The Role of Major Nutrients Across the Stages of Human Life Spans

The role of the major nutrients such as carbohydrates, fat and protein across the stages of human life span
Anthony Salvucci 8 October 2012
Introduction
Many of us believe that our lives consist of a beginning, middle, and, finally, an end. However, many of us may not recognize that there are several other degrees of life that we must pass through. The human life cycle starts at conception and continues until death. As we move through the different stages of life, our nutritional requirements continually change and, as we mature, our bodies require more of some nutrients and less of others. The nutritional needs of an infant differ from those of an adult and the nutrients required by a pregnant or lactating woman differ from those required by a 60 year old man. Infancy, adolescence, pregnancy, lactation, menopause, and aging place unique nutritional demands on the body. To maintain a healthy life, a balanced diet of carbohydrates, proteins, fats and oils, minerals, vitamins, and water are required. But, how much of each of these nutrients are needed by the human body? The Institute of Medicine has published recommendations for Dietary Reference Intakes (DRIs)¹ that are age specific for the various stages of life. However, the DRIs are not applicable for individuals who suffer from chronic illness or for those who are at high risk for illness due to age, genetics, or lifestyle choices such as smoking, alcohol intake, drug use, and strenuous exercise or activity. Health care providers and clinicians must determine nutritional requirements in such cases based on a patient 's health history and available information.
Nutrients
Surprisingly, our bodies requires the same nutrients throughout our lifespan. However, the quantity of nutrients and calories required by the human body will vary and change depending on age and gender, as well as health. Pregnancy and lactation also effect the nutrients and calories necessary to maintain a healthy lifestyle. The human body must have nutrients to function. The nutrients essential for the human body are proteins, carbohydrates, fats and oils, minerals, vitamins, and water. They are provided by eating a balanced diet of whole grains, vegetables, fruits, beans, and proteins such as meat and fish.
Proteins Proteins consist of amino acids, small units necessary for growth and tissue repair. Except for water, and possibly fat, proteins are the body 's most plentiful substance. Animal foods rich in protein consist of milk, eggs, poultry, fish, and meat. Excellent plant sources of protein are cereals, breads, beans, nuts, and peas.
Carbohydrates The main source of the body 's energy is provided by carbohydrates consisting of starches and sugars. Carbohydrates account for approximately fifty percent of the calorie intake for Americans and as much as four fifths of the calories in the diets of Africans and Asians. Foods rich in carbohydrates, such as potatoes, corn, wheat, and rice, are also a main source of protein for most of the world 's populations.
Sugars provide energy (calories) but have no nutritional value and are called empty calorie food.

Fats and Oils
Fats and oils, referred to as liquid fats, are concentrated sources of energy. The human body requires fats in the diet for good health. They provide certain vitamins as well as cushioning for vital organs. They make up a portion of all cells in the body and help maintain body temperature. Since foods containing fat remain in the stomach longer, they help delay hunger pangs.

Minerals
Minerals are neither vegetable nor animal. They are inorganic. Nearly all foods contain minerals of some sort and contribute to a varied intake of minerals essential for a healthy body. Calcium builds bones and teeth and is essential for blood clotting. It is needed at all stages of life. The best sources of calcium are hard cheese and milk as well as nuts, leafy greens, and small fish, such as sardines where the bones can be eaten. Phosphorous works with calcium to make bones and teeth strong. Iron is one mineral that may need to be supplemented in children under the age of 4 and adolescent girls, as well as women in their childbearing years. These groups require more iron than may be provided in a normal diet. Iron is necessary to build red blood cells and helps blood carry oxygen from the lungs to each body cell. Meat, especially liver, dark green vegetables, and egg yolks are excellent sources of iron. Other minerals that are necessary for a healthy body are sodium, iodine, magnesium, zinc, and copper.

