Nutrition is the science that interprets the interrelations of nutrients and other substances in food in association with maintenance, growth, health, and disease of an organism. It includes food intake, absorption, assimilation, biosynthesis, catabolism, and excretion. The diet of an organism is what it eats, which is largely determined by the availability and palatability of foods. For people, a healthy diet includes the preparation of food and storage methods that preserve nutrients from oxidation, heat, or leaching, and that reduce the risk of foodborne illnesses.
Nutrients are substances that must be obtained from the diet because the body cannot make them in sufficient quantities to meet physiological needs. Essential nutrition comes from food because the body cannot make them at all or cannot make them in sufficient quantities to meet physiological needs. Nutrition has been part of interprofessional science for historical periods. The young science of nutrition is a field that can evolve because only recently in human history have we become interested and able to answer two important questions: What, in food and with what, do they nourish? Nutrition carries implications for improving fertility, growth, development, and operational capabilities, disease prevention, and excellent functioning of the body and mind in the population and in individuals. An interest in nutrition has often been sparked by individual observation. Research continues with increasing intensity. It can be science in a more precise measurement to achieve the main goal: standardizing experimental procedures, improving treatment protocols, and eventually improving nutrition through technology.
Nutrition is a ubiquitous aspect of everyone’s life, not just the realm of scientists, dietitians, and healthcare professionals. Every day, everyone eats foods made from vegetables, fruits, herbs, dairy, or processed ingredients. From what they eat, the body will get energy to move and work, to thrive and strive. This knowledge of nutrition becomes a mandatory passport for each of us so that it is not wasteful to eat correctly and responsibly, and it does not lead to errors that result in a variety of food intolerance diseases.
Definition and Importance of Nutrition
Nutrition is derived from the Latin word for nourishment. Nutrition is the science of the intake of food, the assimilation of nutrients, and the body’s response on a biological and physiological level. This science crosses many disciplines. Each person has unique nutritional needs. What is nutritious for one person may not be so for another. Nutrients are chemicals that an organism needs to live and grow. Nutrients are used to build and repair tissues, regulate body processes, and are converted to and used as energy. It is important for all life. When one does not consume the minimum nutritional requirements over a period of time, a deficiency occurs. Deficiencies are a source of disease. Conversely, it is also possible to consume more than the required number of nutrients. Consumption of nutrients above one’s needs can enhance disease. This is nutrition beyond what is required. Whether it is a state of deficiency or nutrition beyond necessity, nutrition and health go hand in hand. Nutrients help to promote fitness, enhance longevity, and improve the quality of life. Nations incorporate nutrition into their public health policies in order to help improve the population’s well-being. The scientific study of nutrition continues to change and evolve. Finally, more research has shown individual differences in nutrient needs. Science has shown links between the intake of specific nutrients and diseases. Blood levels of nutrients give a clearer picture of what a person needs. Lifestyle issues can be overcome with a plan. Convince yourself how nutrition can enhance your well-being. Knowing what to eat is just as important as knowing what not to eat. These are some of the reasons you should make the study of nutrition a part of your life.
Macronutrients
Macronutrients are the large classes of nutrients that provide energy and are necessary for human life. Macronutrients include carbohydrates, proteins, and fats, which each provide a general grouping of nutrients with specific health benefits and functions in human biology. The body can derive energy from fat, carbohydrates, protein, and alcohol. Such nutrients also provide energy for the body’s metabolic processes. Energy-yielding macronutrients are essential for the growth and maintenance of bodily functions. Carbohydrates, proteins, and fats have caloric content and therefore make up the bulk of total energy intake. Carbohydrates are organic compounds structurally composed of sugar subunits. In human nutrition, carbohydrate refers to all substances that the body can convert into monosaccharide molecules and use for energy. Carbohydrates are the body’s main fuel and supply the most efficient dietary energy, as an estimated 40–60% of daily calories consumed come from carbohydrates. Proteins in the diet are broken down into their amino acid components. These amino acids are then used to make other proteins the body needs. There are about 10,000 different proteins in the body, and each protein is made up of a unique combination of amino acids. There are 20 amino acids used to make proteins, and they can be divided into the following two categories: essential amino acids and nonessential amino acids. Essential amino acids are those that the body cannot make and must be obtained from food. Fat is an energy-dense macronutrient that provides a concentrated source of energy. In addition to providing energy, fat is needed for several other useful functions in the human body. Every time you swallow a bite, your body begins a series of chemical reactions that break down the chemical compounds in food into smaller, simpler compounds. Fats, proteins, and carbohydrates will be broken down as different elements in the body. You will certainly not be a nutrition expert, but you are confident in your food options! Understanding the composition of macronutrients in food is important because they have specific effects on the body. It is important to consume enough of the right kinds of foods in the right balance in order to stay healthy.
