McClain AD, Otten JJ, Hekler EB, Gardner CD. Adherence to a low-fat vs. low-carbohydrate diet differs by insulin resistance status. Diabetes Obes Metab. 2013;15(1):87-90.

18.         Jirapinyo P, Devery A, Sarker S, Williams G, Thompson CC. Tu1931 – A Comparison of Diet Plan Outcomes in Diabetes Management: A Systematic Review and Meta-Analysis. Gastroenterology. 2018;154(6, Supplement 1):S-1057-S-8.

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