Have you ever wondered what exactly constitutes a healthy diet?
Messages about healthy eating have been around for decades.
Dietitians and health professionals have been promoting a consistent message about the types of food we should consume more of, or not in.
- Recommended Guidelines For A Healthy Lifestyle
- What Constitutes A Good Diet?
- Why Is A Healthy Diet Important?
- What Is Nutrition?
- What Are The Classes Of Nutrients?
- Carbohydrates (45% – 65%)
- Proteins (10 – 35%)
- Fats (15 – 30%)
- Water – 6 to 8 glasses (230 ml) for adults
- Your Next Steps
Recommended Guidelines For A Healthy Lifestyle
Eat a variety of nutrient-rich foods.
Maintain a healthy weight.
Choose lots of fruits, vegetables and grains.
Choose a diet low in fat, especially saturated fat and cholesterol.
Use sugars only in moderation.
If you smoke, do so as infrequently as possible, and eventually quit.
What Constitutes A Good Diet?
It is one that consists of proteins, carbohydrates (sugar and starches), fats, vitamins and minerals in the right proportions.
Your body needs a regular supply of these nutrients to grow, replace worn-out tissues and provide energy.
Balance, variety, moderation and adequacy are key to maintaining good health.
Balance means eating the recommended number of servings from each food group on most days.
Variety within each food group (for example, eating different fruits from the fruit group instead of only eating apples) ensures that you get all the nutrients you need, since no single food provides all nutrients.
Eating a wide variety of foods will also help you avoid eating too much of any substance that may be harmful.
Moderation means eating a little of everything but nothing in excess.
Adequacy means are you having enough of a specific nutrient in your diet.
There is no such thing as good or bad food.
There are only good and bad diets.
All types of food can fit in a healthy diet if you eat everything in moderation. (3)
Why Is A Healthy Diet Important?
By keeping a healthy diet, we can maintain a healthy body weight and reduce our risk of developing diet-related diseases such as heart disease and cancer. (4)
However, maintaining a healthy diet is not as straightforward as it may seem.
There is much confusion among the general public about what constitutes a healthy diet, as well as a belief by many that they are already keeping a healthy diet.
71% of people agree with the statement “I do not need to make changes to the food I eat, it is already healthy enough”. (5)
A healthy diet and lifestyle in adulthood aims to:
Ensure that you are fit, healthy and full of vitality in the short term.
Minimize the risk of chronic diseases such as coronary heart disease, stroke, diabetes, cancer and osteoporosis in the long term. (6)
What Is Nutrition?
It refers to the role that food plays in relation to the well-being of the human body.
The food we eat can have a huge impact on our health and well-being. (7)
Hence, a balanced, nutritional diet is one that provides all the essential nutrients in the right quantities for health.
In fact, it is important to understand that the science of nutrition is still in its infancy.
Centuries ago, scientists were busy discovering new stars and galaxies while the first vitamins were only discovered decades ago! (8)
Nutritional knowledge changes constantly.
If you follow the news, you will notice that certain types of food come into and go out of favour with nutritionists and doctors alike.
It is fair to say that nutrition is an evolving science and those who study nutrition are pioneers of a new frontier.
From what science has shown us to date, we know that everyone needs about 45 different nutrients to stay healthy. (9)
What Are The Classes Of Nutrients?
Since no single food supplies all the nutrients needed for an adequate diet, consumption of a variety of food is necessary.
An adequate diet is one that supplies us with enough food to sustain life while promoting growth and good health.
The quality and quantity of food that we give ourselves will determine whether we have a balanced diet.
For sufficient nutrient intake, a balanced diet should contain no fewer than 1200 calories per day for adult women and no fewer than 1800 calories for adult men. (10)
What Are Calories?
A calorie is a measurement of the energy that food supplies to the body. Each type of energy-providing nutrient provides a different amount of calories.
Protein – 4 calories / gram
Carbohydrates – 4 calories / gram
Fats – 9 calories / gram (11)
3 of the major macronutrients are carbohydrates, proteins and fats.
A healthy diet that provides our body with the best macronutrient balance can be found below:
Carbohydrates – 45% – 65%
Proteins – 10% – 35%
Fats – 20% – 35% (12)
Carbohydrates (45% – 65%)
Carbohydrates is the primary source of fuel for energy and heat in the body.
They are the body’s most efficient energy source, ensuring that our brain, muscles, and other organs run smoothly.
