Chapter 2 Guidelines for Designing a Healthy Diet

Chapter Outline Diet planning principles (2.1) Evaluating nutritional health (2.2, 2.3) Levels of nutritional status Deficiencies Food Guides – skip pages 53-59 Using My Plate (2.4 & Myplate.gov) Nutritional recommendations – DRI (2.5) Science behind nutritional research (2.6) Food labels (2.7) Health Claims

Planning a Healthy Diet Adequate Diet is a diet that provides enough energy to maintain a healthy diet and provides nutrients needed for optimal health General philosophy for an adequate diet….Eat a variety of foods in moderation.

Diet-Planning Principles (5) Balance Variety Nutrient density Energy density – Kcal control Moderation

Diet-Planning Principles Balance Diet that provides enough, but not too much of each type of food Don’t want overeating of one food type to “crowd” out intake of other nutrients….

Diet-Planning Principles Variety - Diet that includes a wide selection of foods within each food group Eat a variety of fruits, not just oranges Why? Variety within the fruit and vegetable groups has the added bonus of increasing the variety of phytochemicals in your diet.

Phytochemicals Phytochemicals – substances in plants that may contribute to health Examples – see page 12 Functional Foods – foods that provide health benefits beyond those of the known nutrients

Diet-Planning Principles Nutrient Density Select foods that provide the most nutrients for the least number of calories (nutrient dense foods) Skim milk versus soda (page 40) Foods with few nutrients and many calories are sources of empty calories.

Diet-Planning Principles Energy Density - Kcal Control Foods with low-energy density have low kcal per gram, page 41 Can eat “a lot” without many calories Select foods with low energy density for an intake that meets nutritional needs without excess kcal intake

Energy Density Measure of the kcal per gram of food _______ has the highest energy density of the 3 energy-yielding nutrients. Foods with a high energy density provide more kcal per gram than low density foods.

Energy Density

Diet-Planning Principles Moderation Eat moderate (small) portion sizes Moderate your intake of foods high in: Added sugars Salt Saturated and trans fats Cholesterol Alcohol

Diet-Planning Principles (5) Balance Variety Nutrient density Energy density – Kcal control Moderation

Levels of Nutritional Status Desirable/Ideal nutrition Intake is sufficient to meet daily needs and to keep nutritional stores full while maintaining a healthy body weight

Levels of Nutritional Status Borderline nutrition – a subset of undernutrition in text Intake is not sufficient to meet daily needs Drawing upon your stores Body is not prepared to handle times of stress Illness, pregnancy… May slows growth and development of fetus and growing child

Levels of Nutritional Status Undernutrition Intake does not meet daily caloric and nutrient needs and nutrient reserves are empty for some/all nutrients There is a decline in body functions due to the lack of nutrients Can be life threatening Medical intervention required

Nutritional Deficiencies Covert vs. overt deficiency Covert or sub-clinical – deficiency may be detected by lab tests, but not outward signs of the deficiency Overt or clinical symptoms– outward signs of the deficiency

Nutritional Deficiencies Primary vs. secondary deficiency Primary – inadequate intake of the nutrient Secondary – body doesn’t absorb adequate amounts, excretes too much…. Body “mishandles” the nutrient Diet history helps distinguish between these

Under-nourished Populations at increased risk: anyone living in poverty especially infants, children, pregnant women, elderly elderly in general, including those living in nursing homes pregnant teens drug and alcohol addicts individuals with eating disorders anyone with prolonged illness, including hospital patients

Overnutrition Over-nutrition – 2 aspects excessive caloric intake that leads to obesity Increase risk of obesity related diseases heart disease, diabetes…. overuse of vitamin supplements that leads to toxicity

Malnourished Comment on a commonly used term…. The term malnourished is most commonly used in reference to chronic under-nutrition It can also be used in reference to anyone with chronic poor nutrition that results in failing health

Evaluating Nutritional Status Background - Personal History SES Social history - living situation, marital status Personal and family health history Medications, supplements taken Educational level….. Anthropometric data (A) Height and weight Waist circumference % body fat

Evaluating Nutritional Status 3. Biochemical Assessment (B) Laboratory tests, eg Cholesterol level Iron, potassium, vitamin D levels Liver enzyme function 4. Clinical Assessment (C) Physical exam Hair, skin, eyes, tongue… Blood pressure

Evaluating Nutritional Status 5. Diet History (D) Typical foods eaten Food journal 6. Environmental Assessment (E) – part of background/personal history

The abc’s of evaluating nutritional status Anthropometric data Biochemical tests Clinical assessment Dietary intake Environmental status Living conditions….from background information see page 43

Diet Planning Guides Food Group Plans Food Group Plans include: Foods within each food group provide similar nutrients and are from similar food sources Plan recommends the amount of food to be eaten in each food group. Food Group Plans include: USDA Food Guide (Pyramid/MyPlate) DASH diet

Old Food Pyramid See board for updates!

