Metabolic Health Evidence Base

Evidence for outlining why we support a low-carb diet

Brown, A., McArdle, P., Taplin, J., Unwin, D., Unwin, J., Deakin, T., … & Mellor., D. (2020). Dietary strategies for remission of type 2 diabetes: A narrative.

Summary

• Narrative review supporting the use of a low-carb diet to achieve remission from Type 2 diabetes.

Feinman, R. D., Pogozelski, W. K., Astrup, A., Bernstein, R. K., Fine, E. J., Westman, E. C., … & Worm, (2015). Dietary carbohydrate restriction as the first approach in diabetes management: critical review and evidence base. Nutrition, 31, 1-13.

Summary

• A review paper highlights that a restricted-carb diet is an effective means of managing high blood sugar and Type 2 diabetes.
• The review also defines a ‘low-carb’ diet as 130g of carbohydrate per day or less. This is what we are working on at Combe Grove. There has previously been no consensus on the definition of ‘low-carb’.

Hussain, T. A., Mathew, T. C., Dashti, A. A., Asfar, S., Al-Zaid, N., & Dashti, H. M. (2012). Effect of low calorie versus low-carbohydrate ketogenic diet in type 2 diabetes. Nutrition, 28, 1016-1021.

Summary

• Evidence that a low-carbohydrate diet is effective in promoting weight loss and reducing blood sugar over 24 weeks.

Centers for Disease Control and Prevention. (2004). Trends in intake of energy and macronutrients United States: 1971 to 2000, JAMA, 291, 1193-1194.

Summary

• The study followed 5000 Americans from 1974 to 2000.
• Evidence that the increase in Type 2 diabetes is linked to an increase in carbohydrates in the Western diet, and not an increase in fat. Suggest that reducing carbs in our diet may therefore help to tackle rising diabetes cases.

Westman, E. C., Yancy, W. S., Mavropoulos, J. C., Marquart, M., & McDuffie, J. R. (2008). The effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitus. Nutrition & metabolism, 5, 1-9.

Summary

• Evidence that a low-carb diet is an effective tool for achieving weight loss and a reduction in HbA1c, a measure of the average sugar content of the blood over 12 weeks. More effective than a low-calorie diet.

 Evidence outlining why we recommend a protein source at each meal

Krieger, J. W., Sitren, H. S., Daniels, M. J., & Langkamp-Henken, B. (2006). Effects of variation in protein and carbohydrate intake on body mass and composition during energy restriction: a meta-regression. The American journal of clinical nutrition, 83(2), 260-274.

Summary

• Evidence that a high protein diet helps to prevent loss of lean tissue (muscle mass) when following a low carb diet. Sustaining adequate muscle mass is important for protecting against Type 2 diabetes, especially as we get older.

Phillips, S. M., Paddon-Jones, D., & Layman, D. K. (2020). Optimizing adult protein intake during catabolic health conditions. Advances in Nutrition, 11, 1058-1069.

Summary

• Review outlining the benefits of higher protein diets for optimising health during ageing, inactivity, bed rest, or metabolic dysfunction such as type 2 diabetes.

Areta, J. L., Burke, L. M., Ross, M. L., Camera, D. M., West, D. W., Broad, E. M., … & Coffey, V. G. (2013). Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis. The Journal of Physiology, 591, 2319-2331.

Summary

• Evidence that protein ingestion is most effective at stimulating muscle protein synthesis when a moderate amount of protein is consumed at every meal.

Evidence that protein increases satiety and may reduce caloric intake

Bowen J, Noakes M, Trenerry C, Clifton PM 2006 Energy intake, ghrelin and cholecystokinin after different carbohydrate and protein preloads in overweight men. Journal of Clinical Endocrinology and Metabolism, 91, 1477–1483.

Summary

• The study showed that consuming a protein-rich beverage before a meal led to reduced appetite and reduced calorie consumption when compared to a glucose-rich beverage.

Foster-Schubert, K. E., Overduin, J., Prudom, C. E., Liu, J., Callahan, H. S., Gaylinn, B. D., Thorner, M.O., & Cummings, D. E. (2008). Acyl and total ghrelin are suppressed strongly by ingested proteins, weakly by lipids, and biphasically by carbohydrates. The Journal of Clinical Endocrinology and Metabolism, 93, 1971–1979.

