Carbs: The Staff of Life, or The Stuff of Death? Ed Cox, M.D.

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1 Carbs: The Staff of Life, or The Stuff of Death? Ed Cox, M.D.

2 Pyramid, or Paleo?

3 Carbs defined Carbohydrates (abbrev. CHO) = saccharides Saccharide from Greek for sugar, denoting sweetness Technical terms in chemistry

4 Carbs defined Compounds of carbon, oxygen and hydrogen in the ratio of 1:1:2, For example, C6O6H12 (glucose) Usually 5 or 6 carbons Circles back on itself to form a ring, like a link in a chain

5 Carbs defined The simplest unit is a monosaccharide, such as glucose (link) Others are polymers (chains) of monosaccharides The polymers are disaccharides (2 units), oligosaccharides (3-9), and polysaccharides (>9) Monosaccharides and disaccharides are, mostly, sugars Polysaccharides from plants are starches or fiber

6 Fat phobia: Carbs embraced In the 1970s, we were told that fats were making us fat and killing us As long as we restricted our fats, we could eat as many carbs as we wanted and be healthy The USDA Food Pyramid in 1990 codified the idea that carbs were fine Foundation: 11 servings a day The public dutifully complied The result: Epidemic of obesity and diabetes

7 Pushback: Carbs shunned! Unrestricted carbs are not the answer; they are a problem! Dr. Atkins (and others) told us to eat as much fat and protein as we wanted As long as we avoided the carbs, we would lose weight and feel great As we entered the new millennium, we left behind fat phobia, only to enter the era of carb phobia! Gluten phobia arrived on the scene, piling on to the concept that carbs were bad, especially if they came from wheat Can t eat fat, can t eat carbs; what can we eat??

8 Carbs are diverse The problem with avoiding carbs is throwing out the baby with the bath water The term carbs covers many different food sources that vary dramatically in their basic nature, as well as in how they are prepared The term carbs is nearly meaningless, except as a concept of chemistry The right carbs, as we shall see, are very good for us, while the wrong ones are harmful

9 Retirement for the term carbs Almost meaningless term for discussing diet No specificity Covers distinct and dissimilar categories: sugars, starches, fiber Carries enormous baggage from its use in fad diets and lay publications Not further used in this discussion, except as necessary in reference to studies and reports

10 Monosaccharides Common monosaccharides in nutrition are glucose (dextrose), fructose and galactose Glucose: grape sugar Fructose: found in many plants, in cane sugar Galactose: found in milk sugar

11 Monosaccharides Monosaccharides can exist in a closed form and an open form Closed form (link) predominates and is the form that is polymerized to make di-, oligo- and polysaccharides (chains)

12 Monosaccharides Glucose is the most important monosaccharide, as it is the common transport and storage saccharide Starch broken down to glucose for absorption in small intestine Glucose is polymerized into glycogen in the liver and muscles for storage Released from storage as the body calls for energy

13 Disaccharides Disaccharides consist of two monosaccharides Generally perceived as sweet tasting Sweet monosaccharides and disaccharides are known as sugars Common disaccharides Sucrose: Glu-Fru cane sugar Lactose: Gal-Glu milk sugar Maltose: Glu-Glu released in breakdown of starch

14 Digestion of disaccharides Lactase is a special enzyme for splitting lactose (milk sugar) into glucose and galactose Sucrase splits sucrose (table sugar) into glucose and fructose Lactase deficiency is common in some populations; associated with GI ill effects after consuming milk products Monosaccharides and maltose are absorbed directly by the small intestinal lining, including those from amylase digestion of starches

15 Oligosaccharides Oligosaccharides are short polymers of about 3 to 9 monosaccharides Important ones come from plants or fungi FOS (fructose OSs) from vegetables, GOS (galactose OSs), MOS (mannan OSs) from yeast Those that are non-digestible and non-absorbable play important roles as nutrients for intestinal microflora Concept of prebiotics substances that keep our intestinal tract micro-organisms in the right balance Some may play a role in irritable bowel disease, gluten intolerance

16 Polysaccharides Polysaccharides are long chain polymers of monosaccharides (generally > 10 units) Nutritionally important PS are polymers of glucose Animal: Glycogen, the storage PS Plants: Starch (amylose and amylopectin) and cellulose

17 Cellulose Most abundant organic polymer on Earth Main structural component of plants 40-50% of wood, 45% of hemp, 90% of cotton Long straight chains of glucose which are cross-linked to adjacent chains, in a very dense, strong network Digestible only by ruminants, termites

