Introduction
Nutrition is the cornerstone of human health, influencing everything from energy levels to the risk of chronic diseases. It's the process of consuming and absorbing food that provides the body with essential nourishment. This involves breaking down food into nutrients, which are chemical substances crucial for bodily functions. Beyond basic sustenance, proper nutrition plays a vital role in disease prevention, healing, and even mental well-being. Understanding the fundamentals of nutrition empowers individuals to make informed dietary choices that support optimal health.
The Building Blocks: Macronutrients and Micronutrients
The nutrients in the food you eat benefit your body in different ways. Eating well involves balancing six major classes of nutrients: macronutrients, micronutrients, and water. Macronutrients provide energy and sustain bodily functions, while micronutrients, comprising vitamins and minerals, support metabolism and other essential processes. Water is essential for carrying nutrients and oxygen to cells, among other functions.
Macronutrients: The Foundation of Energy
If your body was a building, macronutrients would be the foundation. Macronutrients are your main source of energy. Macronutrients include:
Carbohydrates: Sugars, starches, and fiber are the primary energy source, fueling bodily functions. The body turns carbohydrates into glucose, a type of sugar. Simple carbs are made of one or two sugar molecules. Your body digests and absorbs these quicker than complex carbohydrates. Simple carbohydrates may raise your blood glucose higher and faster than complex carbs. Limiting how much added sugar you eat to no more than 10% of your daily calories can help lower your health risks. So can choosing more complex carbohydrates, like whole grains, beans, legumes, and starchy vegetables. Complex carbs can help you get more fiber, too. “If you eat a meal that is high in fiber, you feel fuller longer,” says Dr. Katherene Anguah, a nutrition researcher at the University of Missouri. Most Americans aren’t getting the recommended 14 grams of fiber for every 1,000 calories. Foods rich in fiber are important for gut health. They can also lower the amount of fat and cholesterol (a waxy, fat-like substance) in your blood. Fat and cholesterol buildup can lead to heart disease and stroke.
Lipids: Found in fats, oils, meat, and dairy, lipids store energy and aid in fat digestion. Although too much fat can cause trouble, you still need some in your diet. Fats are broken down into fatty acids. Your body uses these to make energy, build certain cell structures, absorb certain vitamins, and protect your organs. Experts recommend limiting a certain type of fat called saturated fats to less than 10% of your daily calories. Saturated fats are solid at room temperature, such as the fats in red meats, lard, and full-fat milk and dairy products. “Healthy fats have a place in the diet, but within reasonable calorie limits,” says Dr. Alison Brown, a nutrition scientist at NIH. It’s important to watch how much of them you eat. Fats have more than twice as many calories per gram as protein or carbohydrates, so can add extra calories to your day. Eating too many calories can lead to weight gain.
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Proteins: Proteins build and repair muscle tissue and regulate hormones. Proteins are needed for cells to perform critical functions in your body. They’re broken down by your body into amino acids. Proteins can also be used for energy. “They give a stronger sensation of fullness than carbohydrates,” says Dr.
Micronutrients: Vitamins and Minerals for Optimal Function
Micronutrients, including essential vitamins and minerals, are needed in smaller quantities than macronutrients but are vital for health.
Vitamins: Substances made by animals and plants, vitamins are primarily obtained through food. Many people take a multivitamin to ensure adequate intake.
- Vitamin A: Supports the immune system, metabolism, and vision.
- B Vitamins (B1-B12): Help convert food into energy and support blood vessels, brain, immune system, and nervous system.
- Vitamin C: Supports tissue growth, wound healing, and immune system strength.
- Vitamin D: Works with calcium to maintain healthy bones and supports brain health and the immune system.
- Vitamin E: Protects cells and maintains the health of red blood cells, white blood cells, platelets, brain, eyes, and skin.
- Vitamin K: Helps blood clot and prevents excessive bleeding.
Minerals: Minerals are obtained from animals that consume them and plants that absorb them, supporting various aspects of health.
- Calcium: Builds strong bones and supports the heart, muscles, and nervous system.
- Chromium: Helps the body process carbohydrates and fats.
- Copper: Supports brain development, the immune system, and the nervous system.
- Fluoride: Helps keep bones strong and prevents tooth decay.
- Iodine: Promotes brain development and thyroid health.
- Iron: Helps the body make hemoglobin, a protein in red blood cells. That’s because females lose iron through blood loss during menstruation.
- Magnesium: Makes new proteins and helps convert food into energy.
- Manganese: Protects cells from damage and helps the body make energy.
- Phosphorus: Builds and maintains strong bones and teeth, produces energy, and repairs cells.
- Potassium: Helps prevent high blood pressure and supports muscle health.
- Selenium: Supports thyroid health and reproductive health.
- Sodium: Helps cells absorb nutrients and supports muscle and nerve functions.
- Zinc: Boosts the immune system and protects vision.
Food Groups: A Balanced Approach
The long list of macronutrients and micronutrients come together in the five food groups that make up the balanced meals you need to have good nutrition:
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- Dairy
- Fruit
- Grains
- Protein
- Vegetables
Nutrition Through the Lifespan
Nutritional needs evolve throughout life. Babies, children, adults, and older adults require different nutrient combinations. Breast milk or formula typically meets most babies’ nutritional needs for the first six months.
