We are all familiar with the saying- you are what you eat. But we often take this for granted. There is no doubt that good nutrition and regular exercise are crucial for optimal body functioning and for maintaining health and wellness. So, what is good nutrition and what are the best nutrition tips to stay healthy?
What is Nutrition?
Nutrition is the sum of what we consume daily and how our body utilizes it. What we consume contain substances called nutrients, that are required for normal body functioning like growth, metabolism and tissue maintenance. These nutrients include proteins, carbohydrates, lipids, fiber, vitamins, minerals and of course water. Good nutrition is therefore one that contains a balance of the different nutritional components. For example, consuming excess lipids over time can lead to deposition in the blood vessels leading to risk of hypertension, heart disease or stroke. For this reason, the United States Ministry of Health and the Canadian Ministry of Health both recommend consuming daily balanced diet that contain approximately 50 percent of fruits and vegetables, 25 percent of proteins and 25 percent of carbohydrates. Now we will discuss these nutrients in more detail.
Macronutrients and micronutrients
Generally nutrients are classified into macronutrients and micronutrients. Macronutrients are required in large amount by the body and constitute a larger proportion of what we consume. They include carbohydrates, protein and lipids. While, micronutrients are only required in small amounts. They include vitamins and minerals.
Carbohydrates contain the three elements, carbon, hydrogen and oxygen. They occur in either simple or complex forms and are derived from both plant and animal sources. Simple carbohydrates contain one or two carbohydrate molecules known as sugars. An example of simple sugar is glucose which is found in a variety of sweet food sources like fruits. Another example is galactose which is found in milk. Simple sugars are often added to processed foods like iced cream, cookies and soft drinks to improve their taste.
Complex carbohydrates on the other hand contain several carbohydrate molecules in varying complex arrangements. A common complex carbohydrate is starch which is contained in foods like cereal, potato, bread and flour. Another form of complex carbohydrate is fiber, which is not digested by the body but acts as roughage. This form of carbohydrate is found in vegetables, fruit skin and wheat bran.
Functions of carbohydrates in the body
Fibers form the undigested component of carbohydrates and act as roughage. They increase stool bulk and stool passage through the digestive tract. Other carbohydrates are broken down in the digestive tract into simple sugars like glucose and fructose. These simple sugars are the primary source of energy or calorie for the body. They are utilized by muscle cells during exercise and brain cells during various activities performed by the brain.
Most of the sugar derived from the diet are stored in the liver and muscle cells from where they are gradually released for delivery to other cells. Excess sugar is however converted to fat and stored. Excessive storage of fat is harmful to the body, as it is associated with numerous conditions like heart disease, diabetes, hypertension, cancer and stroke. Therefore, it is important that carbohydrate should not be more than 25 percent of our diet.
Most lipids contain the three elements carbon, hydrogen and oxygen, while others contain phosphate in addition. Lipids occur in various forms like fats, phospholipids and sterols. Fats or triglycerides constitute over 90 percent of body lipids. They are made up of fatty acids and glycerol. The fatty acids are either saturated or unsaturated. Saturated fats have no double bonds attached to the carbon atoms and are usually found in animal products like meat, butter, and some plant products like coconut oil and palm oil.
Unsaturated fats have one or more double bonds attached to the carbon atoms, and are usually found in plant products like vegetable oils, cod liver oil and some animal products like cold water fish. During some commercial food processing, unsaturated fats are artificially converted to saturated fats leading to formation of trans fatty acids. These trans fatty acids are found in margarine, cookies, muffins, doughnuts and fries. Trans fatty acids contain a higher content of cholesterol which is associated with higher risk of heart disease, hypertension and stroke. However, the concentration of trans fatty acids in these products vary.
Phospholipids on the other hand are important components of the membranes of all cells in the body. They are found in eggs, liver and peanuts. While cholesterol is an important component of bile which is required for absorption of lipids from the diet. It is also found in cell membranes and it forms an important component of hormones which help to regulate the body functions. Cholesterol found in the body are bound to phospholipids to form lipoproteins. These lipoproteins occur in two main forms based on the amount of bound phospholipids. Low density lipoproteins or LDL contain lower proportion of phospholipids and higher proportion of cholesterol. High levels of these LDLs are associated with increased risk of heart diseases, hypertension and stroke. While high density lipoproteins or HDL contain higher proportion of phospholipids with lower proportion of cholesterol. High level of HDL is protective against heart disease, hypertension and stroke.
