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LOW CARBOHYDRATE DIETS IN DIABETES

Medical nutritional therapy is a vital part of preventing diabetes and managing it1. It aims to promote the enjoyment of a variety of nutrient dense foods, in appropriate portion sizes, in order to:

  • Achieve glycaemic, blood pressure and lipid goals;
  • Achieve and maintain body weight goals and
  • Delay or prevent complications associated with diabetes1.

Nutritional guidelines generally focus on a carbohydrate-based [≥ 45% of Total Energy Intake (TEI)], moderate-protein (20% of TEI), low-fat (≤30% of TEI) diet. There are numerous benefits associated with this way of eating but adherence is often an issue2, 3, 4. The use of low-carbohydrate diets (LCD) has attracted a great deal of attention over the last few years. This is due to reports that they result in greater weight loss – as well as more improvements in biochemical markers and reductions in medication usage – than conventional diets. This has resulted in the suggestion that LCDs should be used to help manage diabetes3.

WHAT DOES THE RESEARCH SAY?

The American Diabetes Association (ADA) states that carbohydrates are the primary nutrient, affecting glycaemic control. The rationale is that reducing your carbohydrate intake should improve your glycaemic control2,4,5. This, however, is not always the case and studies give us contradicting evidence.

Glycaemic control

One review of trials – conducted between 1980 and 2006 – looked at 12 studies, involving a total of 251 participants. Subjects were divided into two groups: An intervention group, with carbohydrates making up 29% of its TEI (range: 4 to 45%), and a control group, with carbohydrates making up 55% of its TEI (range: 40 to 70%)6. Authors found a significantly greater reduction in the intervention group’s fasting blood glucose and HbA1C, compared to the control group’s6. Lower levels of carbohydrates resulted in greater reductions in both measures6. Reviewers of this article noted there was a lack of information regarding review methods and study quality, which could have affected the reliability the results7. In another review, that looked at studies – published from 2001 to 2015 – on adult diabetics, researchers found there was a significant reduction in Glycated Haemoglobin across all studies8. The significance of the decrease tended to depend on the amount of carbohydrates consumed per day. The reduction in HbA1C ranged from 0.7 to 0.9%, with a daily carbohydrate intake of 75 to 120g8. The greatest reduction was 2.2%, with 30g of carbohydrates per day8. Fasting blood glucose showed an immediate response and decreased from 11.7 mmol/l to 7.0 mmol/l, which necessitated an immediate reduction in medication8. Authors also reported that 52% of subjects consuming 14 % of their TEI from carbohydrates, reduced their medication. This compared to 21% of those following a diet in which carbohydrates made up 53% of their TEI8.

Another paper reviewing nine meta-analyses, identified 12 studies on diabetic adults – all with an intervention period of 4 or more weeks4. Authors found that only 1 of the 12 studies reported a significant reduction in HbA1C concentration following the implementation of a low-carbohydrate Mediterranean (LCM) diet9. They also found none of the studies indicated any significant differences in the fasting blood glucose of those on LCDs and those on other diets4. A meta-analysis by Naude et al (2014,) that compared 19 trials with a total of 3209 participants, concluded that groups on low-carbohydrate diets and groups on balanced diets showed similar reductions in their average HbA1c after 3 to 6 months10. At 1 to 2 years, the average HbA1c change was more variable. However, when combining data from all the trials, the two diets showed similar changes in HbA1c in diabetic subjects at 3 to 6 months and at 1 to 2 years10. A similar result was found in terms of fasting blood glucose at 3 to 6 months and at 1 to 2 years, on both diets10.

There was a significant decrease in the percentage HbA1c (−0.12%) in subjects who consumed a LCD14. But this review also concluded that low-GI (−0.14%), high-protein (−0.18%) and Mediterranean (−0.47%) diets were just as – if not more – effective in lowering HbA1c14. In one review, low-fat diets (fat <30% of TEI) were compared to low-carbohydrate diets (<50 g per day). Authors found there was no significant difference between treatment groups, in terms of changes in fasting blood glucose (eight trials), insulin (six trials) and HbA1c (four trials) in overweight and obese patients.

THE BOTTOM LINE

Glycaemic control: There is evidence both for and against the use of low carbohydrate diets as a way to improve HbA1C and fasting blood glucose in individuals living with diabetes.

Weight loss: As seen with glycaemic control, there are studies both for and against the use of LCD for weight loss. The optimal macronutrient intake to support weight loss has not been established. The literature does not support one particular nutrition therapy approach over another but rather a spectrum of eating patterns that result in reduced energy intake2.

Lipid parameters: Research shows that low-carbohydrate diets resulted in an improvement in many of the lipid parameters with best results seen in HDL and triglyceride levels. However, the other diets were just as effective, particularity in LDL and total cholesterol. There is good evidence that replacing SFA with PUFA or MUFA, has a beneficial effect on total and LDL cholesterol levels.

WHERE DOES FUTURELIFE® FIT IN?

