HLT 201 Chapter 1, Spring 2016

HLT201 Chapter 1: Nutrition and healthy diet Omar Bou Hamdan, MD Introduction to nutrition  It is necessary to have an understanding of the nutritional needs of the body, i.e. the dietary constituents and their functions within the body.  A good balanced diet and dietary habits are essential for good health. Healthy Diet  A healthy diet is one that helps maintain or improve health.  It is important for the prevention of many chronic health risks such as: obesity, heart disease, diabetes, and cancer A healthy diet involves consuming appropriate amounts of all nutrients A nutrient is any substance that is digested, absorbed and utilized to promote body function. These substances are:  Carbohydrates (sugars)  Proteins  Fats  Vitamins  Mineral salts  Water Nutrients These nutrient classes can be categorized as either: 1. Macronutrients :needed in relatively large amounts 2. Micronutrients :needed in smaller quantities Nutrients Macronutrients  Carbohydrates  Proteins  Fats  Fibers  Water Micronutrients  Minerals  Vitamins Carbohydrates Found in rice, noodles, bread, and other grain-based products Carbohydrates: 50-55% Of total daily calories They are the principle source of energy to the body Carbohydrates Simple Sugars  Quick absorption  Raise the blood glucose level rapidly  e.g: Sucrose (Table sugar) Related to Heart diseases Complex Sugars  Longer time to digest and absorb  E.g: Starch Carbohyrates Dietary guidelines generally recommend that complex carbohydrates (starches) and nutrient- rich simple carbohydrates such as fruits and vegetables, and dairy products make up the bulk of carbohydrate consumption Glycemic index  The glycemic index of a carbohydrate represents how quickly its consumption increases blood sugar levels.  Values range from 1 (the slowest) to 100 (the fastest, the index of pure glucose).  The glycemic index tends to be lower for complex carbohydrates than for simple carbohydrates, but there are exceptions. For example, fructose (the sugar in fruits) has little effect on blood sugar. Glycemic index  The glycemic index is thought to be important because carbohydrates that increase blood sugar levels quickly (those with a high glycemic index) also quickly increase insulin levels.  The increase in insulin may result in low blood sugar levels (hypoglycemia) and hunger, which tends to lead to consuming excess calories and gaining weight.  Carbohydrates with a low glycemic index do not increase insulin levels so much. As a result, people feel satiated longer after eating.. Glycemic index Consuming carbohydrates with a low glycemic index also tends to:  result in more healthful cholesterol levels and  reduces the risk of obesity  Reduces the risk of diabetes mellitus and, in people with diabetes, the risk of complications due to diabetes Proteins Proteins  The most abundant substances in the body  Basis of body structures: muscles, bones and hair  Few amount is used for energy production  Requirement is 60 g/day, 10- 15% of total calories Sources: Animal: Meat/ Egg/ Dairy products/ Fish/ Chiken Plant: Soy/ Grains/ Legumes Proteins Animal Proteins  Complete as they contain all the essential amino acids which the body can’t make  Also contains saturated fats which increase the CHD risk Plant Proteins  Partially complete as they lack few essential acids  Can be combined together to form a full protein  Less risk of heart diseases Functions of proteins  Growth and repair of body cells and tissues  Synthesis of enzymes, plasma proteins, antibodies (immunoglobulins) and some hormones  Provision of energy.  When protein is eaten in excess of the body s needs, it is converted to fat. Fats/ Lipids Fats The type of the fat consumed is more important than the amount of total fat They are packed with calories : Provide 9 Cal/g compared to 4 Cal /g in proteins and carbs Fats  Recommendations Fat should contribute to <30% of total calories  The body stores excess fat in: - Abdomen (omental fat) - Skin (subcutaneous tissue) - Blood vessels leading to atherosclerosis - In organs as liver leading to dysfunction Functions of fats  Provision of a source of chemical energy and heat  Storage of energy as fat in adipose tissue under the skin when eaten in excess of requirements  Insulation as a subcutaneous layer it reduces heat loss through the skin  Satiety when gastric contents containing fat enter the duodenum, the emptying time of the stomach is prolonged, postponing the return of hunger. Fats Associated with increased cholesterol levels in the body and coronary heart diseases Fats Saturated •Monounsaturated •Polyunsaturated •Transfats Unsaturated Fats Saturated  Solid at room temperature  Animal source: cheese, butter, red meat, whole milk Unsaturated fats  Liquid at room temperature  E.g: Oils Transfats These are rare in nature and in foods from natural sources; They are typically created in an industrial process called partial hydrogenation. Omega 3 fatty acids  A diet rich in omega-3 fatty acids may reduce the risk of coronary artery disease.  