Carbohydrates, fiber and resistant starch in white potatoes – links to health outcomes Joanne Slavin Professor
Department of Food Science and Nutrition
University of Minnesota
October 14, 2014
From the Science to Me
My food journey and disclosures
• Grew up and worked on a dairy farm in Wisconsin which I still own with my 2 sisters – 2014 crops include pumpkins, soybeans, and corn, no potatoes
• Started as a dietitian; got PhD in Nutrition at UW‐Madison
• 6 years as Extension Nutritionist at U of MN • Teach Life Cycle Nutrition and Human Nutrition
• 30+ years of research in dietary fiber, whole grains, phytochemicals, and everything else
• Member of 2010 Dietary Guidelines Advisory Committee (DGAC)
• Serve on Scientific Advisory Council for APRE – Alliance for Potato Research and Education
• 100% Irish
Nutrient Adequacy ‐ Meet nutrient needs without exceeding calorie needs
‐ Dietary Reference Intakes (DRIs) ‐ Acceptable Macronutrient Distribution Ranges (AMDR) ‐ Protein: 10 ‐ 35% of kcal
‐ Carbohydrates: 45 ‐ 65% of kcal
‐ Fat: 20 ‐ 35% of kcal
‐ Recommended Dietary Allowance (RDA)
‐ Adequate Intake (AI)
‐ Tolerable Upper Level Intake (UL) The Science
Policy
Me
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Food advice: Evolution of USDA’s
Food Guidance – Moderation and Variety
1950s-1960s
1940s
Food for
Young
Children
1970s
1992
1916
2005
Carbohydrates in the Diet
• Vegetables, fruits, grains, legumes, and milk are main food sources of carbohydrates
• Grains and certain vegetables (potatoes, corn) high in starch (glucose) – except sweet potatoes (sucrose)
• Fruits and green vegetables contain little starch –
fruits mostly sugar
– Apples and pears high in fructose (66%), most other fruits 50/50 glucose/fructose (sucrose); milk 50/50 glucose/galactose
Does a carbohydrate equal a carbohydrate ‐ No
Fiber agreement
• Marker of a healthy diet •
•
•
•
•
Chemical structure – mono, di, polysaccharide
Digestible vs. non‐digestible
Speed of digestion and absorption – Glycemic index
Fermentable vs. non‐fermentable
Physical structure – in solution, part of a food, associated substances (protein), part of a seed or grain, particle size
– whole grains, fruits, vegetables, legumes
• Concept – carbohydrates and lignin that escape digestion in the upper GI tract but may be fermented in the gut
• Nutrient
– according to 2002 Dietary Reference Intakes (DRIs)
• Regulated
– On the Nutrition Facts panel – 25 g Daily Value (DV), may increase to 28 g DV 2
Dietary fiber intake is low
• Typical fiber intake in US is 15 grams per day – recommended levels are 25 – 38 g/day
• Most fiber‐containing foods – 1 – 3 g of fiber
– Apple – 2 grams
– Lettuce – 1 gram
– WW bread – 2 grams
– Oatmeal – 3 grams
• White flour and white potatoes provide the most fiber in the US diet, not because they are concentrated fiber sources, but because they are widely consumed
• Slavin. Health implications of dietary fiber. J Am Diet Assoc 2008;108:1716.
Current Intake of Resistant Starch
What is resistant starch?
Resistant
Starch
Starch – digested
in the small intestine
Fiber – fermented
in the large intestine
First Official Definition (1992)
“starch or starch degradation products not absorbed in the small intestine of healthy people.”
Relative Risk of Death From CHD Current Intake
Resistant Starch
1.
2.
Average in U.S.: 4.8g/day1
Range in U.S.: 2.7 – 8.0 g/day1
Worldwide: 3 – 10g/day2
Murphy M, Douglass JS, Birkett A. Resistant starch intake in the United States. J Am Diet Assoc. 2008;108: 67-78.
Baghurst PA, Baghurst KI, Record SJ. Dietary fibre, non-starch polysaccharides and resistant starch: a review. Supplement to Food
Australia 1996;48(3):S3-S35.
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Gut microbiota influence metabolism & body composition
Glycemic index
• Rating of carbohydrate‐containing foods according to their effect on blood glucose levels. • It compares 50 g of available carbohydrate from the test food with 50 g of carbohydrate from a reference, typically glucose
Vrieze et al, Diabetologia (2010) 53:606-613.