They consist of simple carbohydrates like sugar and fruits, and complex carbohydrates like starches and fiber (e.g. pasta, rice, bread, and vegetables).
It is suggested that you get most of your carbohydrate from complex sources.
What Are Simple Carbohydrates?
Simple carbohydrates are sugars such as glucose, fructose, lactose and sucrose.
Sources include corn syrup, maple syrup, table sugar, candy, cake and sweetened cereals.
They contribute “empty calories” that provide energy but no nutrients.
What Are Complex Carbs?
The main source of complex carbs are wholegrains and wholegrain products such as wholewheat bread, brown rice, pasta, vegetables and beans.
Complex carbohydrates usually supply a healthy bonus of vitamins, minerals and fiber.
Each type of carbohydrate will eventually end up as glucose (a form of sugar that is carried in the blood and transferred to cells for energy).
But, they differ at the rate in which they enter the blood stream and in their nutritional value.
Simple carbohydrates are usually low in nutritional value and enter the blood stream quickly, providing short-lived energy.
Complex carbohydrates enter the blood stream in a slower, more consistent rate and are more nutritious, with dietary fiber, vitamins and minerals. (13, 14)
What counts as a serving?
(rice, bread and noodles)
½ cup of rice/mee/mee-hoon/kuay-teow
1 slice of wholemeal bread
½ piece of chappati
1 cup of porridge
½ cup of breakfast cereal
½ cup of green leafy vegetables (cooked)
½ cup of tubers
1 slice of papaya/water-melon/pineapple
½ cup of fruit juice
Milk and dairy products
1 glass of milk
1 cup of yogurt
1 slice of cheese
Eggs, meat, fish and nuts
1 medium-sized chicken drumstick
1 mackerel (ikan kembong)
2 matchbox-sized lean meat
1 cup of nuts
2 pieces of beancurd
2 pieces of tempeh (fermented beans) (15)
Proteins (10 – 35%)
Protein is a part of every cell in your body.
Tissue building is the primary function of protein.
It is an important structural component that’s needed for the formation of cells in your bones, nails, hair and skin.
An important raw material needed for your body to make enzymes which are essential for its proper functioning, digestion and reproduction.
It is involved in the production of neurotransmitters, which influences your mood and mind.
Protein is also one of the base materials needed in the immune system. (16)
Life is not possible without protein in your body.
The human body is a superb package of more than 100,000 different proteins. (17)
Since our body is not capable of manufacturing protein, it has to be consumed from our diet on a daily basis to replace the loss ones.
Did you know?
Protein is considered the substance of life?
The word “protein” originates from a Greek word meaning “first place”. (18)
Water is the most plentiful substance in the body.
Second is protein.
It makes up about 15% to 20% of our body weight. (19)
In fact, 50% of the body’s dry weight (not including water) is protein, and there are 100,000 of different proteins, each with special functions. (20)
Why Do You Need Protein?
You need protein for a number of reasons:
Defense and Immunity
Protein is a major component of leucocytes, or white blood cells, which act against bacteria.
Therefore, protein is essential to help fight infection and illnesses.
It is also needed in the formation of antibodies, which increase our immunity to foreign bodies.
Healthy Skin and Hair
90% of our hair and skin tissue is protein.
Lack of protein will show up in brittle, fragile hair strands and wrinkled skin.
Enzymes, which are responsible for converting food into energy, are constructed from protein.
They are also catalysts for chemical reactions.
Protein, therefore, has a direct influence on the amount of energy you have.
It is also the basic material in hormones, which, among other things, impacts our blood sugar levels and metabolic rates.
Growth and Maintenance
Protein is vital to the development of new and replacement tissues.
For example, for wounds to heal after a burn or injury, or hair to grow after a trim at the salon, cells and tissues cannot be replaced without protein.
Protein is responsible for regulating the level of certain substances within the body, namely water.
As it attracts water, protein helps maintain fluid balance in cells.
It also helps transport materials such as salt, potassium and electrolytes, in and out of cells.
A Blood Component
Protein is an important part of red blood cells and plasma, which are essential blood components.
It is also necessary for the formation of new red blood cells (which have a lifespan of approximately 3 to 4 months).
In order to perform all these tasks, proteins that are eaten must first be digested or broken down into the smaller units called amino acids. (16)
The Building Blocks of Protein
Although they perform many diverse functions, proteins in all living tissue regardless of their source (animal or plant) are made of 20 different kinds of amino acids, which serves as biochemical building blocks. (21)
The only difference between different proteins is the number, type and sequence of the amino acids present in the protein chains, as well as the structural configurations.
