Watching Carbs: Healthful or Harmful?

Transcription

1 Watching Carbs: Healthful or Harmful? Marjorie Sawicki, MS, RD, LDN Assistant Professor Department of Nutrition & Dietetics, School of Allied Health Professions

2 Carbohydrate in the Diet Carbohydrate comprises most of the calories eaten by people in the world. This has been true for about 10,000 years with the rise of agriculture. The diet of hunter-gatherers before agriculture was lower in carbohydrate, higher in meat (protein & fat). The diet of our near ancestors, the great apes, is largely plant based. So. What diet best matches our genes?

3 Important Source of Energy Depending upon the locality, culture and economic status carbohydrates are a primary source of energy. Carbohydrates comprise 40-80% of the energy consumed by various populations around the world. Reliance upon carbohydrates production allows us to feed the world.

4 Carbohydrate Consumption Country Energy Carbs % energy Starch % energy Sugars % energy South Africa China India Vietnam France UK Chile Canada USA * Australia * Denotes sucrose only

5 Simple Sugars More than Sucrose? Many terms describe simple sugars in surveys Sugars Refined sugar Added sugar Sucrose Sugars minus lactose A standard of terminology is needed for consistency in reporting carbohydrates and its components in food. Often there is no description of what is being reported (39). Food and Agriculture Organization/World Health Organization. Carbohydrates in Human Nutrition. Report of a Joint FAO/WHO Expert Consultation. Rome, April FAO Food and Nutrition Paper 66, 1998.

6 Functions of Carbohydrate Provides energy Affects satiety/gastric emptying Affects blood glucose and insulin regulation Assists in protein glycosylation Affects cholesterol and triglyceride regulation Fermentation in bowel results in: Gas production Short-chain fatty acid production Colon cell function Maintains regularity Affects the large bowel microflora

7 Complex Carbohydrates The term complex carbohydrate first surfaced in the 1977 McGovern report Dietary Goals for the United States. It was an attempt to separate sugars from other carbohydrates, specifically fruits, vegetables and whole grains. Primarily it was used to promote consumption of whole grains whose carbs are primarily starch or the mixture of all polysaccharides. With that definition fruits and vegetables don t fit due to lack of starch.

8 Food Sources of Carbohydrate Food Group Grain ½ cup Fruit ½ cup Dry bean ½ cup Milk 1 cup Vegetable ½ cup Sugar 1 Tbsp Carbs 15 gms 15 gms 15 gms 12 gms 5 gms 15 gms Example

9 USDA Food Guide Pyramid

10 Dr Willett s Food Pyramid

11 Other Dietary Recommendations CVD treatment & prevention National Cholesterol Education Program, Adult Treatment Panel III 10-20% total calories from protein; up to 35% total calories as fat; rest is CHO; at least 45% of total calories Diabetes treatment (American Diabetes Association, American Dietetic Association) 10-20% total calories from protein

12 er CHO & er Fat Diets A diet higher in fat (MUFA: olive oil, canola oil) and lower in carbs may be preferable for insulin resistant syndrome Increased serum TG, decreased HDL-C Obesity, high blood pressure Improved lipid profile Glycemic control Better or at least as good as high carb diet Assumes no weight gain

13 Calories Still Count No matter what the proportion of CHO, protein and fat - caloric intake vs energy expenditure cannot be ignored Variety of food choices important Maintain or achieve a healthy weight Get adequate physical activity

14 Glycemic Index as a Guide? The FAO/WHO recommend the following: GI should be used to compare foods of similar composition within food groups. GI and food composition should be compared when choosing carbohydrate containing foods.

15 Glycemic Index Univ of Sidney Food lists mendosagi/ngilists.htm

16 Glycemic Index Effects Glucose and insulin responses vary Glycemic index may affect insulin sensitivity Long-term, thru hypersecretion of insulin Lipogenesis increased by high glycemic index foods CHO is not homogeneous Amylose (linear) vs amylopectin (branched) Food form: example, pasta vs bread Other components: Fiber: soluble fiber slows gastric emptying Fat: slows gastric emptying

17 Glycemic Index Scale GI foods 55 or less GI Medium GI foods GI GI foods 70 or higher GI

18 Glycemic Load Takes into account both glycemic index and amount of glucose in the consumed food; i.e., serving size Carrots: 5 g glycemic index, about 100% but a 1/2 cup serving of cooked carrots has only 5 grams of CHO, 35 kcals Haagen Dazs Choc Ice Cream: 11 g er glycemic index; 1/2 cup has 22 g CHO, about 11 g glucose, 11 g fructose, 270 kcals

19 Eating by Glycemic Index Foods should not be judged by their GI alone. You might start by including a low GI food in each meal this would lower the GI of the overall meal. Foods with high GI values can help replenish muscle fuel stores after a hard workout they are also helpful in a hypoglycemic event.

20 University of Sidney s Glycemic Index Recommendations Enjoy a wide variety of nutritious foods Regular carbohydrate intake with at least one low GI food at each meal saturated fat fiber foods

21 Pros of Carbohydrate Consumption Provides the brain with a reliable source of glucose for its metabolism. A plant based diet is associated with improved health and lower risks of cardiovascular disease and cancer. Carbs fuel athletic performance and work at higher levels of intensity. Carbs bring along vitamins, minerals and fiber for good health.

22 Comparison of Diets Hunter- Gatherer Carb (Atkins) Fat (Ornish) Mediterranean Diet Protein (19-35%) Mod (18-23%) (<15%) Mod (16-23%) Carb Mod (22-40%) (4-26%) (80%) Mod (50%) Fat Mod (28-47%) (51-78) (<10%) Mod (30%) Sat Fat Moderate Mono Fat Moderate Poly Fat Moderate Moderate Moderate Omega-3 Fat Fiber Fruit/Vegetable Nuts & Seeds Moderate Moderate Salt Moderate Refined Sugars Glycemic Load

23 Aim for the Middle Ground Mediterranean Diet er fat, lower carbohydrate Not as high in fat as Atkins & not as low in carbs Healthy fats: MUFA (olive oil, canola, nut oils) Dispells the fear of fat Promotes other components of diet as important Emphasis on heart healthy fats and whole grains, whole foods Can be paired with a lower glycemic index eating plan

24