18 Starch polysaccharides Starches are the PS found in fruits of plants: Amylose and amylopectin Amylopectin (70-80% of starch) is highly branched and is digested rapidly, into maltose and glucose Amylose (20-30% of starch) is an unbranched helix, digested slowly, into maltose and oligosaccharides Resistant starch Different strains of plants have different proportions of amylose and amylopectin For example, high-amylose rice has more amylose relative to amylopectin

rapidly High glycemic index rapid rise in blood glucose and insulin Amylose (20-30% of starch) is digested slowly Low

19 Digestion of polysaccharides Amylase (lower image) is the enzyme that cleaves amylose and amylopectin into mono-, di- and oligosaccharides Amylase is secreted in saliva and in pancreatic juices Amylopectin (70-80% of starch) is digested rapidly High glycemic index rapid rise in blood glucose and insulin Amylose (20-30% of starch) is digested slowly Low glycemic index more slowly absorbed, with slower rise in blood glucose and insulin Sugars released are absorbed in small intestine

20 Plant foods provide saccharides Grains (AKA cereals) Tubers Stalks Pulses (AKA beans, legumes) Fruits Vegetables Nuts and seeds

22 Glucose and insulin Insulin is the master control molecule to maintain constant blood sugar level Secreted by pancreas islet cells Signals liver, muscles and fat cells to remove glucose from blood

23 24 hour glucose and insulin

24 Hyperglycemia Refers to blood glucose values that rise substantially above those in healthy individuals after a meal, or remain elevated after digestion is complete Hyperglycemia is the defining characteristic of diabetes mellitus

25 Diabetes mellitus Type I diabetes is complete failure of insulin secretion by the pancreatic islet cells; earlier referred to as juvenile diabetes Type II diabetes is insufficient insulin secretion relative to the metabolic need for it Major component of metabolic syndrome, or syndrome X Associated with obesity, hypertension Associated with lipid abnormalities, increased risk of CHD, CVD Earlier referred to as adult-onset diabetes

26 Quantifying hyperglycemia Long known that the persistent blood sugar elevation is associated with dramatic increase in cardiovascular diseases Suspected that the elevated blood glucose itself was strong contributor to vascular disease Further suspected that elevated blood glucose levels not high enough to make a diagnosis of diabetes could be harmful Different carbohydrates produce different blood glucose profiles after their consumption Needed a measure for quantifying the amplitude and duration of glucose elevation

27 Sugary drinks and CHD Fung et al Am J Clin Nutrition 2009

28 Sugary drinks and CHD - NHS Nurses Health Study 88,520 women ages No pre-existing CHD, stroke, CVD, or diabetes Detailed, repeated dietary histories Detailed accounting for confounding variables Follow-up of 24 years, during which 3,105 cases were observed (MI or death from CVD)

29 Sugary drinks and CHD - NHS

30 Sugary drinks and CHD - NHS

31 Sugary drinks and CHD - NHS

32 Sugary drinks and CHD NHS Artificial sweeteners

33 Sugary drinks and CHD Woman drinking two or more SSB (sugar-sweetened beverages) a day were at nearly double risk of heart attack or cardiac death Risk remained 39% higher even after accounting for other contributing factors Fruit drinks were as bad as colas Even one SSB was associated with a 27% increased risk Artificial sweeteners trended toward increased risk at 2 or more servings a day but not statistically significant

34 Grains (cereals) Cereal grains are grown in greater quantity and provide more food energy worldwide than any other crop - Wikipedia Corn, rice and wheat are the leading types, at 1016, 745, and 713 million metric tonnes of production annually Corn is mostly used for animal feed, so rice and wheat are the main grains used for human consumption

Grains are fruits Fruit in this context refers to the part of a plant responsible for reproduction Endosperm is the starch in cereals that provides fuel as a plant germinates, before

35 Grains are fruits Fruit in this context refers to the part of a plant responsible for reproduction Endosperm is the starch in cereals that provides fuel as a plant germinates, before it can gather energy through photosynthesis The fruit is the part that is readily used for animal nutrition Grinding, cooking, etc. partially disrupt the starch to make it more digestible

36 Grain use history Humans were hunter-gathers until civilization brought agriculture Planting & harvesting grains gave more certainty and used less time & effort Freed up labor for construction, etc. Refining wheat to remove germ and bran was developed BCE, but was so labor intensive that only wealthy families could afford it White baked goods were a status symbol Industrial revolution brought white flour to the masses White flour foods became dominant Whole grain cereals and baked goods were off the table We have come full circle: whole grains are back among the cognoscenti

37 What is whole grain? Grain Small, hard, dried seeds, with or without their attached hull or fruit layers, harvested for human consumption Cereals and pulses (legumes, beans ) Whole In contrast to refined grains, where the starchy endosperm is used exclusively after separation from the germ and bran May refer to grinding and using the entire grain, or separating the components and putting them back together in the end product Is the whole greater than the sum of its parts?