Amino acids have the same relationship to proteins as alphabets have to words.
Just as alphabets combine to form thousands of words, amino acids combine to make thousands of combinations of cell materials, tissues, enzymes, hormones or other active components.
Essential and Non-Essential Amino Acids
The body absorbs protein from food, breaks it down, and reconstructs many of the amino acids.
Of the 20 known amino acids, 9 are called “essential amino acids” because they cannot be synthesized in sufficient quantities in the body.
Essential amino acids must be obtained from the food that we eat.
The nine essential amino acids are histidine, methionine, threonine, tryptophan, leucine, isoleucine, lysine, valine and phenylalanine.
It is not necessary for you to memorize this entire list of amino acids. 🙂
If you eat “complete” proteins, you will have all the essential amino acids you need.
Histidine and arginine are also essential for infants growth.
Since essential amino acids are not stored in the body, sources of protein containing them must be included in your daily diets.
To build the proteins needed for maintenance and growth, all the essential amino acids must be present at the same time.
If even one is absent or present in too small an amount, this deficiency will limit the utilization of the other amino acids.
The amino acid which is deficient is known as the “limiting” amino acid, and the principal limiting amino acids are methionine, tryptophan and lysine.
It is also possible that an excess of one amino acid may reduce the utilization of another amino acid.
Thus, a deficiency occurs.
Amino acids cannot be stored for use later on.
Instead, they are oxidized and the nitrogen portion is excreted, chiefly as urea.
The carbon, hydrogen and oxygen fragments that are left are used to provide energy or are converted into fat.
The body does not utilize the energy available in protein unless the other sources of energy (carbohydrates and fats) have already depleted. (22)
“Complete” and “Incomplete” Proteins
Food containing all nine of the essential amino acids and many of the non-essential ones are called “complete” proteins.
Those that have essential amino acids in the right proportions are considered to have high biological value.
“Incomplete” proteins, called low biological value food, on the other hand, usually lack one or more of the key amino acids.
Meat, fish, eggs and dairy products are examples of complete protein sources.
Plant food such as vegetables, fruits, nuts and grains are examples of incomplete protein sources.
Preferred complete protein sources include lean meat, poultry, seafood, skim milk, egg whites, legumes, wholegrain and soy products.
Liver, whole eggs, whole milk, and most cheeses are also good protein sources, but they should be eaten less frequently, because of their saturated fat and cholesterol content.
A healthy diet requires that we get an adequate amount of “complete” protein without extra fat and cholesterol.
In most cases, poultry and fish have lower fat and cholesterol content than fatty red meat like beef and mutton.
So, a healthy diet demands a balanced combination of animal protein sources such as lean meat and poultry, mixed with plant protein sources such as beans, rice or cereals.
Protein from plants such as vegetables, grains, beans, peas and lentils, lack one or more essential amino acids, and are considered incomplete proteins.
However, by combining plant protein from different sources, such as rice with beans or seeds, you can ensure that all the essential amino acids are consumed. (23)
How Much Protein Do You Need?
Protein should account for about 15% of our daily calories and ideally from protein sources that are low in fat.
Protein requirements vary from person to person depending on individual lean body mass, physical activity, life-stage and age.
Recommended protein intake:
Source: Food and Nutrition Board, National Research Council, National Academy of Sciences, 10th ed., 1989, National Academy. Press: Washington, DC.
Examples of food and their relative value:
Protein content per 100 g
|Food||Protein Content (g)||Kcal||Energy from Protein (Kcal)|
Source: Nutrition Facts Desk Reference by Dr. Art Ulene.
At first glance, it may seem that animal sources of protein would be superior because of the higher concentration of protein.
However, the body cannot distinguish the source of protein nor the concentration – only the total amount.
Meat may be a good protein source but during production, other substances are added to it.
For example, antibiotics, hormones, pesticides and herbicides have been found in cattle and pig feed.
Milk is also said to be a good source of protein, but the problems often associated with pasteurization and milk products make it a less than desirable source.
As it turns out, soy protein has gained much reputation as a good protein source and has proven to have health benefits.
Furthermore, soy protein comes without the heavy load of fat that is present in meat, eggs and milk.