Glycemic index valuesa
Potato GI Varies from Low to High with
Variety and Preparation
• No official database
Variety
GI
Preparation
Fructose
15
Carisma
Sucrose
65
Marfona
56
Boiled 15 minutes
Glucose
103
Boiled potatoes
78
Charlotte
66
Boiled 15 minutes
58
53
Boiled 8 minutes
French fries
63
75
Russet Burbank
72
Baked whole, cooled, reheated
Boiled sweet potatoes
63
48
Russet Burbank
98
Microwaved 18 min
apple
36
40
Banana
51
70
Pontica
79
Microwaved whole, 7 min
Pontica
93
Baked whole
a. Values obtained from
1. Atkinson. Diabetes Care, 2008; 31:2281.
2. Foster-Powell. Am J Clin Nutr 1995;62:8715.
Cooking gelatinizes potato starch and enhances digestion
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Hierarchy of Evidence
Stronger
Evidence
RCT
Weaker
Evidence
Double Blinded
Intervention study
Prospective, cohort study
Clinical trial
Cross‐sectional study
Case Report
Expert Opinion
What is the relationship between glycemic index or glycemic load and body weight, type 2 diabetes, cardiovascular disease, and cancer?
• Strong and consistent evidence shows that glycemic index and/or glycemic load are not associated with body weight and do not lead to greater weight loss or better weight maintenance
• Abundant, strong epidemiological evidence demonstrates that there is no association between glycemic index or load and cancer
Carbohydrates and Health Outcome Questions in 2010 Dietary Guidelines Advisory Committee (DGAC)
• What is the relationship between glycemic index or glycemic load and body weight, type 2 diabetes, cardiovascular disease, and cancer?
What is the relationship between glycemic index or glycemic load and body weight, type 2 diabetes, cardiovascular disease, and cancer?
• A moderate body of inconsistent evidence supports a relationship between high glycemic index and type 2 diabetes
• Strong, convincing evidence shows little association between glycemic load and type 2 diabetes
• Due to limited evidence, no conclusion can be drawn to assess the relationship between either glycemic index or load and cardiovascular disease
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GI/GL and T2 diabetes in 8 European Countries
• GI and GL were not associated with incident diabetes
• An expansion of the GI tables and systematic GI value assignment to foods may be needed to improve the validity of GI values derived in such studies
• Digestible carbohydrate intake is not associated with diabetes risk and suggests that diabetes risk with high‐GI and GL diets may be more modest than initial studies suggested
– Sluoijs I et al. J Nutr 2013;143:93‐99.
DGAC Carbohydrate Chapter Summary – or the good carbohydrate
• Healthy diets are high in carbohydrate. AMDR for carbohydrates are 45 – 65%. A maximum intake of 25% of added sugars is suggested.
• Americans should choose fiber‐rich foods such as whole grains, vegetables, fruits, and cooked dry beans and peas as staples in the diet. Dairy products are also a nutrient‐dense source of carbohydrates.
• Carbohydrates are the primary energy source for active people. Sedentary people, including most Americans, should decrease consumption of caloric carbohydrates to balance energy needs and attain and maintain ideal weight.
DF and GI for Nordic Nutrition Recommendations
• DF is associated with decreased risk of chronic diseases and metabolic conditions
• There is not enough evidence that choosing foods with low GI will decrease the risk of chronic diseases in the population overall
• Suggestive evidence that ranking food based on GI might be of use for overweight and obese individuals
• Issues regarding methodology, validity and practicality of the GI remain to be clarified
– Overby NC et al. Food and Nutrition Research 2013.57:20709
Dietary Guidelines for Americans 1980 - 2010
2000
2010
1990
1980
1985
1995
2005
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Comparison of Consumption to Recommendations
Ch 4: Foods and Nutrients to Increase
LTM2
Dietary Fiber and Potassium in Common Fruits and Vegetables
Potatoes & Health: Macronutrients
Protein: 1-1.5% by weight
High biological value: 90-100 (Egg:100)
High in lysine
Lipid: 1.2% by weight
Carbohydrate:
Amylopectin: high amylopectin/amylose (3:1)
contributes to high glycemic response
Fiber: 1-2% by weight
NLEA Servings
Dietary Fiber ‐ g Potassium ‐ mg Potato, boiled 3.0
348
Iceberg lettuce 0.7
80
Tomato 1.8
351
Carrot 2.5
201
Sweet corn 1.8
286
Banana 3.1
422
Apple with skin 4.4
195
Orange 3.4
256
Green grapes 1.1
241
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Slide 28
LTM2
Frances - I will fill in this this slide and sort by fiber per 100 grams if you agree with the format. I included top consumed fruits/veg
and only one example of potatoes to be consistent.