2005 USDA Food Guide -MyPyramid

Food Pyramid  My Plate (6/11)

USDA Food Guide Assigns foods to 5 (6?) major food groups Recommends daily intake levels from each group Recommendations vary depending on caloric needs Recommends weekly intake goals for several food groups.

My Plate - Grains 5-8 ounces bread, pasta, cereal, rice Half should be from whole grains 1 slice of bread ½ English muffin, bun ½ cup cooked rice, pasta, cereal 1 ounce dry cereal

Fruits and Vegetables Make half your plate fruits and vegetable!

My Plate - Vegetables 2-3 cups vegetables Choose a variety from all 5 subgroups weekly (see next slide) 1 cup cooked or raw vegetables 2 cups leafy vegetables (raw) ¾ cup vegetable juice

Eat a Variety of Vegetables Vegetable subgroups Dark green – broccoli and dark greens Red, orange, yellow – carrots, peppers, winter squash, sweet potatoes Legumes – black beans, kidney beans, soybeans, navy beans…. Starchy – corn, peas, potatoes, lima beans Other – green beans, brussel sprouts, mushrooms, tomatoes, vegetable juices…

My Plate - Fruits 1 – 1 ½ cups of fruit Consume a variety of fruits No more than 1/3 from juices 1 orange, apple, banana (all medium size) ½ grapefruit ½ cup canned fruit or berries 3/4 cup fruit juice

My Plate - Dairy 3 cups/serving dairy Choose low/no-fat options 1 cup milk 80 kcal, skim 100 kcal, 1% milk 159 kcal, whole milk 1 cup yogurt 1 ½ ounces cheese (170 kcal for cheddar) Calcium enriched soy milk

Food Plate - Proteins 5-6 ½ ounces meat and meat alternatives Meat, poultry, fish, eggs, seeds, nuts, legumes – ounce equivalents ½ ounce nuts 1 egg 1/4 cup cooked legumes = 1 ounce 1 tablespoon pb

My Plate - Oils Oils – 5-7 teaspoons per day Olive oil Canola oil Corn oil Vegetable oil

My Plate – Empty Calories Fats and sugars – eat sparingly Butter, margarine Cream, sour cream, cream cheese, mayo. Candy, soda, sugar, honey…. Sports drinks, energy drinks

My Plate Strengths: Drawbacks:

Putting the Plan into Action Copyright 2005 Wadsworth Group, a division of Thomson Learning

MyPlate Physical Activity Adults should do at least 2 hours and 30 minutes each week of aerobic physical activity at a moderate level OR 1 hour and 15 minutes each week of aerobic physical activity at a vigorous level.

Science Of Nutrition Nutritional recommendations are based on scientific research. Recommendations attempt to define adequate intake.

Dietary Recommendations Dietary Reference Intakes (DRI) EAR - Estimated Average Requirements RDA – Recommended Dietary Allowances AI – Adequate Intake UL – Tolerable Upper Intake Levels All based on nutritional research.

EAR and RDA Estimated Average Requirements Intake amount that appears to meet the needs of 50% of the population Age, gender, “condition” based Set after review of many research studies Recommended Dietary Allowances RDA is set to meet the needs of 98% of the population (without reaching toxic levels)

DRI

AI Adequate Intake (AI) AI = average amount of the nutrient that a group of healthy people consume AI is set when there isn’t enough research to set an estimated average requirement (EAR) or RDA Examples: Vitamin D, water, fiber

UL Tolerable Upper Intake Level (UL) Maximum daily amount of nutrient that appears safe for most healthy people Intake above the UL is associated with toxicity symptoms Most often see with overuse of supplements or intake of many fortified foods

DRI

Other Recommendations Estimated Energy Requirements (EER) Caloric intake that will maintain energy balance in a healthy person Values given are for “reference” male and female who is fairly active Values are not very useful for individuals!

Energy – Why not set an RDA?

