Paleo and low-carbohydrate diets for diabetes: today's fads or tomorrow s advice?

Transcription

1 Paleo and low-carbohydrate diets for diabetes: today's fads or tomorrow s advice? Associate Professor Tim Crowe School of Exercise and Nutrition Sciences Deakin University tim.crowe@deakin.edu.au 1

2 Topics to be Covered 1. The rationale for the Paleo diet 2. Paleo for diabetes 3. Paleo wins and fails 4. Low-carb diets: the briefest of overviews 5. The best diet for diabetes is 2

3 What is the Paleo Diet? Based on assumed eating habits of our ancestors in the Palaeolithic period (2.5 million and 10,000 years ago) before advent of agriculture and industry Based on two central ideas: 1. We are genetically adapted to eat particular kinds of foods 2. To stay healthy and avoid the chronic diseases of modernity we need to eat like our ancestors Is more of a lifestyle than a diet 3

4 Paleo Diet in a Nutshell 4

5 Paleo for Diabetes? Several small studies showing it may improve insulin sensitivity, weight and several CVD risk factors in the short-term Study 1 * 3 month RCT crossover of 13 patients with T2DM (mean HbA 1C 6.6%, 9 yrs duration and on OHAs) of Paleo diet vs standard diet for diabetes around dietary guidelines Greater improvements on Paleo diet with HbA 1C ( 0.4 percentage points), and improved TG, diastolic BP, weight (3kg) and waist circumference (4cm) and higher HDL Paleo diet lower in energy, CHO, GI, glycaemic load, saturated fat, and calcium * Jӧnsson T et al. Cardiovascular Diabetology 2009;8:35 5

6 Paleo for Diabetes? Study 2 * 12 week study of 29 people with IHD and IGT or T2DM Randomised to a Paleo or Mediterranean style diet Both groups saw a benefit in glucose tolerance and body weight Greater benefits in glucose tolerance in Paleo group independent of weight change Similar benefits on HOMA-IR Energy intake was 25% lower in Paleo group 3 dropouts in Paleo group, none in other group * Lindeberg S et al. Diabetologia 2007;50:

7 2-Year Paleo RCT 70 obese post-menopausal women assigned ad libitum Paleo diet or Nordic Nutrition Recommendations 12 group sessions over the study More fat loss in Paleo group at 6 months, but not 2 years Greater TG in Paleo group, but no other differences in other metabolic measures Mellberg C et al. Eur J Clin Nutr 2014;68:

8 Paleo Reality Humans are continually evolving to suit our environment e.g. lactose tolerance increased with exposure to dairy What we eat today is drastically different to its Paleo predecessor There is no one Paleo Diet - varies immensely based on world region Humans ate what was available to them out of necessity, not out of choice 8

9 Source: 9

10 Paleo Diet: Really? 10

11 Paleo Lifestyle A true Paleo lifestyle also includes plenty of physical activity from hunting and gathering 11

12 Paleo Pros Emphasises whole foods, lean proteins, vegetables, fruits, nuts, seeds, and other healthy fats - a big improvement over the typical Western diet In Australia, 1/3 of daily kilojoules* is from foods of little nutritional value (discretionary foods) - not ancestral foods, nor foods that any nutrition expert, regardless of dietary persuasion, would ever recommend If a person is dedicated and happy to forgo many wonderful staple foods, they can achieve healthy eating and weight control and potentially improve diabetes control * Australian Health Survey

13 Paleo Cons There is no single Paleo diet Excludes dairy, high fibre grains and legumes (evidence grains and legumes were eaten from stone tools analysis at Paleo sites) Whole grains and legumes improve health through improved blood lipids, better blood glucose control and less inflammation (but refined grains to inflammation) More reliant on meat Cost Unhealthy focus on good and bad foods 13

14 Paleo itself is Evolving Paleo lifestyle versus Paleo Diet Paleo advocates coming to appreciate and encourage the addition of moderate amounts of starch, dark chocolate, red wine and even some dairy (butter, yoghurt, cheese) These additions make life much more pleasant and make healthy eating more attractive and achievable This new leniency may partly explain why the Paleo diet continues to gain traction in mainstream nutrition circles 14

15 Low-Carbohydrate Diets Definition? Cover a diverse range of diets, with food choices changing as degree of CHO restriction changes Can just limit carbohydrates (~40% of energy), restrict to a set level e.g. 25% of energy or <130 g/day, or aim to be ketogenic at <50 g/day grains, starch, sugar and fat and protein Can be effective in short-term studies <6mo, but as degree of restriction increases, adherence declines Two 1-year RCT studies * : no superior benefit of low-carb on weight, lipids and HbA 1C *Larsen RN et al. Diabetologia 2011;54: and Krebs JD et al. Diabetologia 2012;55:

16 The Latest Study 115 obese adults with T2DM randomised for 24 wk to hypocaloric low-carb (14% CHO, <50g) or energy matched low-fat diet (53% CHO). Both <10% sat. fat and included exercise What was similar Completion rates (~80%), weight loss (~12 kg), BP, LDL-C and fasting glucose What was different (only in those with HbA 1C > 7.8%) Better TG, HbA 1C (-2.6 vs -1.9), and glycaemic variability changes in low-cho group Tay JRN et al. Diabetes Care 2014 Epub July 28, 2014 doi: /dc

17 Not Everyone is Average In all diet comparison studies, results are averages some do better and others worse on each diet. How to narrow this down? Several studies * indicate that those with insulin resistance may do better on low-cho diet vs low-fat diet (the opposite is also true!) * Gardner CD. Tailoring dietary approaches for weight loss Int J Obesity Suppl 2012;2:S11-S15 17

18 The Best Diet for Diabetes? Systematic review and meta-analysis of 20 RCTs of 7 different diets followed for >6 months Low-CHO, low-gi, Mediterranean, and high protein diets all effective in HbA1c by percentage points with Mediterranean diet showing largest effect size Dietary behaviors and choices are often personal, and it is usually more realistic for a dietary modification to be individualized rather than to use a one-size-fits-all approach for each person. Ajala O et al. Systematic review and meta-analysis of different dietary approaches to the management of type 2 diabetes Am J Clin Nutr 2013;97:

19 Practice Implications 1. There is no one size fits all approach for diet and diabetes 2. Different dietary approaches for diabetes travel on different roads, of varying surface qualities, but arrive at the same destination 3. Just cutting back on sugary foods/drinks, highly refined carbohydrate sources, serving size of meals and eating more non-starchy vegetables makes a diet low-carb and approaches Paleo too 4. A diet label can be a useful handle, but tailor approach to the individual with a firm eye on nutritional quality 19