Vitamins
Vitamins play a crucial role in the normal growth, functioning, and metabolic processes within the human body throughout the life cycle. They consist of chemical compounds that function as antioxidants, mediators for cell generation, and tissue growth, Some vitamins are crucial for metabolic reactions that result in the release of energy from carbohydrates, fats, and proteins. The thirteen vitamins can be broken down into two groups. The nine water-soluble vitamins consist of the B vitamins and vitamin C. The four fat-soluble vitamins consist of A, D, E, and K. These two vitamin groups are different in many ways. Water soluble vitamins are destroyed much faster during cooking or heating, causing them to become depleted more rapidly in the body which may lead to a vitamin deficiency if not replenished. Fat-soluble vitamins, conversely, remain in the body longer and can lead to excessive, even toxic, levels. Other factors that may contribute to vitamin deficiencies include disease, drug interactions, pregnancy, and newborn development.

Water
Water is a vital necessity to the well being and health of all human beings throughout the life cycle from infancy through old age. It is instrumental in the distribution and absorption of nutrients such as carbohydrates, proteins, and other essential elements throughout the body. Water is a protective lubricant for all parts of the body and its presence in and around the body 's tissues as well as the brain, eyes, spinal cord, and other critical parts. Water is also helpful for the smooth movement of bone joints. The water that is present in the mucous and salivary juices of our digestive system are necessary to move food through the digestive tract. A less attractive requirement that the body has for water is the transport and removal of body waste.
Infancy:
It may be surprising to learn that, during its first year of life, an infant will require a proportionately higher amount of nutrients per pound than will be required over the rest of its life cycle. This is primarily because an infant grows rapidly and experiences a number of physiological changes such as cell division during this growth period. Infants usually double their length and triple their weight between birth and one year of age.² These physiological changes include the maturation of its mouth, tongue, and digestive tract. As these changes take place the infant 's feeding habits and needs will also change. From being limited to suckling and taking in only liquid nutrients such as breast milk or formula the infant will advance to the ability to chew and swallow semi-solid foods, such as strained vegetables, fruits, cereals,and meat. As the infant grows, the introduction of solid foods such as those consumed by adolescents and adults can be introduced into its diet. During this time of transformation, the infant will begin to gain dexterity and the ability to feed themselves. Their feeding habits and nutritional needs will continually change. By providing infants and babies with a variety of healthy and nutritious foods, as well as a positive and supporting feeding environment, they will learn to enjoy new tastes and textures and will develop healthy eating habits.
Adolescence and Adulthood:

The Institute of Medicine recommends higher intakes of protein and energy for development and growth in adolescents.³ Recommendations for most micro-nutrients are the same as for adults with the exception of certain minerals necessary for bone growth including calcium and phosphorus. These recommendations, however, are controversial since there is no clear evidence that higher intakes of these minerals are necessary for bone growth. There is clearer evidence that calcium is increased with exercise. Weight gain as well as atherosclerosis often begin during adolescence and young adulthood. making it important for those in these age groups to establish healthy eating and lifestyle habits to reduce the risk of chronic diseases later in adulthood.

Pregnancy:

When a woman becomes pregnant she is no longer responsible only for her own health. She is now responsible for the well-being of the fetus developing in her body. The nutrients a fetus receives is totally dependent on what the mother eats. The nutrients that a woman absorbs during pregnancy can have a profound and lasting effect on the fetus and future health of the infant. For a fetus to develop normally it must receive the necessary nutrients in the proper quantities and at the correct times. it 's only source for these nutrients is its mother. A pregnant woman 's body has a natural ability to compensate for nutritional deficiencies. However, the mother can not provide the proper nutrients for the fetus if she herself is deficient in them. If the fetus is deprived of essential nutrients it may suffer health problems later in the pregnancy and into infancy and childhood. Pregnant and lactating women have increased requirements for both macro-nutrients ( carbohydrates, proteins, fat)and micro-nutrients (vitamins and minerals). The failure to maintain required intakes of these vital nutrients may increase the risk of certain chronic health problems in their children, which may manifest themselves many years later.