Carbohydrates
Carbohydrates include sugar, starch, and fiber found in grains, fruits, vegetables, and milk products. They are classified into simple carbohydrates, such as fruits and sugar, and complex carbohydrates like bread, pasta, and rice. As the body’s primary energy source, carbohydrate intake should be between 45% and 65% of the diet of a healthy individual. The body breaks down carbohydrates into glucose, the primary fuel for cellular function. The best sources of carbohydrates are high in fiber. Fiber is a carbohydrate that cannot be digested and, although it is not an energy source for the body, it is essential for digestion. High-fiber carbohydrates are primarily found in a variety of vegetables, fruits, and whole grains. They help maintain healthy blood sugar levels, lower the risk of colon cancer, diabetes, heart disease, and reduce symptoms from irritable bowel syndrome and diverticulosis. While most vegetables and fruits are high in fiber, others are not. Potential carbohydrate sources include cookies, pasta, sodas, and nuts. Eating low-fiber carbohydrates and high-fiber carbohydrates results in different blood sugar outcomes based on glycemic index values. Consuming more high-fiber carbohydrates can keep blood sugar levels consistent, supporting healthy weight management and reducing the risk of diabetes. Carbohydrate deficiency symptoms can include malaise, weakness, and fatigue; however, there is not an actual carbohydrate deficiency disease. Eating too few carbohydrates is not common because they are widely available and many foods contain them. On the other hand, carb intake can be excessive and lead to excess energy intake and weight gain. More than two in three adults are considered to be overweight or obese in the United States alone. Furthermore, the body can convert carbohydrates to body fat if necessary for storage. The debate around the importance of carbohydrate quality compared to quantity is ongoing, particularly for individuals with medical conditions. As a result, understanding carbohydrates is important for promoting wellness and helping prevent dietary-related chronic disease.
Proteins
Proteins are the building blocks of the human body and are made up of one or more of 20 amino acids. These amino acids are broken down into two categories: essential amino acids and non-essential amino acids. Essential amino acids are the ones that the body is unable to make for itself, so you must get them through the food that you eat. Meat, fish, cheese, yogurt, and eggs are all good sources of complete protein, as they contain all of the nine essential amino acids. On the other hand, plant-based foods like beans, lentils, tofu, tempeh, soy milk, seeds, and nuts are good sources of protein, but they do not contain all the essential amino acids. The essential amino acids from plants can be combined in the same diet to get the benefits of them.
A small portion of protein is broken down into blood glucose, which is used to fuel the brain and nervous system when carbohydrates are running low. Proteins also play a role in muscle strength and require protein to repair and build muscle. Proteins also make up your enzymes, making proteins important in the digestion of your food and also helping with hormone regulation. If your diet is not sufficient in protein, your body can’t make enzymes fast enough, which can lead to deficiencies in your health. People who are getting older may need to have more protein because the body gets less efficient at absorbing protein. People over the age of 65 need more protein to put the brakes on muscle loss that comes from the aging process.
