Metabolism of Carbohydrates: Implications for Health

1. Metabolism of Carbohydrates: Implications for Health Janine Higgins, PhD University of Colorado Denver

2. Dietary Recommendations Enjoy a wide variety of nutritious foods • Eat plenty of vegetables, legumes and fruits • Eat plenty of cereals, preferably wholegrain • Include lean meat, fish, poultry and/or alternatives • Include milks, yoghurts, cheeses – choose low fat • Drink plenty of water and take care to: • Limit saturated fat and moderate total fat intake • Choose foods low in salt • Limit your alcohol intake if you choose to drink • Consume only moderate amounts of sugars and foods containing added sugars

3. Dietary Recommendations Enjoy a wide variety of nutritious foods • Eat plenty of vegetables, legumes and fruits • Eat plenty of cereals, preferably wholegrain • Include lean meat, fish, poultry and/or alternatives • Include milks, yoghurts, cheeses • Drink plenty of water and take care to: • Limit saturated fat and moderate total fat intake • Choose foods low in salt • Limit your alcohol intake if you choose to drink • Consume only moderate amounts of sugars and foods containing added sugars Cochrane Database Syst Rev. 2011 Jul 6;(7):CD002137. Reduced or modified dietary fat for preventing cardiovascular disease. Hooper L, Summerbell CD, et al. “Small but important reduction in cardiovascular risk for reduction of saturated fat, but not reduction of total fat, in longer trials”

4. Dietary Recommendations Enjoy a wide variety of nutritious foods • Eat plenty of vegetables, legumes and fruits • Eat plenty of cereals, preferably wholegrain • Include lean meat, fish, poultry and/or alternatives • Include milks, yoghurts, cheeses • Drink plenty of water and take care to: • Limit saturated fat and moderate total fat intake • Choose foods low in salt • Limit your alcohol intake if you choose to drink • Consume only moderate amounts of sugars and foods containing added sugars J Int Med Res. 2010 Mar-Apr;38:318-85. Nutritional profiles in a public health perspective: a critical review. Foltran F, Verduci E, et al. “Evidence linking a reduced fat intake with cardiovascular mortality and obesity is generally non-significant.”

5. Dietary Recommendations Enjoy a wide variety of nutritious foods • Eat plenty of vegetables, legumes and fruits • Eat plenty of cereals, preferably wholegrain • Include lean meat, fish, poultry and/or alternatives • Include milks, yoghurts, cheeses • Drink plenty of water and take care to: • Limit saturated fat and moderate total fat intake • Choose foods low in salt • Limit your alcohol intake if you choose to drink • Consume only moderate amounts of sugars and foods containing added sugars

6. Dietary Recommendations Enjoy a wide variety of nutritious foods • Eat plenty of vegetables, legumes and fruits • Eat plenty of cereals, preferably wholegrain • Include lean meat, fish, poultry and/or alternatives • Include milks, yoghurts, cheeses • Drink plenty of water and take care to: • Limit saturated fat and moderate total fat intake • Choose foods low in salt • Limit your alcohol intake if you choose to drink • Consume only moderate amounts of sugars and foods containing added sugars Cochrane Database Syst Rev. 2011 Jul 6;(7). Reduced dietary salt for the prevention of cardiovascular disease. Taylor, Ashton, et al. 665 deaths in some 6,250 participants: “No strong evidence of benefit of salt restriction on all cause or cardiovascular mortality in normal or hypertensive patients”

7. Dietary Recommendations Enjoy a wide variety of nutritious foods • Eat plenty of vegetables, legumes and fruits • Eat plenty of cereals, preferably wholegrain • Include lean meat, fish, poultry and/or alternatives • Include milks, yoghurts, cheeses • Drink plenty of water and take care to: • Limit saturated fat and moderate total fat intake • Choose foods low in salt • Limit your alcohol intake if you choose to drink • Consume only moderate amounts of sugars and foods containing added sugars

8. Dietary Recommendations Enjoy a wide variety of nutritious foods • Eat plenty of vegetables, legumes and fruits • Eat plenty of cereals, preferably wholegrain • Include lean meat, fish, poultry and/or alternatives • Include milks, yoghurts, cheeses • Drink plenty of water and take care to: • Limit saturated fat and moderate total fat intake • Choose foods low in salt • Limit your alcohol intake if you choose to drink Av. Aus intake = 9.8L/y or 188mL/wk = < 2 glasses wine/wk • Consume only moderate amounts of sugars and foods containing added sugars BMJ. 2011 Feb 22;342:d671. doi: 10.1136/bmj.d671. Association of alcohol consumption with selected cardiovascular disease outcomes: a systematic review and meta-analysis. Ronksley PE, Brien SE, et al. “Moderate alcohol consumption is associated with a reduced risk of multiple cardiovascular outcomes. Dose-response analysis revealed that the lowest risk of coronary heart disease mortality occurred with 1-2 drinks a day”