Soy protein can also be the alternative for those who are allergic to milk and milk products (lactose intolerant), and to those who prefer protein from non-animal sources (vegetarians).
Soy contains phytochemicals known as isoflavones, which may play a role in lowering risks for diseases. (24)
Is Your Protein of Good Quality?
It is easy to measure the amount of protein present in food, but measuring the quality of protein – the types and quality of essential amino acids present can be rather complicated.
One way to estimate the quality of protein is to analyze the essential amino acids and then compare the result to a standard amino acid profile developed by the Food and Agriculture Organization (FAO) and the World Health Organization (WHO).
This standardized profile is recognized throughout the world.
The most common biological method of protein comparison is the Protein Efficiency Ratio (PER).
The test protein is compared to milk protein (casein) which has a PER of 2.5.
So, any protein with a PER of 2.5 or above is considered a high-quality protein.
Another method, the Biological Value (BV) is more accurate than the PER, but is more tedious to perform.
One other factor that is important in determining protein quality is the digestibility of the protein – called Protein Digestibility Corrected Amino Acid Score (PDCAAS).
Source: World Health Organization
The World Health Organization (WHO) now uses this new evaluation method to rate the amino acid of the protein, plus a rating of its digestibility by humans. (22)
Fats (15 – 30%)
Although we hear a lot of negative comments about “fat”, the truth is that the body NEEDS a certain amount of fat to work properly.
Fat is part of every cell.
Excess energy is stored in the form of fats.
Fats are also necessary for transportation and storage of the fat-soluble vitamins A, D, E and K.
It supplies the body with essential fatty acids necessary for proper growth and healthy skin.
Fats are a more concentrated fuel than carbohydrates and supply 9 kilocalories (38 kJ) of energy per gram.
Types of Fats
They are divided into 2 groups: saturated and unsaturated
The body obtains fat from both animal and plant sources.
Although we need a certain amount of fat to be healthy, it is important to understand the kinds of fat that are most beneficial.
Unsaturated fats is a healthier alternative to saturated fat and can be found in vegetable oils such as sesame, sunflower, soy and olive; and in oily fish such as mackerel, sardines and salmon.
Unsaturated means that the fat is usually liquid at room temperature and generally comes from vegetable sources.
Monounsaturated and polyunsaturated fats are both included in this group.
Saturated fats should be your last choice.
Limit your intake of these fats because high intakes may be associated with increased risk of heart disease.
Saturated means that the fat is generally solid at room temperature and is usually from animal sources.
Found in lard, butter, hard margarine, cheese and full cream milk.
It is also the white fat you see on red meat and underneath poultry skin.
Did you know?
In reality, many foods contain both saturated and unsaturated fats, but they are described as one or the other depending on what they contain the most of.
So, even olive oil contains saturated fat too.
Trans fatty acids are found in various types of food, especially packaged and fried food from fast food chains as well as vegetable shortening and even some margarine.
They are formed when liquid oils such as vegetable oils are hydrogenated.
Like saturated fats, trans fatty acids also increase the bad cholesterol known as LDL cholesterol and reduce HDL or good cholesterol.
This may lead to an increase in the risk of heart disease.
Trans fatty acids are also linked to a greater risk of developing Type 2 Diabetes.
Check food labels to minimize the intake of saturated fats and trans fats.
Some labels do not list the amount of trans fats present, so to find out, just add the values for saturated, polyunsaturated and monounsaturated fats.
If the number is less than the “total fats” indicated on the label, the unaccounted is trans-fat.
The other method is to reduce consumption of fat.
Less total fat intake generally means less trans and saturated fats.
It transports fat-soluble vitamins A, D, E, and K through your body.
It contains the essential fatty acids (EFAs), which have a positive effect on the health of your heart and immune system.
It adds flavor and helps food taste good.
It is a concentrated source of energy.
It keeps us from feeling hungry since fats stay in the stomach longer than other foods and are digested more slowly. (25)
How Much Fat Do You Need?
Only 15-30% of the total body energy requirement should be provided by fats.
Excess fat in the daily diet can cause obesity, coronary heart disease and even increase the risk of certain cancers like colon and breast cancer.
At least 50% of fat intake should consist of vegetable oils rich in essential fatty acids.
How about Cholesterol?
What do you think of when you hear the word cholesterol?
Many people have a negative perception of cholesterol.
They have heard that cholesterol can be bad for them and that they must avoid it.