38 Examples of whole grain

39 Whole grain: + and Advantages Fiber from bran improves blood cholesterol profile, digestive regularity Vitamins, protein & fat from germ Phytosterols, other possible goodness Slows absorption of carbs; lowers glycemic index Disadvantages Goes rancid sooner; shorter shelf life? less digestible (bloating, abdominal cramps)

40 Whole grain: legal definition Each country has its own definition of what the content must be to be labeled whole grain In Canada, product may have 70% of germ removed and still be labeled WG 100% whole grain means just that

41 Breakfast cereal: WG vs. refined Liu et al Am J Clin Nutr ,190 males Physicians Health Study

42 WG cereal & mortality: PHS 86,190 male physicians age yr follow-up 3,114 deaths (1,381 due to CVD) Self-administered food frequency questionaire Accounting for smoking, personal health history, BMI, smoking, alcohol, exercise, MVI use, cholesterol, hypertension

44 Total mortality by cereal intake

45 Total mortality: whole vs. refined

47 Breakfast cereal: WG vs. refined Male physicians: Those who ate WG cereal daily had 29% lower CHD mortality and 17% lower overall mortality than those rarely eating WG Those who ate refined cereal daily had the same CHD mortality as those rarely eating refined Results fully adjusted for covariates (age, smoking, alcohol, physical activity, BMI, DM, HTN, cholesterol, MVI)

48 NIH-AARP Whole Grain & Mortality

49 NIH-AARP WG & Mortality Subjects: 367,442 (44% female, yrs) Followup: 14 yrs ( ) Deaths: 11,283 CVD; 19,043 Ca; 3,796 respiratory; 371 diabetes; 922 infection; 5,223 other (46,067 total, 12.5%) Food frequency questionaire: 124 items calibrated by 24 hour food recall Covariates: Age, sex, BMI, physical activity, cigarette smoking, education, marital status, alcohol intake, hormone replacement, consumption of red meat, fruits, vegetables

50 NIH-AARP WG & Mortality One serving of whole grain defined as 1 oz. (28 gm) Average intake from quintile 1 to quintile 5 was 0.13, 0.30, 0.47, 0.69 and 1.20 servings per day, respectively

51 NIH-AARP WG & Mortality: Risk factors Quintile 1 (lowest WG) Quintile 5 (highest WG) Physical activity, vigorous or moderate 41% 55% Current smoking 21% 8% Obesity 23% 17% Alcohol 33 g/d 9 g/d Red meat 3.1 servings/d 1.7 servings/d Those who consume more WG exercise more, consume less red meat, smoke less, and have less obesity, all associated with lower mortality

52 NIH-AARP WG & Mortality Unadjusted Adjusted Relative risk % change Relative risk % change All causes Cardiovascular Cancer Diabetes * Respiratory * Infection * Other * Mortality for quintile 5 (highest) vs. quintile 1 (lowest) level of whole grain consumption P<0.0001, except * 0.02<p<0.0009

53 NIH-AARP WG & Mortality Relative risk % Change p All causes Cardiovascular Cancer Diabetes Respiratory Infection Other Mortality for quintile 5 (highest) vs. quintile 1 (lowest) level of whole grain consumption after accounting for cereal fiber

54 NIH-AARP WG & Mortality: Conclusions Whole grain intake is strongly inversely associated with mortality: all causes, cardiovascular disease, cancer, diabetes, respiratory disease, infection and other Association attenuated but not abolished - after accounting for better lifestyle factors correlated with WG consumption: fewer smokers, greater physical activity, more desirable BMI, less red meat consumption

55 NIH-AARP WG & Mortality: Conclusions Whole grain intake association with mortality is markedly attenuated after adjusting for quantity of cereal fiber (except for diabetes) This finding suggests that the mechanism of the beneficial effect of WG intake on mortality is mainly by way of its fiber content (except for diabetes)

56 NHS-HPFS WG & Mortality

57 NHS-HPFS WG & Mortality Subjects Years F/U Deaths Nurses Health Study 74, ,106 Health Professionals Followup Study 43, ,815 Food frequency questionaire Intake of WG according to dry weight Serving = 1 oz = 28 g Covariates: Medical history, BMI, lifestyle (smoking, physical activity), alcohol, alternative healthy eating index