Fats
Fats play an essential role in providing energy when carbohydrates are not available. They become the major fuel source for muscles during tough endurance activities like running a marathon. Your body needs fats for proper growth and development and also requires them for a number of important functions. Dietary fat plays a major role in your cholesterol levels. The bad fats, saturated and trans fats, tend to have a very negative effect on your cholesterol levels. Saturated fats contribute to clogged arteries by increasing the level of LDL cholesterol. Trans fatty acids, also called trans fat, found in partially hydrogenated oil, also increase the level of LDL and lower the good HDL cholesterol.
There are four types of fats (saturated fat, trans fat, polyunsaturated fat, and monounsaturated fat). Choose foods that have the best types of fats. Monounsaturated and polyunsaturated fats are better for you than saturated fats and trans fats. Saturated fat and trans fat increase the risk of coronary artery disease. Some common sources of omega-6 fatty acids are vegetable oils, soy, corn, and mayonnaise. This is the major fat in most people’s diet. Because omega-6 fatty acids compete for the same enzyme to be converted into the anti-inflammatory, heart-healthy omega-3 fatty acids, it’s not recommended to get more than 10 percent of your energy from omega-6 fatty acids. A better goal is to limit omega-6 intake and focus on foods that are good sources of omega-3s.
Micronutrients
Micronutrients are different from macronutrients because, in addition to needing them in smaller quantities, they are necessary to maintain good health and prevent nutritional deficiencies. Micronutrients consist of two main groups: vitamins and minerals. Micronutrients work together with macronutrients to support normal bodily functions. Vitamins are vital for growth, immune functions, cell and tissue maintenance, and other vital processes. Minerals help with growth, fluid balance, oxygen transport, and other crucial functions of various organs, tissues, and cells. Consuming a variety of naturally occurring foods can increase the intake of vitamins and minerals.
Some of the best food sources of certain micronutrients include carrots—a good source of vitamin A; milk—a good source of calcium; and strawberries—a good source of vitamin C. Deficiencies of vitamins and minerals can lead to serious health complications. In addition, deficiencies in one or more micronutrients can lead to several health concerns, ranging from permanent conditions to rapid weight loss or, in some cases, death. They can also make chronic diseases worse. There are certain groups of people that may need more of certain types of micronutrients, such as vitamin D for older people and calcium for pregnant women. The bioavailability of the nutrient is the portion of the amount consumed that the body can more readily absorb and use. The amounts of vitamins and minerals necessary for health are very small and are measured in grams. Increasing the recommended amounts of vitamins and minerals would not significantly increase their effectiveness in preventing chronic disease. Consumption of adequate amounts of vitamin- and mineral-rich foods can supplement the need to consume supplements to reach nutrient goals for the prevention of chronic disease.
Vitamins
A vitamin is an organic compound necessary for various metabolic and physiologic processes essential for life. The body must have vitamins to grow and develop normally. There are 13 essential vitamins, which are divided into two groups: water-soluble and fat-soluble. Water-soluble vitamins are easily absorbed by the body, which has a limited ability to store them. They are found in plant and animal foods or dietary supplements and are not stored in your body. Because our bodies do not store water-soluble vitamins, we need to take them more frequently. When consuming excess amounts of water-soluble vitamins, our bodies begin to remove them before they can be used. There are nine water-soluble vitamins: – Vitamin C helps you form blood vessels, cartilage, muscle, and collagen, and aids in wound healing, strengthens bones and teeth, and aids in iron absorption. – B vitamins are essential for energy production, immune function, and iron absorption in the body; they are also important for the metabolism of carbohydrates, fats, and proteins that can be converted into energy in the body. Many people are getting too little water-soluble vitamins, which is leading to health problems. Water-soluble vitamins are easily destroyed or washed out during food storage or preparation. They are also lost when food is overcooked. The body may not be able to get all the vitamins it needs from especially restrictive diets. Water-soluble vitamins travel freely through the body, and excess amounts usually move out through the urine. That means it is very hard to get too much of a water-soluble vitamin in everyday food.