Nutrition for Infants and Children
Breast milk or formula provides essential nutrients for the first six months. Solid foods can be introduced at six months, with guidance from a pediatrician to ensure optimal nutrition. In general, meals that include the five food groups give toddlers and children the right combination of macronutrients and micronutrients.
Nutrition for Adults
Adults can also benefit from meals based on the five food groups, but with adjustments based on gender and age. For example, females typically need more iron than males due to menstruation. The nutrient picture changes as we age. Medication or medical conditions may affect your appetite. When you eat less, you miss out on essential nutrients. People age 65 and older may benefit by focusing on foods that boost vitamin D and calcium for strong bones.
Medical Conditions Affecting Nutrition
Certain medical conditions can affect nutrition, leading to undernutrition and potential complications:
- Cancer cachexia: Cancer speeds up metabolism, causing the body to use more energy than it gets from food.
- Depression: Can lead to a loss of interest in planning and eating nutritious meals.
- Dysphagia: Difficulty swallowing can make it hard to eat certain foods, increasing the risk of nutrient deficiencies.
- Malabsorption syndrome: Conditions that prevent the body from absorbing nutrients.
These conditions can lead to macronutrient and micronutrient undernutrition, types of malnutrition that can cause serious health issues. Macronutrient undernutrition impairs energy production, while micronutrient undernutrition results in vitamin and mineral deficiencies.
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Healthy Eating: A Practical Guide
Good nutrition is about healthy eating. This means regularly choosing healthy foods and beverages. A healthy eating plan should give your body the energy and nutrients that you need every day. Nutrients include proteins, carbohydrates, fats, vitamins, minerals, and water. Healthy eating does not mean that you have to follow a very strict diet or eat only a few specific types of food. It doesn't mean that you can never eat your favorite foods. You can eat a variety of foods, including less healthy favorites. But it's important not to eat too much of those foods or have them too often.
Dietary Guidelines and Recommendations
The Dietary Guidelines for Americans offer guidance on what a balanced diet looks like. The guidelines suggest getting 10% to 35% of your calories from protein; 25% to 35% from fat; and 45% to 65% from carbohydrates. To find the amounts of different nutrients in a food, look at the Nutrition Facts label.
A healthy diet comprises a combination of different foods. These include:
- Staples like cereals (wheat, barley, rye, maize or rice) or starchy tubers or roots (potato, yam, taro or cassava).
- Legumes (lentils and beans).
- Fruit and vegetables.
- Foods from animal sources (meat, fish, eggs and milk).
Practical Tips for a Healthy Diet
- Breastfeed babies and young children: Feeding babies exclusively with breast milk from birth to 6 months of life is important for a healthy diet. It is also important to introduce a variety of safe and nutritious complementary foods at 6 months of age, while continuing to breastfeed until your child is two years old and beyond.
- Eat plenty of vegetables and fruit: People with diets rich in vegetables and fruit have a significantly lower risk of obesity, heart disease, stroke, diabetes and certain types of cancer.
- Eat less fat: To avoid unhealthy weight gain, consumption of total fat should not exceed 30% of a person's overall energy intake. Using unsaturated vegetable oils (olive, soy, sunflower or corn oil) rather than animal fats or oils high in saturated fats (butter, ghee, lard, coconut and palm oil) will help consume healthier fats.
- Limit intake of sugars: For a healthy diet, sugars should represent less than 10% of your total energy intake.
Reading Food Labels: Making Informed Choices
People look at food labels for a variety of reasons. The following label-reading skills are intended to make it easier for you to use the Nutrition Facts labels to make quick, informed food decisions to help you choose a healthy diet.
Key Components of the Nutrition Facts Label
- Serving Size: Pay attention to the serving size, especially how many servings there are in the food package.
- Calories: Calories provide a measure of how much energy you get from a serving of this food.
- Nutrients: Look at section 3 in the sample label. It shows you some key nutrients that impact your health. You can use the label to support your personal dietary needs - look for foods that contain more of the nutrients you want to get more of and less of the nutrients you may want to limit.
- Nutrients to get less of: Saturated Fat, Sodium, and Added Sugars.
- Nutrients to get more of: Dietary Fiber, Vitamin D, Calcium, Iron, and Potassium.
- % Daily Value (%DV): The % Daily Value (%DV) is the percentage of the Daily Value for each nutrient in a serving of the food. The Daily Values are reference amounts (expressed in grams, milligrams, or micrograms) of nutrients to consume or not to exceed each day.
General Guide to %DV
- 5% DV or less of a nutrient per serving is considered low
- 20% DV or more of a nutrient per serving is considered high
The Role of Government and Organizations
Governments have a central role in creating a healthy food environment that enables people to adopt and maintain healthy dietary practices. Effective actions by policy-makers to create a healthy food environment include the following:
- Creating coherence in national policies and investment plans - including trade, food and agricultural policies - to promote a healthy diet and protect public health.
- Promoting appropriate infant and young child feeding practices.
The WHO Global Strategy on Diet, Physical Activity and Health was adopted in 2004 by the Health Assembly. In 2010, the Health Assembly endorsed a set of recommendations on the marketing of foods and non-alcoholic beverages to children.