58 NHS-HPFS WG & Mortality: Risk Factors NHS HPFS Quintile 1 (lower WG) Quintile 5 (higher WG) Quintile 1 (lower WG) Quintile 5 (higher WG) Whole grain (g/d) Smoking % Alcohol (g/d) Physical activity (MET-hr/wk) Alternative Healthy Eating Index Those who consume higher amounts of WG are less likely to smoke cigarettes, exercise more, eat healthier foods and consume less alcohol

59 NHS-HPFS WG & Mortality Results NHS HPFS Pooled All cause Cardiovascular Cancer All cause * 0.91 Cardiovascular Cancer 0.99* 0.95* 0.97* Unadjusted Adjusted Mortality relative risk for quintile 5 (highest WG) vs. quintile 1 (lowest WG) P<0.002 except * p>0.05

60 NHS-HPFS WG & Mortality: Bran and germ Analysis for cardiovascular death in relation to total bran intake and total germ intake No relationship between total germ intake and CVD mortality Relative risk for CVD mortality was 0.80 for quintile 5 (highest) vs. quintile 1 (lowest) of total bran consumption in NHS and HPFS, p<0.001

61 NHS-HPFS WG & Mortality: Conclusions There is a significant inverse relationship between amount of whole grains consumed and mortality, especially cardiovascular disease mortality No relation was found between cancer mortality and WG consumption level after adjusting for risk factors (for example, cigarette smoking) Bran, but not germ, consumption level was also inversely related to cardiovascular mortality

62 WG & Mortality Meta-analysis BMJ 2016; 353:i2716

63 WG & Mortality Meta-analysis Studies: 45 cohorts 20 EU, 16 US, 9 Asia Subjects: 245, ,253 Events: 100,726 deaths; 34,346 cancer cases, 26,243 CVD cases, 7,068 CHD cases, 2,337 CVA cases

67 Glycemic index and health Type 2 diabetes (T2DM) and metabolic syndrome (MetS) are characterized by elevated blood glucose (BG) and, at least initially, elevated insulin Foods carbohydrates in particular that cause higher elevation of BG and insulin may exacerbate T2DM and MetS So, how about identifying foods that raise the blood glucose more or less than a standard amount of glucose Eat less of the former, more of the latter

68 Glycemic index concept Developed by David Jenkins, M.D., Ph.D. (Nutrition), at University of Toronto, in early 1980s GI defined as the ratio of two areas under the glucose vs. time curve above the baseline glucose level: 1) specified amount of test CHO (usually 50 g); 2) same amount of glucose Used to test a large variety of CHO foods in healthy subjects to determine their GI Used to correlate the GI of individual diets with health outcomes, such as chronic diseases like diabetes and CHD

69 Post-meal glucose and AUC Baseline 4.5 mmol / L (80 mg/dl) AUC (area under the curve) is measured as a standard for comparison with other foods After 50 g of oral glucose: AUC for glucose here is 150 mmol/l-min Blood glucose expressed as mmol/l (mg/dl) Peaks about 3.5 (63) above baseline at 30 min Returns gradually to baseline at 100 min Similar to oral glucose tolerance test (GTT) Reflects the balance between glucose absorption and its use or storage under the influence of insulin

70 Glycemic index illustrated One peaks about 2.3 (40) above baseline at 30 min AUC for white breads are 114, 95, 74 for high, medium and low GI, and 150 for glucose Another peaks about 2.2 (36) at 30 min GI = 100*AUCfood/AUCglucose A third peaks about 1.9 (29) at 30 min GI for bread are 76, 63, and 49 Returns gradually toward baseline at 120 min Reflects how well insulin secretion is matched to glucose absorption to maintain glucose level close to normal After 50 g of different white breads: AUC is measured for each bread for comparison with glucose and divided by AUC for glucose

71 Glycemic index general findings Highest glycemic index foods (>70) are white bread, white rice, potato, refined breakfast cereals, bagels, pretzels, glucose, maltose Lowest glycemic index foods (<55) are vegetables, most fruits, most intact whole grains, seeds, beans, nuts Intermediate GI foods are processed whole grain, pasta, sucrose, banana, converted rice However, many other factors enter in, so each food by each manufacturer and different cooking methods must be tested individually For example, whole wheat bread can have a high GI or a low GI, depending on exact manner in which it is prepared; rice has great variation depending on type, processing and cooking

72 Glycemic index - detailed

73 Glycemic load Which is better - a small amount of a high GI food or large amount of a low GI food? They give essentially the same AUC So, another measure is needed that incorporates both GI and amount of food That measure is the glycemic load, the product of GI of the food times the amount of CHO in the food on a given day, divided by 100 Example: A serving of potato containing 100 g of CHO that has a GI of 80 has a glycemic load of 100 x 80 / 100 = 80

74 Does the GI tool work? Do glycemic index and glycemic load give us a real handle on what carbs are good for us and which we should avoid? GI/GL has good rationale, since it relates to hyperglycemia in people with diabetes and metabolic syndrome, and the consequences However, is it really predictive of outcomes, especially in apparently healthy individuals?

