metabolism of carbohydrates: implications for health
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Metabolism of Carbohydrates: Implications for Health
Janine Higgins, PhDUniversity of Colorado Denver
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 waterand 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
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 waterand 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”
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 waterand 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.”
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 waterand 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
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 waterand 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”
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 waterand 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
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 waterand 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”
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 waterand 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
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
waste out
food in
xx x x
x
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x
x
x x^^x ^
x
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Rapidly Digested Starch Slowly Digested Starch
Resistant Starchx
^ Glucose
Fructose
Lactate
TG
CO2
Glucose (50%)
Lactate (25%)TG
Glycogen (15%)
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
Daly et al (2000) Am J Clin Nutr 71: 1516.
Higher CHO ox’n after sucrose meal than starch meal
FROM SUCROSE: Higher fructose ox’n, delayed glucose ox’n
N=722-68 yo, healthyCrossover design
Fructose Increases CHO Oxidation
Brown et al (2000) Am J Physiol 294: R730.
Fructose caused higher CHO ox’nNo change in TEE Lower fat oxidation
Higher CHO ox’n after sucrose meal than starch meal
FROM SUCROSE: Higher fructose ox’n, delayed glucose ox’n
Fructose Increases CHO Oxidation
Sucrose Decreases Fat Oxidation
Daly et al (2000) Am J Clin Nutr 71: 1516.N=722-68 yo, healthyCrossover design
Total CHO Intake Is Associated with Lower BMI
Gaesser, J Am Diet Assoc. (2007) 107:1768
NHSII 26 23N=90,655
HPFS 26.1 24.8N=39,926
Sugar Intake Is Associated with Higher Adiposity
Davis et al, Am J Clin Nutr. (2007) 86:1331
N=12010-17 yo, overweight24 h diet recalls
• Total sugar (g/d) positivelycorrelated with body mass index (BMI; in kg/m2), BMI zscores, 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.
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
Sucrose impairs insulin action at liver not peripheral tissue – Rat study
Storlien et al (1988) Am J Clin Nutr 47: 420Rat study
No significant change in glucose uptake in isolated muscle or adipose tissues.
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
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
Fructose Increases Circulating TG
Stanhope et al (2009) J Clinical Invest 119: 1322.N=7Overweight/obese postmenopausal25% of daily energy from sweetened drinks
Fructose Increases Blood Pressure in Healthy Adults
Brown et al (2000) Am J Physiol 294: R730.
Fructose causes increased systolic and diastolic BP - due to increased cardiac output, no change in peripheral vasodilation
N=1521-33 yo, healthyCrossover design
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.
• Limit simple sugars? • How about focusing on limiting total
caloric intake???
Thanks to:Troy DonahooPaul MacLeanIan BrownCCTSI Nutrition
Core
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