9. Dietary Recommendations Enjoy a wide variety of nutritious foods • Eat plenty of vegetables, legumes and fruits • Eat plenty of cereals, preferably wholegrain • Include lean meat, fish, poultry and/or alternatives • Include milks, yoghurts, cheeses • Drink plenty of water and take care to: • Limit saturated fat and moderate total fat intake • Choose foods low in salt • Limit your alcohol intake if you choose to drink • Consume only moderate amounts of sugars and foods containing added sugars

10. Added/Simple Sugars • Glucose and fructose (sucrose) most commonly consumed - In USA, adults consume ~23 tsp (120g) of added sugar/d; from soft drinks, juice, desserts (pastries, pies), and lollies - 9% of energy from fructose, 10% from sucrose (total 19%) - In UK, ~16% of total energy from sucrose • Glucose and fructose are metabolized differently and have different metabolic effects

11. food in Rapidly Digested Starch Slowly Digested Starch Resistant Starch Glucose x Fructose ^ ^ x x x x ^ x ^ Lactate x ^ ^ x ^ ^ ^ x x ^ x x CO2 TG Glucose (50%) TG Lactate (25%) Glycogen (15%) waste out

12. Fructose vs Glucose • Liver: • Increases gluconeogenesis • Increases de novo lipogenesis • Causes insulin resistance • Increases intracellular lipid • Whole Body: • Increases TG production • Decreases TG clearance • Decreases plasma FFA – lower adipocyte lipolysis

13. Fructose Increases CHO Oxidation Higher CHO ox’n after sucrose meal than starch meal FROM SUCROSE: Higher fructose ox’n, delayed glucose ox’n N=7 22-68 yo, healthy Crossover design Daly et al (2000) Am J ClinNutr 71: 1516.

14. Fructose Increases CHO Oxidation Higher CHO ox’n after sucrose meal than starch meal FROM SUCROSE: Higher fructose ox’n, delayed glucose ox’n Fructose caused higher CHO ox’n No change in TEE Lower fat oxidation Brown et al (2000) Am J Physiol 294: R730.

15. Sucrose Decreases Fat Oxidation N=7 22-68 yo, healthy Crossover design Daly et al (2000) Am J ClinNutr 71: 1516.

16. Total CHO Intake Is Associated with Lower BMI NHSII 26 23 N=90,655 HPFS 26.1 24.8 N=39,926 Gaesser, J Am Diet Assoc. (2007) 107:1768

17. Sugar Intake Is Associated with Higher Adiposity • Total sugar (g/d) positively • correlated with body mass index (BMI; in kg/m2), BMI z • scores, and total fat mass (r 0.20, r 0.22, and r 21) • Total sugar (g/d)negatively correlated with SI (r0.29) • Dietary fiber, glycemic index, and glycemic load were not correlated with adiposity or insulin dynamics before or after control for covariates. N=120 10-17 yo, overweight 24 h diet recalls Davis et al, Am J ClinNutr. (2007) 86:1331

18. Large epidemiological studies • Multiple large studies – generally no association between high fructose corn syrup intake and body weight or obesity • Difficult to interpret data • ↑ intake of artificial sweeteners is in obese; ↑ intake of sucrose is in the most lean individuals • No relationship between regular soft drink intake and obesity or BMI; positive association of diet soft drink intake with obesity and BMI

19. Sucrose impairs insulin action at liver not peripheral tissue – Rat study No significant change in glucose uptake in isolated muscle or adipose tissues. Rat study Storlien et al (1988) Am J Clin Nutr 47: 420

20. Rats 2 • Relative to chow, both high sucrose and high cornstarch diet: • decreased glucose uptake in muscle • increased intramuscular triglyceride • increased visceral fat with no change in total body weight • increased fasting insulin Kim et al, Am J Physiol. (1999) 276:R665

21. Human Data • High fructose ingestion for one or 10 weeks caused insulin resistance vs glucose • Moderate fructose intake for 4 wk increased TG but did not impair insulin action • Fructose and sucrose have similar effects

22. Fructose Increases Circulating TG N=7 Overweight/obese postmenopausal 25% of daily energy from sweetened drinks Stanhope et al (2009) J Clinical Invest 119: 1322.

23. Fructose Increases Blood Pressure in Healthy Adults Fructose causes increased systolic and diastolic BP - due to increased cardiac output, no change in peripheral vasodilation N=15 21-33 yo, healthy Crossover design Brown et al (2000) Am J Physiol 294: R730.

24. Conclusions • Simple sugars are absorbed and metabolized differently from starches • To impact health outcomes need to consider CHO quality NOT just quantity • quality is more than simple vs complex • Fructose has several negative impacts on metabolism vs glucose or starch • Large epidemiological studies cannot provide meaningful data to demonstrate benefits/risks of simple sugar consumption.

25. Limit simple sugars? • How about focusing on limiting total caloric intake???

26. Thanks to: Troy Donahoo Paul MacLean Ian Brown CCTSI Nutrition Core