Lactation:

Breast milk and infant formula will both help an infant grow. Breast milk, however, is the best choice according to the American Academy of Pediatrics and the American Dietetic Association. Breast milk provides the baby natural defenses against infections, as well as allergies.4 Colostrum, the milk that is produced during the first several days, contains a large amount of infection fighting antibodies. The American Academy of Pediatrics, the American Dietetic Association and other health organizations recommend breastfeeding or nursing, exclusively during the first six months of a baby 's life. They recommend the addition of complimentary foods to the baby 's diet when it is ready and the continuation of breastfeeding until the baby is at least six months old. Unfortunately, in the United States, only 15% of white mothers, 13% of Hispanic Mothers, and 10% of African-American mothers follow the recommendation to breastfeed their babies, exclusively, for the fist six months.³

Later Life and Seniors:

Elderly people generally experience a reduction in physical activity, lean body mass, and metabolic rate as they age and require less energy than younger adults. Nutrients required by the elderly are different from those needed by younger adults. For example, the need for vitamin D is increased in order to reduce age related bone loss and risk of fracture. Also, the nutritional needs of older men and women differ. Older women require less iron because of iron conservation as well as decreased iron loss in postmenopausal women but require additional calcium to support bone density. While energy requirements for most seniors decrease, the need for protein, vitamins, and mineral requirements do not. Seniors should maintain a healthy diet of nutrient dense foods like colorful fruits and vegetables, whole grain breads, and low fat of nonfat dairy foods, as well as lean meats and fish.

Conclusion:
Our nutritional requirements vary throughout each stage of our lives. It is important that our bodies are supplied with the proper diet for development and health. Before an infant is born it must depend on its mother to provide it with the necessary nutrients for proper growth and development. From birth, through childhood and adolescence, and even into adulthood, what we eat determines brain development, physical growth, sexual maturation, resistance to disease, and overall health. Good nutrition is vital for older and senior adults to maintain optimum health. As the body matures and ages, tissues and organs begin to deteriorate and function less efficiently Proper nutrition prevents or slows these symptoms of age and provides a better quality of life. Of course, there are outside influences that influence our diet, such as economics, as we may not financially be able to obtain the proper foods. Peer pressure and social mores among teenagers can also influence diets. As a general rule adults are much more likely to maintain a balanced and proper diet. But, for each of us the overall importance of age-appropriate nutrients can not be overstated. They are vitally necessary for us to develop and maintain a healthy body and lifestyle.

References:
1. Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrates, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients). Washington, D.C.: National Academics Press, 2005.
2. Jay L. Hoecker, MD. How Much Should I Expect My Child To Grow In The First Year? Mayo Clinic Department of Infant and Toddler Health.
3. Lanou AJ, Berkow SE, Barnard ND. Calcium, dairy products, and bone health in children andyoung adults: a reevaluation of the evidence. Pediatrics. 2005; 115:736-743.
4. Haliena, Rita. Why is Breastfeeding Good for Your Baby? Clemson University Department of Food Science and Human Nutrition and EFNEP. Nutrition Information & Resource Center (NIRC). Nourishing News (08/03).

References: 1. Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrates, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients). Washington, D.C.: National Academics Press, 2005. 2. Jay L. Hoecker, MD. How Much Should I Expect My Child To Grow In The First Year? Mayo Clinic Department of Infant and Toddler Health. 3. Lanou AJ, Berkow SE, Barnard ND. Calcium, dairy products, and bone health in children andyoung adults: a reevaluation of the evidence. Pediatrics. 2005; 115:736-743. 4. Haliena, Rita. Why is Breastfeeding Good for Your Baby? Clemson University Department of Food Science and Human Nutrition and EFNEP. Nutrition Information & Resource Center (NIRC). Nourishing News (08/03).