Functions of lipids in the body
Most lipids in the diet are broken down to fatty acids and glycerol. Some are converted to carbohydrate molecules and used for energy. Others are converted to amino acids which are components of proteins, while others are used for synthesizing more lipids. Other lipids in the diet are transported with the cholesterol released from bile for synthesis of more cholesterol and phospholipids. These are further used for formation of cell membranes and for storage of other lipid soluble nutrients like vitamin A, D, E and K. Excess lipids are stored in the liver and fatty tissues beneath the skin.
Some unsaturated fats play important role in reducing cholesterol in the body thereby helping to reduce the risk of hypertension and heart disease. They include Omeg-3 and Omega-6 fatty acids found in canola oil, sunflower oil, corn oil, walnut, cottonseed oil, soybean oil, flax, eggs, cold water fish like tuna, sardines and albacore. It is recommended to limit intake of fatty foods especially saturated fats and trans fat, due to their adverse health effects. This means boiling, grilling or baking food instead of frying. High fat is found in poultry skin, fatty beef, high fat dairy like cheese, butter and whole milk. Thus, these foods should be limited in our diets. However saturated fats like omega 3 are beneficial.
Proteins are composed of amino acids which contain the five elements carbon, hydrogen, oxygen, phosphate and nitrogen. Some of these amino acids are called essential amino acids because they must be consumed in the diet. While others can be synthesized from other nutrients like carbohydrates, lipids and other amino acids. A good diet should therefore contain all the essential amino acids.
Animal products like meat, fish and dairy are rich sources of all the essential amino acids. whereas, most plants contain incomplete amounts of the essential amino acids. To obtain the complete set of amino acids from plants, they have to be combined in the diet. For example combination of corn and beans in the diet will provide the complete set of the essential amino acids.
Protein functions in the body
Proteins are broken down in the body into amino acids and transported to cells of the body for synthesis. Proteins in the body have several functions. They are important components of the body cell structure. They are also important for transporting substances in the blood and tissues.
Furthermore, proteins form hormones which regulate body functions, and they are important for regulation of body water and electrolytes. Rich sources of protein include lean meat, poultry, eggs, legumes, nuts, sea foods, seeds and soy products. Excess protein in the body can also be converted to carbohydrates and lipids.
Vitamins and their functions
Vitamins are organic substances needed in small amount by the body but cannot be synthesized by the body. They are crucial for catalyzing or facilitating several metabolic reactions in the body. Their absence from the diet results in several metabolic disorders. There are broadly two groups of vitamins, namely fat soluble and water-soluble.
Fat soluble vitamins include vitamins A, D, E and K. They can be stored in small amounts in the body but are required in daily diet. Vitamin A is contained in the pigment of the eyes and are required for normal vision. Vitamin D is necessary for absorption of calcium from the digestive tract, and this is required for bone strength and development. Vitamin E is important for normal fertility and has antioxidant function. While vitamin K is required for normal clothing of blood.
The water-soluble vitamins are vitamins B and C. They cannot be stored in the body and thus must be present in the diet daily. Vitamin B is a complex of several vitamins that catalyze several metabolic reactions and supports several body systems. While vitamin C is important for maintaining the connective tissues and also has antioxidant function. Fruits and vegetables are rich sources of vitamins.
Minerals and their functions
Minerals are also required in small amounts which cannot be synthesized by the body. Calcium and phosphorus constitute about 80% of the entire minerals in the body. Others are sodium, chloride, magnesium, Sulfur, zinc, iron, manganese, iodine, fluoride, copper, selenium and chromium.
These minerals have a variety of functions and their absence in the diet results in deficiency disorders. For example iron is a component of the red blood cells and deficiency results in anemia. Calcium is a component of bones, muscles and nerves, and its deficiency result in bone weakness, muscle weakness and poor nerve conduction. Fruits, vegetables and low fat dairy like milk, cheese and yogurt are rich sources of minerals. Some minerals are however harmful in excess amounts. For example, excess sodium is associated with fluid retention in the body and subsequently risk of hypertension.
The above is a simple guide to healthy nutrition. However, it is important to add that some individuals may require special diets due to a medical condition. For example diabetics require low carbohydrate diet due to insulin deficiency. Please consult your doctor or dietitian if you require a special diet. On the other hand food fad diets are prevalent. These should be avoided as they are often difficult to maintain on the long run, and may actually be harmful to your health.
Finally it is true that switching from the eating habit we are already used to, is not an easy step. However, this can be done. It is best to start by making small, gradual changes and eating a variety of healthy foods rather than trying to take a giant leap. In addition, it is good to keep track of what we eat daily by writing it down. This will make it easier for us to assess our diet and subsequently make the necessary changes.
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