At FUTURELIFE® we have a range of products that can fit into a healthy, balanced diet. Many of them are high in fibre and protein, low GI. The following products are suitable for those living with Diabetes:

  • FUTURELIFE® HIGH PROTEIN Smart food™
  • FUTURELIFE® ZERO Smart food™
  • FUTURELIFE® Smart food™
  • FUTURELIFE® High Protein LITE SmartBar
  • FUTURELIFE® Smart Drink™
  • FUTURELIFE® Smart Bread™
  • FUTURELIFE® Bran Flakes with Probiotic Sachets

FUTURELIFE® HIGH PROTEIN Smart food™ could be considered to form part of the low carbohydrate diet approach. FUTURELIFE® HIGH PROTEIN Smart food™ is a high protein convenient meal for an on the go meal or snack. For exact nutritionals and further information on the product visit www.futurelife.co.za

REFERENCES

  1. Journal of Endocrinology, Metabolism and Diabetes of South Africa (2017). SEMDSA 2017 Guidelines for the Management of Type 2 diabetes mellitus. Available at: https://www.semdsa.org.za/images/647-4385-1-PB.pdf (Accessed 26th July 2017)
  2. Diabetes Care (2010). A Position Statement of the American Diabetes Association. Available at: http://care.diabetesjournals.org/content/31/Supplement_1/S61.long (Accessed 26th July 2017)
  3. PubMed. (2008). Dietary carbohydrate restriction in type 2 diabetes mellitus and metabolic syndrome: time for a critical appraisal. Available at: https://www.ncbi.nlm.nih.gov/pubmed/18397522 (Accessed 30th August 2017)
  4. Wiley Online Library. (2016) A critical review of low-carbohydrate diets in people with Type 2 diabetes. Available at: http://onlinelibrary.wiley.com/doi/10.1111/dme.12964/full (Accessed 30th August 2017)
  5. Nutrition (2015). Dietary carbohydrate restriction as the first approach in diabetes management: Critical review and evidence base. Available at: http://www.nutritionjrnl.com/article/S0899-9007(14)00332-3/fulltext (Accessed 31st August 2017)
  6. Pubmed. (2004) Restricted-carbohydrate diets in patients with type 2 diabetes: a meta-analysis Available at: https://www.ncbi.nlm.nih.gov/pubmed/18155993 (Accessed 31st August 2017)
  7. PubMed Health. Database of Abstracts of Reviews of Effects (DARE). (2008) Restricted-carbohydrate diets in patients with type 2 diabetes: a meta-analysis. Available at: https://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0026824/ (Accessed 31st August 2017)
  8. Proceedings of the Nutrition Society (2017). Should a Low Carbohydrate Diet be recommended for Diabetes Management? Available at: https://www.cambridge.org/core/services/aop-cambridge-core/content/view/E5C2E3059142A9C4D5C2A73EB1DB8F09/S0029665117000192a.pdf/div-class-title-should-a-low-carbohydrate-diet-be-recommended-for-diabetes-management-div.pdf (Accessed 31 July 2017)
  9. Wiley Online Library (2010). A low carbohydrate Mediterranean diet improves cardiovascular risk factors and diabetes control among overweight patients with type 2 diabetes mellitus: a 1-year prospective randomized intervention study. Available at: http://onlinelibrary.wiley.com/doi/10.1111/j.1463-1326.2009.01151.x/abstract (Accessed 31 July 2017)
  10. PubMed (2014). Low carbohydrate versus isoenergetic balanced diets for reducing weight and cardiovascular risk: a systematic review and meta-analysis. Available at: https://www.ncbi.nlm.nih.gov/pubmed/25007189 (Accessed 30 August 2017)
  11. PubMed health (2013). Very-low-carbohydrate ketogenic diet v low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. Available at: https://www.ncbi.nlm.nih.gov/pubmed/23651522 (Accessed 1st September 2017)
  12. Nutrition Recommendations and Interventions for Diabetes: A position statement of the American Diabetes Association (2008) Available at: http://care.diabetesjournals.org/content/31/Supplement_1/S61.full (Accessed: January 2017)
  13. Nutrition authority (2017). 23 Studies on Low-Carb and Low-Fat Diets – Time to Retire The Fad. Available at: http://www.healthline.com/nutrition/23-studies-on-low-carb-and-low-fat-diets#section2 (Accessed: June 2017)
  14. American Journal of Clinical nutrition. (2013). Systematic review and meta-analysis of different dietary approaches to the management of type 2 diabetes. Available at: http://ajcn.nutrition.org/content/97/3/505.full.pdf+html. (Accessed 1st September 2017)
  15. NCBI (2014). The amount and type of dietary fat on cardiometabolic risk factors and risk of developing type 2 diabetes, cardiovascular diseases, and cancer: a systematic review. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4095759/ (Accessed 31 July 2017)
  16. Effects of Low-Carbohydrate Diets Versus Low-Fat Diets on Metabolic Risk Factors: A Meta-Analysis of Randomized Controlled Clinical Trials. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3530364/ (Accessed September 2017)

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