In fact, it is found in every cell of our body.
This soft and waxy substance is produced by the liver and intestine.
Cholesterol is essential for human life and plays many important roles in the body.
It is used to form vitamin D, with help from sunlight.
It is found in large amounts in the brain and spinal cord, insulating nerve tissues.
It is used in the manufacturing of adrenal and sex hormones, like oestrogen and testosterone.
It is converted to bile acid, the substance that helps digest fats.
It also helps to “waterproof” body cells.
The liver produces enough cholesterol to satisfy these functions.
Concerns associated with cholesterol start when food intake from meat, particularly from organs such as liver and kidney, eggs, dairy and other “animal” food sources, exceeds recommended levels.
Cholesterol is not present in plant foods like fruits, vegetables or vegetable oils.
It cannot just flow loose in our water-based bloodstream.
Instead, cholesterol is transported in the bloodstream in special protein packages called lipoproteins (i.e. fat and protein complexes).
There are many types of cholesterol, but the 2 major ones that we need to pay attention to would be LDL and HDL. (26)
What’s LDL cholesterol?
Also known as low-density lipoprotein, it is a major cholesterol carrier in our blood stream.
If there’s an excess amount of LDL circulating in our blood, it can slowly accumulate in the walls of our arteries.
It will combine with other substances and lead to the formation of plaque, which can clog up the arteries feeding the heart and brain.
This will inhibit flow of blood to our vital organs as the artery walls become less flexible and able to adjust to the flow of blood.
This condition is known as atherosclerosis.
The formation of a clot (thrombus) near the plaque can inhibit flow of blood to part of the heart and result in a heart attack.
Similarly, if the clot is found to be inhibiting blood flow to part of the brain, it can result in a stroke.
A high level of LDL cholesterol (160 mg/dL and above) reflects an increased risk of heart disease.
That’s the reason why LDL is considered “bad” cholesterol.
Therefore, you should keep it at a low level to reduce your risk of heart disease. (27)
What’s HDL cholesterol?
About 1/3 to 1/4 of blood cholesterol is carried by high-density lipoproteins or HDL.
Medical experts think HDL tends to transport cholesterol away from the arteries and back to the liver, either to be re-used, converted to bile acid, or disposed of in the bile.
Research has shown that HDL slows the growth of plaque by removing excess cholesterol from them.
HDL is known as “good” cholesterol since a high HDL level protects you from heart attack.
The opposite is also true: a low HDL level (less than 40 mg/dL) indicates a greater risk of health issues like stroke.
Avoid smoking since it is known to reduce HDL levels in our body.
Maintaining a healthy body weight through exercise helps to promote better HDL levels. (28)
Steps To Keep Your Cholesterol Under Control
Cholesterol can be obtained in 2 ways.
The first way is from our liver which produces about 1000 mg a day though the amount may vary at times.
Another 400 – 500 mg or more can come directly from food depending on the amount of saturated fats and cholesterol eaten.
Food that is high in cholesterol is not necessarily high in fat or saturated fat, and vice versa.
Vegetable oils, for example, are 100% fat but do not contain cholesterol.
Saturated fats are the chief culprit in raising blood cholesterol levels.
The following foods are high in saturated fats, cholesterol or both: bacon fat, beef fat, pork fat, ham fat, turkey fat, chicken fat, lard, butter, cocoa butter, cream, whole egg or egg yolk, hardened fat or oil, hydrogenated vegetable oil, shortening, full cream milk and cheese.
The food you eat can have an effect on your cholesterol level.
However, some people have inherited tendencies towards high blood cholesterol levels.
They may not be able to lower their blood cholesterol, even with a low-saturated-fat, low-cholesterol diet.
If this is found to be true, their doctor may consider adding a cholesterol-lowering medicine after trying a cholesterol lowering diet.
High blood cholesterol is a risk factor for heart and blood vessel disease.
Other risk factors include a family history of heart disease, being a male, high blood pressure, cigarette smoking, obesity and diabetes.
Some of these risk factors cannot be changed while some can.
The goal is to have as few risk factors as possible to lower your risk of heart disease.
Fats in the Diet: How Much Fats Is Too Much?
People with high blood cholesterol levels should reduce, but not eliminate, dietary fat.
Fats are necessary for good health, but health professionals have long observed that most diets contain too much fat, especially saturated fats.
If you are trying to reduce blood cholesterol or just want to stay healthy, you should limit your overall fat intake to 20 – 35 % or less of total calories by replacing foods high in fat or cholesterol.