Summary

• Study shows that a protein-rich drink effectively suppresses the hunger hormone ghrelin over six hours, whereas a carbohydrate-rich drink suppresses ghrelin for three hours followed by a marked overshoot above baseline.

Evidence outlining why we support the inclusion of natural fats in our diet and do not support a low-fat diet:

Howard, B. V., Van Horn, L., Hsia, J., Manson, J. E., Stefanick, M. L., Wassertheil-Smoller, S., and Kotchen, J. M. (2006). Low-fat dietary pattern and risk of cardiovascular disease: the Women’s Health Initiative Randomized Controlled Dietary Modification Trial. JAMA, 295, 655-666.

Summary

• Study of 48,000 post-menopausal women
• Evidence that a low-fat diet does not reduce the risk of coronary heart disease, and cardiovascular disease, which are risk factors for Type 2 diabetes.

Deakin, T., & Garden, L. (2015). Saturated fat doesn’t increase coronary heart disease in people with diabetes. Practical Diabetes, 32, 254-260.

Summary

• A review of studies considers the relationship between saturated fat in the diet, such as that found in animal products such as meat and dairy, and the risk of coronary heart disease. Concluded that saturated fat in the diet does not increase the risk of CHD.

Siri-Tarino, P. W., Sun, Q., Hu, F. B., & Krauss, R. M. (2010). Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. The American journal of clinical nutrition, 91(3), 535-546.

Summary

• During 5 to 23 years of follow up of 350,000 subjects, 11,000 developed CHD or stroke. Intake of saturated fat was not associated with an increased risk of CHD, stroke, or CVD.

Evidence that ingestion of foods rich in fats may slow the rate of release of glucose into the blood

Jenkins, D. J., Kendall, C. W., Josse, A. R., Salvatore, S., Brighenti, F., Augustin, L. S., … & Rao, A. V. (2006). Almonds decrease postprandial glycemia, insulinemia, and oxidative damage in healthy individuals. The Journal of Nutrition, 136, 2987-2992.

Summary

• Studies show that eating raw, unblanched almonds, a source of fat, with white bread increases satiety scores compared to eating white bread alone.
• Peak post-prandial blood glucose levels were significantly lower following a meal of almonds and white bread than a meal of white bread alone.

Lilly, L. N., Heiss, C. J., Maragoudakis, S. F., Braden, K. L., & Smith, S. E. (2019). The effect of added peanut butter on the glycemic response to a high–Glycemic index meal: A pilot study. Journal of the American College of Nutrition, 38, 351-357.

Summary

• Study shows that adding two tablespoons of peanut butter, a source of fat, to a meal of white bread and apple juice (high carb meal) significantly attenuated the magnitude of blood glucose spikes and overall glycaemic response compared with the high carb meal alone.

Shukla, A. P., Dickison, M., Coughlin, N., Karan, A., Mauer, E., Truong, W., … & Aronne, L. J. (2019). The impact of food order on postprandial glycaemic excursions in prediabetes. Diabetes, Obesity and Metabolism, 21, 377-381.

Summary

• Studies show that, in a prediabetic population, eating protein and vegetables before carbohydrate confers a significant reduction in postprandial glycaemia compared with eating carbohydrates before protein and vegetables.
• Effects were largely put down to the effect of fat and fibre content of meals, however.

Crouch, M. A., & Slater, R. T. (2016). Almond “appetizer” effect on glucose tolerance test (GTT) results. The Journal of the American Board of Family Medicine, 29, 759-766.

Summary

• Studies show that, in a prediabetic population, eating almonds 30 mins before an oral glucose tolerance test reduces postprandial glycaemia. This was actually attributed to fibre and fat content.

Evidence outlining why we recommend intake of non-starchy vegetables, broccoli, cauliflower, asparagus etc, as the largest component of any given meal

Martin, K. E. (2017). Glycaemic response to varying the proportions of starchy foods and non-starchy vegetables within a meal: A randomised controlled trial (Doctoral dissertation, University of Otago).

Summary

• Evidence that meals with larger proportions of starchy carbs, pasta/rice, and smaller portions of non-starchy vegetables cause the greatest increase in blood sugar levels. Meals that contain smaller proportions of starchy carbs and larger proportions of non-starchy vegetables have the lowest impact on blood sugar.

