Nutrition Quiz 1 Study Guide PDF

Preview

Summary

Nutrition Quiz 1 Study Guide Lecture 1: Nutrients: chemical substances in food that provide energy, structural materials, regulating agents to support growth, maintenance and repair of the tissues o Essential nutrient: a nutrient that MUST be obtained from food because the body cannot make or cannot...

Description

Nutrition Quiz 1 Study Guide Lecture 1:  Nutrients: chemical substances in food that provide energy, structural materials, and/or regulating agents to support growth, maintenance and repair of the body’s tissues o Essential nutrient: a nutrient that MUST be obtained from food because the body cannot make or cannot make adequate amounts to meet physiological needs  Other substances in food: o Health benefits (fiber) o Add flavor, texture and color (additives) o Have physiological effects (caffeine)  Alcohol is not a nutrient because it is destructive to body tissue  Caffeine is not a nutrient because it causes irregular heartbeats and raises blood pressure  6 classes of nutrients: o Carbohydrates o Lipids o Proteins  Composed of amino acids (9 essential amino acids) o Water  Most essential nutrient o Minerals o Vitamins  Macronutrients: energy yielding nutrients o Water (most essential), carbohydrates, fat, protein  Micronutrients: less present in the body (need smaller amounts) o Vitamins and minerals  Kilocalorie (Calories- upper case C): amount of energy it takes to raise the temperature of 1 kg of water by 1°C (measure of potential energy in foods) o Use a bomb calorimeter to figure out how many calories in a sample of food  Food is heated, energy is released in heat, heat energy is measured in kilocalories  1000 calories = 1 kcal o Carbohydrates: 4 kcal/g o Protein: 4 kcal/g o Fat 9kcal/g o Alcohol (not nutrient): 7 kcal/g  When finding total kilocalories  round down to the nearest 5

Lecture 2:  Causality is not made from one research study  Experimental Studies o Animal studies: compare two groups of animals to study the effect of nutrients/diet in health  Hypothesis generating o Cell culture studies  Hypothesis generating o Clinical trials/Intervention studies: a researcher is controlling what the individuals are doing  Hypothesis testing  Epidemiology: the study of disease o Epidemiologic research: distribution and determinants of disease frequency  Descriptive: concerned with distribution of disease in populations (who, what, when, where)  Hypothesis generating  Analytic: concerned with the determinants of disease  Hypothesis testing  Case Report: detailed report published by physicians on a single patient (on some unique aspect of that patient)  Case Series: characteristics of a group of patients with the same type of disease o Ex: AIDS  5 homosexual men has PCP, and it was found to do with their sexual behavior  Correlational (Ecological) Studies: uses data from populations to compare disease frequency o Between different groups during the same time period o In the same population at different points in time  How disease varies over time  Population data can have less error than individual research  Doesn’t allow for controlling the confounder  Hypothesis generating  Confounder: an outside factor that goes up or down with the experimental factor and can have an effect on disease (it is an independent factor on disease)  Cross-Sectional Studies: examine exposure and disease in individuals within a population at the same point in time o Hypothesis generating  Since the factors change in time  If the factors can’t change in time, then it can be used to test a hypothesis (ex: blood type) o Assesses disease and behavior at the same point in time to find an association  NHANES (biggest cross-sectional study) o National Health and Nutrition Examination Survey o Assesses health and nutritional status of adults and children in the US







 Every year they take a sample of 5,000 US representatives and collect data (ages 2+)  Data: demographics, nutrition, social economics, health and medical examinations  Hypothesis generating  Can be used to test hypothesis with non-changing factors o Relevant information about the prevalence of disease and other factors (like exposure)  Public health people use this information to target the population about health issues Case Control Study o Compare groups with the disease (cases) to a similar group without the disease (control) with respect to the proportion exposed  Select individuals on the basis if they have a disease  Ask the groups to remember specific exposure (recall exposure during latency period)  CONCERN: Recall bias: the people who have the disease recall their exposure differently than those who do not have the disease  Low on the pyramid of research studies, but effective for rare diseases Cohort Study o Classify non-diseased individuals with respect to exposure, follow over a specified period of time and compare rates of disease development  People don’t have the disease when the study starts  Follow people for a period of time consistent with latency period of disease  Compare people based on their exposure to a specific thing  After exposure, see if disease develops  Key approach for rare exposures o CONCERN: Loss to follow up: those may choose to drop out of the study based on their exposure, and since people drop out of the study it can affect the conclusion of the results o Ex: Nurses’ Health Study  Relationship of oral contraception and breast cancer  Choose nurses because…  Less likely to drop out  More medical knowledge  Easy to track (registered in nurses’ association)  Married woman who have mortgage and kids so they are grounded (not moving around) Clinical Trials/Intervention Studies o Exposure is assigned by the investigator o Need lots of data o Ethics: balance between possibility and uncertainty of benefit