75 Glycemic load and CHD Liu et al Am J Clin Nutrition 2000

76 Glycemic load and CHD - NHS Nurses Health Study 75,521 women ages No pre-existing CHD, stroke, CVD, or diabetes Detailed, repeated dietary histories Detailed accounting for confounding variables Follow-up of 10 years, during which 761 cases were observed

77 Glycemic load and CHD - NHS Explanatory variables examined Total amount of carbohydrate Amount each of starch, sucrose, fructose and lactose Glycemic load Glycemic index (glycemic load / total carb) Interaction with fat intake, BMI

81 Glycemic Load Effect on CHD by Body Mass Index

82 CHO & CHD Risk - Conclusions Total CHO, amount of starch, and amount of sugar per day are not associated with CHD risk But CHO, characterized by glycemic index and glycemic load, are highly associated with CHD Glycemic index 31% incr. CHD, Q5 vs. Q1 Glycemic load 98% incr. CHD, Q5 vs. Q1

83 CHO & CHD Risk - Conclusions High glycemic load diet does not increase risk in subjects with lower BMI, moderately increases risk in middle BMI and greatly increases risk in higher BMI individuals Consistent with observations that insulin resistance and CHO-induced hyperlipidemia are greatest in higher BMI individuals

84 CHO & CHD Risk - Restated Undisciplined CHO intake ranks among the most destructive possible personal habits, especially in susceptible individuals New information recognizes low salivary amylase as potential risk factor for obesity and metabolic syndrome / diabetes CHO can safely and effectively provide the majority of energy required to support an active life, provided: You favor low glycemic index CHO foods You limit amounts of high glycemic index CHO foods You keep your body mass index in a reasonable range You don't have an inherited metabolic tendency to produce abnormal quantities of undesirable lipids

85 Whole grain & CVD: Mechanisms Glucose absorption and metabolism Lower GI/GL; reduced insulin response, exposure to elevated glucose level Reduces insulin resistance, diabetes, metabolic syndrome

86 Whole grain & CVD: Mechanisms Fiber Binding of bile salts in intestine, causing greater loss in stool and interrupting enterohepatic bile circulation Reduces amount of cholesterol available for LDL synthesis More favorable lipid pattern Feeds the microbiome, which provides many services

87 Whole grain & CVD: Mechanisms Improved endothelial cell function Phytosterols Antioxidents Lower blood pressure Lower homocysteine

88 Whole grains & health: Conclusions Increasing whole grain consumption has been correlated with lower rate of all cause mortality, CVD, primarily CHD, in men and women, cancer, respiratory, infectious and other death Effectiveness seems concentrated in whole grain breakfast cereals and bran; brown rice and wheat germ to lesser extent Short-term feeding studies demonstrating effect on CVD markers negative thus far Fiber is the major contributor to health benefits of WG Dose-response relation of lower mortality maintained out to 210 gm/d (7 servings) for most specific causes, as well as all cause mortality

89 Whole grains: Recommendations Make whole grain breakfast cereal a regular feature in your diet Fiber content is a major benefactor, so should be maximized Select whole grain products with an eye on their glycemic index Not as easy as it sounds, since GI/GL data on U.S. products not easy to come by However, in general, it seems certain foods, such as pasta, are relatively low GI, especially if cooked al dente

90 Whole grains: Recommendations No health outcome basis on which to limit dietary whole grain intake; on the contrary, the more the better, up to seven servings a day

91 Finding Whole Grain Foods

92 Whole Grains I Eat Post Great Grains Raisin, Dates and Pecans Cereal Uncle Ben's Whole Grain Brown Rice Ronzoni Healthy Harvest Spaghetti Arnold Country 100% Whole Wheat Bread Crunchmaster Five-Seed Multi-Grain Crackers

Carbs: The Staff of Life, or The Stuff of Death? Ed Cox, M.D.

Carbs: The Staff of Life, or The Stuff of Death? Ed Cox, M.D. Pyramid, or Paleo? Carbs defined Carbohydrates (abbrev. CHO) = saccharides Saccharide from Greek for sugar Compounds of carbon, oxygen and