Lake trout and certain deep-sea fish contain large amounts of omega-3 fatty acids. Lipids and cholesterol level Different types of dietary fat have different effects on blood levels of cholesterol:  Monounsaturated fats tend to lower LDL and raise HDL  Polyunsaturated fats tend to decrease both types of cholesterol;  Saturated fats tend to either raise HDL, or raise both HDL and LDL;  Trans fat tend to raise LDL and lower HDL. Lipids Type of Fat Source Monounsaturated Avocado, olive, and peanut oils Peanut butter Polyunsaturated Canola, corn, soybean, sunflower, and many other liquid vegetable oils Saturated Meats, particularly beef Full-fat dairy products such as whole milk, butter, and cheese Coconut and palm oils Artificially hydrogenated vegetable oils Type of fat Source Omega-3 fatty acids Flaxseed Lake trout and certain deep-sea fish, such as mackerel, salmon, herring, and tuna Green leafy vegetables Walnuts Omega-6 fatty acids Vegetable oils (including sunflower, safflower, corn, cottonseed, and soybean oils) Fish oils Egg yolks Trans fats Commercially baked foods, such as cookies, crackers, and doughnuts Some french fries and other fried foods Margarine Shortening Potato chips Fibers Fibers  Dietary fiber consists of the indigestible part of plant foods: Mechanical benefit Ex: Pectin, cellulose, gum…  Decrease the risk of coronary heart disease and stroke,protects against type 2 diabetes, and colon cancer, prevents constipation  Sources: Whole grains/ Breakfast cereals/ Fruits and vegetables To meet your fiber requirements: 30g/day  Eat plenty of fresh fruits and vegetables  Eat a whole fruit rather THAN FRUIT JUICE  Do not overcook vegetables and eat some raw  Eat the skin of fruits and vegetables  Choose whole grain cereals, wholemeal bread Water WATER Water  It constitutes 70% of non fat mass of the body  Requirements: 8-10 glasses daily (2Liters)  20% of water intake comes in food  A large amount of water is lost each day in feces, sweat, breath, and urine. FUNCTIONS OF WATER  provision of the moist internal environment which is required by all living cells in the body,  participation in all the chemical reactions which occur inside and outside the body cells  regulation of body temperature Vitamins VITAMINS Water Soluble: B, C. Fat Soluble: A,D,E,K. NO caloric Value Vitamins  Vitamin A (retinol): Night vision Vitamin D Vitamin D regulates calcium and phosphate metabolism Deficiency result in Osteoporosis Adequate calcium and vitamin D intake are important, particularly in women, to reduce the risk of osteoporosis in which bones become weak, thin and easily fractured Vitamin D Folate Folate is a type of B vitamin that is important in the production of red blood cells. Low levels of folate in pregnant women have been linked to a group of birth defects called neural tube defects, which includes spina bifida and anencephaly. Folate MINERALS Iron Calcium Sodium NO Caloric Value Iron  Iron is an essential element for blood production.  Mostly found in the red blood cells as hemoglobin, which transfers oxygen in the blood  It is also a component of certain proteins essential for body functions  Some foods rich in iron include:  Meat and Poultry  Seafood  Vegetables (Greens, beans…)  Iron deficiency causes anemia Antioxidants Antioxidants are substances that may protect your cells against the effects of free radicals. Free radicals are molecules produced when your body breaks down food, or by environmental exposures like tobacco smoke and radiation. Free radicals can damage cells, and may play a role in heart disease, cancer and other diseases. Antioxidants are found in many foods. These include fruits and vegetables, nuts, grains, and some meats, poultry and fish. Antioxidants Antioxidant substances include  Beta-carotene  Lycopene  Selenium  Vitamin A  Vitamin C  Vitamin E Healthy eating guidelines PYRAMID/ PLATE Figure 1: The main food groups and their recommended proportions within a balanced diet Healthy Eating plate WHO recommendations The WHO makes the following 5 recommendations for a healthy diet:  Achieve an energy balance and a healthy weight  Limit energy intake from total fats and shift fat consumption away from saturated fats to unsaturated fats and towards the elimination of trans-fatty acids  Increase consumption of fruits and vegetables, whole grains and nuts  Limit the intake of simple sugar. A 2003 report recommends less than 10% simple sugars.  Limit salt/ sodium consumption from all sources and ensure that salt is iodized Healthy Diet  Limit intake of refined sugars  Limit the intake of fat especially saturated fat (use Low fats when possible)  Avoid transfats  Limit your sodium intake (substitute with herbs and spices)  Reduce your consumption of artificial colorings, preservatives and other food additives  Eat more fruits and vegetables (whole fruits)  Drink enough water  Get your calcium rich foods Summary  The first principle of a healthy diet is simply to eat a wide variety of foods.  You should also try to maintain a balance between calorie intake and calorie expenditure—that is, “don't eat more food than your body can utilize” THANK YOU