Minerals
Some of the main minerals in the body include calcium, needed for bone health, and potassium, which the body requires for the functioning of the heart muscle and is involved with fluid balance and nerve transmission. Many minerals also function as cofactors of enzymes. There are two classes of minerals: major minerals and trace minerals. Major minerals include those we require in amounts greater than 100 mg and include minerals such as calcium, potassium, phosphorus, and sodium. Trace minerals, or those we need in smaller amounts, include minerals such as iron and zinc. People should eat a diverse, balanced diet to get an adequate supply of minerals. Deficiencies in certain minerals can cause serious health problems, while other minerals have been linked to chronic diseases.
Plants obtain minerals from the soil they grow in. In certain soil types, the levels of minerals in the plants may be low; this puts consumers at risk for mineral deficiencies. For example, people living in iodine-deficient regions or those who get very little iodine out of choice may suffer from iodine deficiency, leading to toxic goiters in adults, mental retardation in infants born to iodine-deficient mothers, and cretinism. The bioavailability of minerals is affected by whether the given food has other compounds that enhance or hinder the absorption of minerals in the gut. For example, the bioavailability of the iron found in meat is much higher than that found in plant food. Indeed, vegetarians should make new food choices to ensure they consume enough bioavailable iron. The absorption of non-heme iron, which makes up 85% of the iron in the diet, is helped by vitamin C and other foods. The absorption of minerals such as calcium is more complex and relies on multiple factors, including the body’s need for calcium, the presence of vitamin D, and certain food components. Calcium from milk and milk products is much better absorbed by the body than calcium from plant foods. High levels of protein and sodium in the diet increase the body’s need for calcium, while high levels of calcium and dietary fat in the diet reduce the body’s need for and absorption of calcium. Adequate dietary calcium and vitamin D are crucial to optimal bone health. Dietary recommendations suggest adequate mineral intake. For example, AI for calcium recommends 1,000 mg/day for adults 19-50 years of age. The body also has the ability to excrete excess minerals. Mineral intake can affect chronic disease. For example, a diet high in sodium is associated with an increased risk for cardiovascular disease. However, there has historically been a lack of data from large, long-term trials to examine how different mineral intake amounts, such as calcium, from dietary sources affect an individual’s chronic disease risk. Further research is needed in this area.
Nutrient Absorption and Metabolism
Once in the digestive tract, many factors influence how individual nutrients are processed. For instance, dietary intake affects the stomach’s secretion of acid and enzyme activation. The two main pathways supporting the absorption of nutrients include active and passive transport. Active transport is an energy-requiring process in which nutrients are absorbed against a concentration gradient, via a transporter molecule that facilitates nutrient uptake. Dietary lipids are absorbed in the form of long-chain fatty acids and monoglycerides; this absorption process is unique because it requires emulsification with bile salts in the small intestine, which is not advantageous to absorption. This leads to the accumulation of fat-soluble nutrients during digestion. Passive transport, however, is an energy-requiring process in which nutrients are absorbed down a concentration gradient. In the case of hollow nutrients, transporters are often required to facilitate the absorption of nutrients, unlike disaccharides or monosaccharides, where no specific transporter is required. Nutrient bioavailability is affected by the way nutrients are processed by the food matrix, processing methods, food preparation, storage, age, gender, health status, pharmaceuticals, gut microbial population, dietary composition, and genetics. Following ingestion, nutrients generally undergo complex metabolism before being utilized for energy, cellular development, growth, tissue repair, or metabolism-regulating activities. Many nutrients are metabolized as precursors to a particular substance or intermediary metabolites via a series of metabolic reactions catalyzed by enzymes. Macronutrients can be catabolized to produce energy. Two pathways are heavily dependent on the duration and intensity of the exercise: anaerobic and aerobic. Some nutrients may support cell signaling directly or indirectly. Once ingested, nutrients become available to the body either as consumed in food products, as stored within organisms, or after undergoing digestion. The body’s cells specialize in nutrients; those in the gastrointestinal tract rely on them for protection. Absorption is the process of incorporating nutrient components into the body, regardless of the site where it occurs. Most dietary nutrients and the majority of water are absorbed by the small intestine; fluids are absorbed from the stomach, and water is absorbed from the colon and, to a certain extent, from the stomach. The volume of nutrients ingested, nutrient solubility, chemical form, diffusion rate and diffusion layer thickness, gastrointestinal motility, and length of transit time through the small intestine all influence nutrient absorption in the small intestine. Following absorption into the enterocytes in the gut, nutrients are further processed to facilitate their metabolism. As the body does not require absorbed nutrients in the form they are found in food products, the processing of nutrients is important. Nutrient metabolism involves the conversion of foods into a form that can be taken up by cells, oxidized as fuel, converted to fat, glycogen, protein, stored in special tissue depots, or excreted. Insufficient knowledge of either nutrient absorption or metabolism leads to the inability to develop strategies like functional foods. Further, studies in which either nutrient metabolism or absorption is impaired have revealed that proprietary products have low efficacy, thereby slowing down the progress of the science and technology surrounding functional foods.