Other Recommendations Acceptable Macronutrient Distribution Range or, recommended intake of energy yielding nutrients 45-65% of caloric intake from carbohydrate 20-35% of caloric intake from fat 10-35% of caloric intake from protein

The Science of Nutrition One of the newest sciences New branch is nutritional genomics Study of the interaction of nutrients with DNA/genes and how those genes impact health Like all sciences, nutrition is based on scientific research

Scientific Method Observations  Questions Hypotheses  Predictions Test hypotheses/predictions Analyze data and draw conclusions Share results Page 64

Observations and Questions Make observations about diet and health. These observations lead to questions For example: The incidence of breast cancer is much lower in Japan than in the U.S. Diet in Japan is rich in…..while in U.S. diet is rich in …… Question?:

Develop Hypotheses and Make Predictions Hypothesis – tentative explanation of the observations or answer to the question Make prediction – If the hypothesis is true what else is true?

Experiments Conduct experiments to test the predictions Easier said than done when people are involved! We’ll consider research designs later/soon.

One Experimental Design When possible, randomly assign subjects to either a control of experimental group Goal is for two groups to be as similar to each other as possible Control Group – either no change to diet or given a placebo Experimental group – diet changed or given a supplement

Experimental Design Compare the health/lab values of the two groups before and after the diet change. Example – DASH diet study

Analyze results… Analyze results Draw conclusions about the validity of the hypothesis Test alternate hypotheses Share findings Publish in nutritional journals Present findings at conferences

Common Research Designs Epidemiological study (observe) Cross-sectional Longitudinal Case-control study Experimental (intervene) Animal studies Human clinical trials Double blind study Lab studies

The Science of Nutrition 1. Epidemiological studies Study of populations Look for correlations between dietary practices and health

Epidemiological Studies Cross-sectional - look for correlations between diet and health at a point in time Longitudinal Studies - Follow a group of people (a cohort) over a period of time Look for differences in diet that might account for the differences in health

Epidemiological Studies Case-control study – compare the diet of individuals with a condition to that of healthy individuals Again, do not change their diet…..just observe it. Go to page 65 if not already there…

Human Experimental Studies Often called a Clinical Study Randomly assign like people to either the experimental or control group Alter the diet of experimental group as compared to a control group Compare incidence of disease/lab values/ performance …. of two groups

Types of Clinical Trials Blind experiments Subjects do not know which group they are in Double blind experiments Neither subjects nor the researchers know which group the subjects are in until after the experiment is over Goal is to avoid bias in the reporting/recording of the data.

Experimental Studies Animal Studies Controlled studies in lab setting using animals Alter diet of experimental group Compare health/lab values of control and experimental groups Benefits? …. Drawbacks? ……

Experimental Studies Lab-Based Studies Also called in vitro studies Examine impact of a substance on living tissue in a “test tube” -------------------------------------------------------------

The Science of Nutrition Size matters Good studies have relatively large sample sizes Preliminary studies have smaller sample sizes Peer review matters Information in peer- reviewed research journals is much more credible than that in popular magazines, TV, Internet

Food Labels Ingredient list Serving size Listed by weight in product (most to least) Serving size Set by gov’t for each food type Not the same as the MyPlate serving

Food Labels Nutritional content compared to Daily Values Daily Values are estimates of the needs of 2000 kcal per day consumer Not the same as RDA – why?

Food Labels Specific nutrition facts Kcal/serving Kcal from fat Total fat, grams and % Daily Value (DV) Grams saturated fat, % DV Grams trans fats – added 2006 Cholesterol (mg and % DV) Sodium (mg and % DV)

Food Labels Nutrition Facts, cont’d Total grams carbohydrate Grams sugar Grams and % DV: fiber Grams protein % DV: Vitamin A Vitamin C Iron Calcium

Food Labels “Health” claims allowed on food labels are regulated by the FDA Law changed in 2003 to allow more health claims Much more confusing now Now health claims with limited evidence can now be put on labels with a “disclaimer”/explanation. Pages 68/69

Food Labels

Food Labels “Structure-function” claims do not require FDA approval Cannot mention a disease or symptom Limited regulation of claims on dietary supplements (since 1994)

Food Labels “May reduce the risk of heart disease.” A “health” claim Regulated and needs FDA approval. “Promotes a healthy heart.” A “structure-function” claim No FDA approval or proof needed to make

Other Recommendations Other countries and international organizations set their own nutritional recommendations e.g. World Health Organization (WHO)