Liz Marr, 10/16/2011
The role of potatoes and potato components in cardiometabolic health: A review
• Potatoes contribute key nutrients to the diet, including vitamin C, potassium, and dietary fiber
• Potatoes and potato components have a favorable impact on several measure of cardiometabolic health
–
–
–
–
Blood pressure
Blood lipids
Inflammation
Body weight
• Controlled clinical trials are needed to define the impact of potatoes on cardiometabolic health
• McGill et al. Ann Med 2013;45:467‐473.
Changes in diet and lifestyle and long‐term weight gain in women and men
• Prospective study of 3 cohorts – 120,877 US women and men
• Within each 4 year period, participants gained an average of 3.35 lbs.
• 4 year weight change was most strongly associated with intake of potato chips (1.69 lb), potatoes (1.28 lb), SSBs (1.00 lb), unprocessed red meats (0.95 lb), processed meats (0.93 lb)
• Specific dietary and lifestyle factors are independently associated with longer‐term weight gain
• Mozaffarian et al. New Eng J Med 2011;364:2392‐2404.
White Potato Consumption and Nutrient Intake in
Children & Adolescents, Freedman MR and DR Keast, Nutr Res 31
Income and race/ethnicity influence dietary fiber (DF) intake and vegetable consumption
(2011) 270.
• NHANES 2009‐2010 mean intake of DF across sex, age, race‐
ethnicity, family income, and poverty threshold.
• DF intakes low; children 14 g/d, adults 17 g/d
• Lower family income and living at less than 131% of poverty were associated with lower DF intakes among adults
• Total vegetable consumption is lower than recommended and including white potatoes has declined • Government policies that single out and discourage consumption of white potatoes, especially among low‐income individuals who receive food assistance, may lead to unintended consequences of further decreasing intake of dietary fiber
Based on 2003-6 NHANES Data, n=7332
Whole potato, french fries, or
oven-baked fries
% Children/Adolescents
Energy, % total
9-12%
Fat, % total
8-15%
>10% of total intakes
Fiber, B6, Potassium
>5% of total intakes
Thiamin, niacin, vitamins C & K,
P, Mg, Cu
Potatoes, including French Fries, provide shortfall
nutrients within energy requirements for children and adolescents.
• Storey & Anderson. Nutr Res http://dx.doi.org/10.1016/j.nutres.2014.08.016
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Vegetable cost metric show that potatoes and beans provide most nutrients per penny
• Estimated cost impact of meeting the USDA requirements using 2008 national prices for 98 vegetables, fresh, frozen, and canned
• Calculated per 100 grams, per 100 calories, and per edible cup
• Beans and starchy vegetables, including white potatoes were cheaper/100 calories than were dark‐green and deep‐yellow vegetables. • For the more frequently consumed vegetables, potatoes and beans were the lowest cost sources of potassium and fiber.
• Drewnowski & Rehm. PLoS ONE 8(5): e63277.doi:10.1371/journal.pone.0063277
Choices made by low‐income women provided with an economic supplement for fresh fruit and vegetable purchase
• Investigated whether providing supplemental financial support specifically for purchase of fresh fruits and vegetables would result in high uptake of the supplement, and what the individuals would choose to purchase.
• 602 women enrolled at 3 WIC sites in LA were recruited
• 90% use of vouchers
• 10 most frequently mentioned items were oranges, apples bananas, peaches, grapes, tomatoes, carrots, lettuce, broccoli, and potatoes.
• Low income women used the supplement and purchased a wide variety of fresh fruits and vegetables.
• Herman et al. J Am Diet Assoc 2006:106:740‐744.
Conclusions
• Consumption of a wide variety of vegetables will ensure adequate intake of dietary fiber, vitamins, and minerals
• Food costs, food availability, convenience, food traditions, and taste are key issues in food choice
• Arbitrary decisions, such as not allowing white potatoes in government programs, have unintended consequences of reduced intakes of dietary fiber and potassium, 2 nutrients of concern
• Solving important nutrition problems will require strong science and partnerships based on trust among academics, the government, commodity groups, activists, and food companies
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