Balanced Diet
It is well established that a person’s diet plays a significant role in overall health, as well as in preventing chronic health conditions and diseases. A balanced diet is defined as one that is evidence based, drawing on the recommendations of numerous dietary guidelines. A diet with adequate nutrients and also within a healthy landscape is considered a balanced diet. Dietary guidelines around the world recommend a balanced diet that incorporates a variety of fruits, vegetables, whole grains and whole grain products, dairy products, protein sources, and oils. In addition, a balanced diet should minimize added sugars, solid fats, and refined grains.
A balanced diet provides essential nutrients to help maintain healthy body functions and prevent chronic disease. Combine fruits, vegetables, whole grains, and dairy foods each day, including at mealtime. A balanced diet requires choosing nutrient dense foods such as lean protein, vegetables, whole grains, and healthy fats. Thus, a varied diet that includes foods from all food groups will help a person meet their nutritional needs. In contrast, some diets, such as those high in added sugars and fats, can lead to overconsumption, leading to undernutrition and weight gain, which can cause health problems such as obesity, heart disease, or poorly controlled diabetes. Maintaining an adequate nutritional status is essential since research shows that suboptimal diets and their associated undernutrition and obesity can contribute to chronic disease. Protein, vitamins, and minerals from the five food groups are needed for the normal growth, repair, and maintenance of body tissues. A balanced diet will also provide the energy needed for daily activities. Dietary advice to maintain body weight to preserve overall health is also valid. As new guidelines to support healthy eating are published, and people adopt new habits and customs, such as plant based, vegetarian, and vegan diets, dietary advice should continue to emphasize key principles for overall health. Individual nutrition practices should not change as long as they meet energy, nutrient, and food group needs. For example, vegetarians should plan their diet carefully and may need to take B12 and iron supplements. Individuals’ eating patterns are based on cultural and individual preferences. Therefore, registered dietitian nutritionists must personalize and adapt dietary advice to meet the unique needs of diverse populations. Nutrient dense foods offer the most nutrition for optimal calories. A balanced diet is decorated with a variety of dishes, each portion containing calorie appropriate amounts of nutrient dense healthy components such as fruits, vegetables, whole grains and whole grain products, dairy products, protein, and oils. A balanced diet can include enjoying treats now and then. Combine protein sources with whole grains and vegetables in your dishes. Compliance with the above criteria can provide an overall healthy diet.
Components of a Balanced Diet
The Eatwell Guide reflects the common principles for a balanced diet that optimizes our health and well-being. It sets out the overall balance of different food groups that we need to eat to meet our nutrient requirements, highlighting the types and proportions of food we should include in each meal across the day. A balanced diet includes adequate amounts of the macronutrients (carbohydrates including fiber, protein, and fat) and micronutrients required by the body. These macronutrients provide the energy calories needed by the body to perform functions. Micronutrients such as vitamins and minerals, however, do not provide energy, but they are essential for many bodily functions, such as bone health, immune function, and blood clotting. To gain all the benefits of a nutritious diet, it is important to include a balanced mix of the macronutrients and micronutrients. There are no recommended proportions of energy that should be obtained from each macronutrient, as personal needs vary based on factors such as age, sex, weight, height, and physical activity level. However, it is recommended that adults avoid consuming more than 35% of their total energy from fat and limit the consumption of free sugars to 5% of total energy. When it comes to creating balanced meals, it is recommended to include 2 servings of fruit, 5-6 servings of vegetables and legumes/beans, 6 servings of lean protein sources, 3 servings of dairy (or alternatives), and 6 servings of grains in our daily diet. Combining these guidelines provides us with a strong foundation for achieving a nutrient-rich diet. It is vital for children and young teens to work with a healthcare professional to verify individual nutrition needs.