Moore, L. L., Singer, M. R., Bradlee, M. L., & Daniels, S. R. (2016). Adolescent dietary intakes predict cardiometabolic risk clustering. European Journal of Nutrition, 55, 461-468.

Summary

• Evidence that eating plenty of non-starchy vegetables earlier in life may have a protective effect against risk factors for Type 2 diabetes and cardiovascular disease

Evidence that eating a diverse, plant rich diet is associated with a healthy and diverse microbiome

Van der Merwe, M. (2021). Gut microbiome changes induced by a diet rich in fruits and vegetables. International Journal of Food Sciences and Nutrition, 72, 665-669.

Summary

• Review paper outlining the evidence for a link between habitual intake of diverse fruit and veg and increased microbial diversity within the gut, with possible implications for reduced chronic disease.

Evidence that eating plenty of non-starchy vegetables is associated with reduced inflammation within the body

Menni, C., Louca, P., Berry, S. E., Vijay, A., Astbury, S., Leeming, E. R., … & Valdes, A. M. (2021). High intake of vegetables is linked to lower white blood cell profile and the effect is mediated by the gut microbiome. BMC Medicine, 19, 1-10.

Summary

• Studies show that a habitual diet high in vegetables, but not fruits, is linked to a lower inflammatory profile for white blood cells, and a fifth of the effect is mediated by the effects of vegetable intake on the gut microbiome.

Evidence that eating a diverse, plant-rich diet is associated with a healthy and diverse microbiome van der Merwe, M. (2021). Gut microbiome changes induced by a diet rich in fruits and vegetables. International Journal of Food Sciences and Nutrition, 72, 665-669.

Summary

• Review paper outlining the evidence for a link between habitual intake of diverse fruit and veg and increased microbial diversity within the gut, with possible implications for reduced chronic disease.

Evidence underpinning our commitment to drinking plenty of water and minimising sugar-sweetened beverages and artificially sweetened beverages

Armstrong, L. E., Barquera, S., Duhamel, J. F., Hardinsyah, R., Haslam, D., & Lafontan, M. (2012).Recommendations for healthier hydration: addressing the public health issues of obesity and type 2 diabetes. Clinical Obesity, 2, 115-124.

Summary

• A consensus statement from experts in medicine, nutrition, physiology and public health on healthy hydration practices tackling obesity and Type 2 diabetes.

Evidence that non-alcoholic drinks contain more sugar and are more highly processed.

Bauwens, J., Van Opstaele, F., Eggermont, L., Weiland, F., Jaskula?Goiris, B., De Rouck, G., … & De Cooman, L. (2021). Comprehensive analytical and sensory profiling of non-alcoholic beers and their pale lager beer counterparts. Journal of the Institute of Brewing, 127, 385-405.

Summary

• Comprehensive analytical and sensory evaluation of pale lager beers and their non alcoholic counterparts.
• Non-alcoholic beers clearly differ in that they typically contain higher levels of carbohydrates, lower amounts of esters and higher alcohols, different amino acid profiles and higher levels of aldehyde markers.

Evidence underpinning our commitment to time restricted eating.

Wilkinson, M. J., Manoogian, E. N., Zadourian, A., Lo, H., Fakhouri, S., Shoghi, A., … & Taub, P. R. (2020). Ten-hour time-restricted eating reduces weight, blood pressure, and atherogenic lipids in patients with metabolic syndrome. Cell Metabolism, 31, 92-104.

Summary

• Evidence that TRE (10-hr eating window) reduces risk factors for Type 2 diabetes including waist circumference, percent body fat, visceral fat, blood pressure, HbA1c, a measure of blood sugar

Cienfuegos, S., McStay, M., Gabel, K., & Varady, K. A. (2022). Time-restricted eating for the prevention of type 2 diabetes. The Journal of Physiology, 600, 1253-1264.

Summary

• Review outlining the evidence for the effectiveness of TRE on body weight and markers of glycaemic control, both risk factors for Type 2 diabetes

Sutton, E. F., Beyl, R., Early, K. S., Cefalu, W. T., Ravussin, E., & Peterson, C. M. (2018). Early time-restricted feeding improves insulin sensitivity, blood pressure, and oxidative stress even without weight loss in men with prediabetes. Cell Metabolism, 27, 1212-1221.

Summary

• Evidence that TRE can reduce risk factors for Type 2 diabetes, insulin resistance, high blood pressure, and oxidative stress, in individuals with prediabetes.