Dietary Proteins

Dietary Proteins; which ones are recommended?

The foods we eat contain nutrients that provide energy and other things the body needs.
Most of the nutrients in food fall into three major groups; carbohydrates, fats and proteins and three minor groups; vitamins, minerals and water.

Proteins are amino acids which form the body’s building blocks. There are 20 different types; 12 of them (non-essential amino acids) produced by the body and the remaining 8 (essential amino acids) are not.

The body receives the essential amino acids from the protein foods we consume. For proteins to be beneficial to the body, all the essential amino acids must be present in the meal at the same time.

Functions of proteins

Protein is an important component of all body cells and tissues:

• Proteins aid the formation, growth, maintenance, repair and replacement of worn out or damaged body cells and tissues. E.g. muscles, blood cells, skin, hair, nails, teeth, bones, etc.
• Special proteins known as nucleic acids found in ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) transmit hereditary characteristics from parents to children.
• Other proteins, known as enzymes, play an important role in chemical reactions like digestion and metabolism.
• Proteins form an essential constituent of certain hormones like insulin.
• Proteins provide vital energy to the body.

NB: The body does not store amino acids, as it does in fats and carbohydrates, so needs a daily supply of amino acids to make new proteins.

Sources of protein

The two main sources are: animal and plant.

1. Animal source proteins / complete proteins
• The only source of protein that contains all the essential amino acids required by the human body in sufficient amounts, thus classified as complete protein. E.g. meats, poultry, eggs, milk, cheese, yoghurt, snails, fish and sea-food.
• Stick to the leanest cuts, like baked or grilled chicken and turkey without the skin, beef with the fat trimmed off or fish, and egg whites.
• The best animal protein choices are fish and poultry.
• Choose moderate portion sizes of animal proteins, and make it only an occasional part of your diet because they are usually higher in saturated fats.
• The bottom line is that it is important to pay attention to what comes along with your protein food choices.
2. Plant source proteins / incomplete proteins
• Plant proteins are incomplete proteins because unless well combined, a single source of plant protein cannot meet the recommended daily amount of essential amino acids.
• Plant / vegetable sources of proteins, such as beans, nuts, and whole grains, are excellent choices that offer healthy fiber, vitamins, and minerals.
• Nuts are also a great source of healthy proteins with healthy fat.
• Vegans may substitute for animal proteins with beans, nuts and grains such as soy quinoa and kasha (which are extremely high in proteins) or low-fat dairy products like low-fat yogurts, cottage cheese and skimmed milk.

Recommended Daily Amount (RDA) of proteins

The RDA of proteins differs according to age, gender and weight, however; a healthy diet should include 2 to 3 servings of lean protein each day. Chicken – 2 thighs; Meat – 2 to 3 matchbox sizes; Eggs-2 to 3 per week, Fish - 1 small or ½ palm size, Tuna-2-3 matchbox size, Anchovies (Keta school boys): 8-10 small sizes; Beans - 3 stewing spoons.

Babies need exclusive breastfeeding from birth to six months of age followed by a timely introduction of appropriate and nutritionally adequate complementary foods. Young children require adequate amounts of protein in their diets to prevent iron deficiency anemia.

Pregnant or lactating women should take additional protein to meet their daily needs and to prevent anemia, premature delivery, bleeding during child birth and low birth weight babies. Men need higher amounts of protein each day due to their typical higher muscle mass.

Adults should take in adequate amounts of protein necessary to repair worn out tissues. Vegans should mix plant proteins properly to get a complete protein.

Protein Deficiency Effects

In young children under five years, there is kwashiorkor with symptoms as follows

• Retarded growth
• Loss of hair
• Changes in hair colour
• Slow healing of wounds
• Poor digestibility
• Anemia
• Edema (draining of fluid from the blood into the tissues)
• Poor immunity

In pregnant women, there is anemia which may lead to:

• Bleeding during child birth
• Premature birth
• Underweight birth weight
• Stunted growth in early life

In general, there is poor health with symptoms of:

• Fatigue
• Irritability
• Reduced production of antibodies (poor immune system)
• Greater susceptibility to infection
• Slower recovery from disease
• Slower healing of wounds and burns
• A continued protein deficiency may eventually lead to anaemia and liver disease

Excessive intake of Proteins

• Excess proteins are usually converted to substances known as fatty acids, and stored in the fatty tissues.
• When necessary the body can convert proteins to glucose (a vital source of energy), the excess of which can also be converted to fat.
• Research suggests that; people who eat red meat have a higher risk of developing colon cancer, heart disease, and diabetes, and a higher risk of dying from heart disease, cancer, or any other cause.
• There's also substantial evidence that; replacing red meat with fish, poultry, beans, or nuts, could help prevent heart disease and diabetes and lower the risk of early death.

Conclusion

• Eat red meat (beef, pork, lamb, etc.) occasionally. Not more than two 3-ounce servings a week.
• Skip processed meats. They are high in sodium and strongly linked to the risk of cancer, heart disease, and diabetes.
• Get a good mix of proteins. Almost any reasonable diet will give you enough proteins each day. Eating a variety of foods will ensure that you get all of the essential amino acids you need in their right quantities.
• Pay attention to the protein package. You will not get pure protein. Some proteins come packaged with healthful fiber and micronutrients, such as beans, nuts, and whole grains. Others with fat and/or high salt like some processed meats
• Balance carbohydrates and protein. Cutting back on highly processed carbohydrates and increasing healthy protein intake keeps you full for long, improves the level of blood triglycerides and HDL, and so may reduce your chances of having a heart attack, stroke, or other forms of cardiovascular diseases.

NB: Add some soy to your meals if tolerable. Soybeans, tofu, and other soy-based foods are an excellent alternative to red meat: about 2 to 4 servings per week are adequate. Soy has a high concentration of isoflavones, a type of plant-made estrogen (phytoestrogen) thus known to;

• Lower cholesterol, chills and hot flashes
• Prevent breast and prostate cancers
• Aid weight loss
• Ward off osteoporosis

References:

1. Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids (macronutrients). National Academy Press.
2. Harvard School of Public Health Nutrition Source
3. WHO dietary and physical activity guidelines for Ghana, Ministry of Health, December 2009.