Nutrition-related Health Issues
Poor nutrition can cause a variety of health problems. Obesity is a complex health crisis in high-income countries. At the same time, health coverage often lacks the necessary nutrients in low-income countries, particularly in children. Malnutrition is the term used to describe both loss and obesity, as they are closely interrelated. Food allergies are also an increasing issue, as they cannot be accurately predicted or even cured. A number of factors make some people more likely than others to be affected by it. The discrepancy in quality of life and dietary outcomes is attributed to racial, political, gender, sexual orientation, and socio-economic disparities. People with lower incomes have traditionally expended a lower portion of their income on meals with a higher nutritious content and are more inclined to resort to fast and other types of cheaper, less nutritious foods. In addition, mainstream grocery supply is less obtainable in various socially deprived areas. Food deserts is the term for that. Growing food costs, along with the overuse of the Internet for recreation, also play a role in lower-income regions. Education to live a balanced life is critically significant in public health interventions in order to be long-term as well as beneficial.
Long-lasting health problems that occur as a result of poor nutrition include cardiovascular diseases that are presently the leading cause of death in most developed societies. More dietary conditions such as diabetes and chronic systemic illness, as well as forms of stroke, are linked to at least some types. Type 2 diabetes is now recognized as an epidemic, and it has recently become an increasing global concern. Diets high in sugar, fats, and sophisticated carbohydrates, as well as an excessive intake of calories and emotional overeating, are linked to insulin resistance. The guideline for the management of Type 2 diabetes emphasizes the importance of nutrients and makes three main suggestions. An individualized diet adapted to the nutritional needs, metabolic factors, and personal likes or dislikes of patients should be prescribed to meet the target blood glucose and lipid standards to achieve the desired weight, but in a safe and sustainable way.
Obesity and Malnutrition
Today, the health of most populations is undermined by nutrition-related chronic diseases. Worldwide, an estimated 1.9 billion adults aged 18 years and older are overweight, of which over 650 million are obese. Contrary to these figures, every year about 2.8 million adults die as a result of being overweight or obese. Overweight and obesity are major risk factors for non-communicable diseases and have reached epidemic proportions worldwide. Overweight and obesity are defined as abnormal or excessive fat accumulation that presents a risk to health. A crude population measure of obesity is the body mass index (BMI), a person’s weight divided by the square of his or her height. A person with a BMI of 30 or more is generally considered obese. A person with a BMI equal to or more than 25 is considered overweight.
Obesity is about 100 times more prevalent today than it was at the turn of the 20th century, and in many parts of the world, it is rapidly replacing traditional forms of undernutrition. Malnutrition is, in fact, an umbrella term that may include undernutrition as well as overweight and obesity or diet-related non-communicable diseases including type 2 diabetes, cardiovascular diseases, certain types of cancer, and osteoarthritis. It also includes deficiencies, imbalances, and excesses of micronutrients. Furthermore, the prevalence of malnutrition — including undernutrition and overweight or obesity — is currently considered a major global challenge that requires immediate attention from various levels of leadership and action. Unlike undernutrition, overweight and obesity are affecting a growing number of people and have become an increasing public health problem. Moreover, it is glaringly apparent that vulnerable populations are at risk of malnourishment expressed as overweight and obesity. Current rates of overweight and obesity are more pronounced in more vulnerable groups, including Indigenous peoples, low-income populations, and those living in low- or middle-income countries.