o Issue of cost and feasibility  Hypothesis testing The Gold Standard (RCT  randomized controlled (clinical) trial) o Randomized: the assignment to the exposure is random (assigned by a computer)  Equal distribution of ALL confounders (including unknown) in each group, so the only difference should be exposure  The randomization computer system allows us to equally separate unknown confounders  Control group (placebo group): do not get exposure  Placebo-controlled: typically use a sugar pill instead of the treatment pill  CONCERN: If people know they are in this group they could exaggerate their pain, drop out of the study they could try to use the treatment on their own (placebo effect)  Experimental group: get exposure o Double blind: the researchers and the subjects do not know which group each person is in  You can typically only single blind in diet studies because people know what they are eating o Subjective outcome: the person has to rate something in order for the researcher to know (not as clear, hard to test) o Hard outcome: it is clear that it happened (easy to see cause and effect) Placebo Effect: a positive (or negative) response by subjects to a treatment regardless of the physiologic efficacy of what they receive o Often attributed to subject’s expectations o Minimize this effect by making the experience as similar as possible between the two groups Nutritional Epidemiology o Main Strength: direct relevance to human health (public health recommendations) o Major Limitations:  Complex nature of diets  Food consists of complex mixtures of compounds o Harder to know which ingredient is responsible  Dietary components are intercorrelated  Diet is imprecisely measured  Diet is weakly associated with disease, therefore difficult to detect (easier to have error) Meta-Analysis o Pools together results of individual studies to obtain an overall estimate of effect  Before: meta-analysis used RCTs to make one big sample group





 Now: meta-analysis throws similar RCT results together and tries to make a conclusion from all of them o The usefulness depends on quality of included studies o Potentially subject to publication bias o Best for use with clinical trials  Overall, still somewhat controversial Criteria for Causality o Consistency of findings o Strength of the association  Less bias or effects of outside factors o Biological plausibility o Time-sequence  There could be a threshold o Dose response Generalizability o Are the results applicable to populations other than the study population

Lecture 3:  Tools to encourage Healthy Eating o Dietary Reference Intakes (DRIs): nutrient recommendations  Reflect nutrient intake levels for dietary adequacy and optimal nutrition  They differ based on gender and age  Allows populations to develop nutrient programs, and set policy and guidelines o Dietary Guidelines for Americans: general dietary and lifestyle advice  Every 5 years, healthy eating patterns o MyPlate: food group recommendations  Showed a plate with visuals but not specific statistics  Harvard came out with the Healthy Eating Place (more specific, replaced dairy with water, showed exercise)  Older Adults: showed canned, frozen and dried fruits, and less sodium o Nutrient values on labels  Core Nutrient Concepts: o Adequacy: Food chosen provides all the essential nutrients, fiber, and energy in amounts sufficient to support growth and maintain health o Balance: need proportions of food groups, energy sources and energy o Calorie Control: form of energy (energy intake= energy expenditure) o Nutrient Density: provide substantial amounts of vitamins and minerals with relatively little kcals  Little or no solid fats and added sugars, refined starches and sodium  Ratio of nutrient content to energy content (changes depending on preparation)  Calorie budget











 

 Elderly need more calories and nutrient dense foods  Children need less calories and nutrient rich food  Nutrient dense foods vs. empty calorie foods  People are overweight because they choose empty calorie foods o Moderation: quantity and frequency  Not too much or not too little o Variety: across the food groups and within food groups  More likely to meet overall nutrient needs Estimated Average Requirement (EAR) o Amount that meets the nutritional requirement of 50% of people in a life stage/gender group Recommended Dietary Allowance (RDA) o Amount that meets the needs of most people (about 98%) in a life stage/gender group o It is 2 standard deviations about the EAR o An overall goal people want to achieve in consuming a nutrient Adequate Intake (AI) o Amount thought to be adequate for most people to maintain good health (an estimate, use NHANES data) o AI is used when there isn’t enough research for an EAR (science based)  A nutrient cannot have both and AI and an EAR Tolerable Upper Intake Level (UL) o Highest level of daily nutrient intake that is likely to pose no risk of health effects for nearly all persons in the general population o It is not a goal, it is a ceiling o Determined: they bring down the statistics 20% to cover everyone o Very unlikely to reach a UI, unless you are taking supplements AMDR: Acceptable Macronutrient Distribution Ranges o Carbohydrates (45-65%) o Fat (20-35%) o Protein (10-35%)  There is no evidence for an optimal proportion of macronutrients for weight loss Estimated Energy Requirements (EER) o 4 Factors: age, weight (kg), height (m), Physical Activity (PA factor) Healthy eating pattern: o Whole Fruits o Vegetables (dark green, red and orange, legumes, starchy, other) o Protein (seafood- 8oz a week, leaner cuts, eggs, nuts, seeds, legumes) o Dairy (low fat/nonfat) o Grains (at least ½ whole grains)  Limit intake of refined grains (milling process) o Oils (avocado, nuts, seeds)







o LIMIT:  Saturated and trans fat (...