If you have a condition where you are concerned about an increased risk of heart disease, diabetes or cancer, or you have difficulty maintaining your weight, you may want to reduce your fat intake towards the lower end of this range.
Eat a lot of fruits, vegetables, grains (breads, cereals, pasta, rice) and legumes (dried, cooked beans, peas and lentils), which eating small portions of lean meats, moderate portions of low-fat milk and milk products, and minimal quantities of all types of fats. (29)
Still, everyone should remember that by keeping their dietary intake of saturated fats low, they can significantly lower their dietary cholesterol intake.
A daily cholesterol intake of less than 300 mg is recommended by the American Heart Association.
Folks with heart disease should go lower than 200 mg/day.(30)
Recommended fat intake for optimal health
The type of fat consumed is important.
The following ratio of saturated / unsaturated fats is recommended:
Saturated fats: less than 10% of calories (mainly in animal products such as fatty meats, butter, whole-milk dairy products and egg yolk).
Polyunsaturated fats: not more than 10% of calories (Omega-3 in fish and seafood, and Omega-6 in vegetable oils such as corn, safflower and soy bean).
Monounsaturated fats: about 10% of calories (in olive oil, peanut oil, sunflower oil, avocados).
One of the reasons for these ratio recommendations is that saturated fats seem to stimulate the formation of LDL.
Unsaturated oils appear to be helpful because they decrease total cholesterol and LDL levels.
In addition, recent preliminary studies suggest that monounsaturated fats may actually have a favourable effect on serum cholesterol and ultimately, on coronary heart disease risk.
It lowers cholesterol and LDL without affecting the good HDL.
To help you determine your desired fat intake, have your cholesterol level checked (both total cholesterol and HDL/LDL ratio).
Also, consider other risk factors such as smoking, high blood pressure, diabetes, obesity and a family history of heart disease.
Then discuss diet changes and other preventive steps with your physician.
But whether you choose 30%, 20% or somewhere in between, remember to look at your diet as a whole, over a day’s period, and not just as individual food.
For example, if you eat an ice cream, cut back on the fat somewhere else in your diet to keep your total fat intake within the guidelines. (31)
The Result of Excess Fat Intake
The body can cope with a relative small intake of excess fat.
What constitutes an excess is a debate; however, you can be sure that more than 35% of your calories from fat is an excess.
To get an excess of fat in your diet, you would have to eat junk-food and/or animal source diet.
It is not properly balanced with plant-source food.
The association between excess fat and degenerative diseases, such as vascular disease and arthritis, is definitely established.
Others include obesity, heart disease and even cancers.
Thus, moderate intake of fat (about 15-30% of your caloric intake) will at least address this issue of excess.
Eggs are high in fat.
A single egg yolk contains 186 mg of cholesterol, which is close the maximum daily intake recommended (300 mg). (32)
But, egg whites are a good source of protein.
Thus, the best recommendation on eggs is to use them in moderation and where possible, use an egg white product as an egg substitute.
Fats should make up less than 30% of the total calories in your daily diet.
Based on a 2000 calories a day diet, this is about 70 grams of fat every day.
If you eat fewer than 2000 calories a day, you should eat fewer than 70 grams of fat.
Each gram of fat has 9 calories.
To find the total calories from fat – multiply the number of grams of fat in a serving shown on the label by 9.
1 ounce of potato chips has 10 g of fat
Amount of calories from fat = 90 (10 x 9)
If the potato chips have a total of 150 calories, fat contributes 60% of this total (90 divide by 150).
If more than 30% of the calories are from fat, that food is high in fat.
Although the percentages may be different, all the macronutrients are equally important.
Water – 6 to 8 glasses (230 ml) for adults
Which nutrient contains no vitamins, no calories, no protein, and no fat, is odourless, colourless, tasteless and yet, is essential to human life?
If you answered “air”, you are half right.
In the human diet, though, the answer is “water”, our fourth macronutrient.
In fact, water makes up about 60% to 70% of the body!
Humans can live for days or even weeks without food, but only a few days without water.
The food we eat and the beverages we drink give us the water our bodies need to function properly.
Why is water important?
It is the body’s most important nutrient, needed in the greatest amount.
Every cell in our body needs water to carry out a variety of essential functions.
Some of these functions include: transportation of nutrients and oxygen to cells and carrying away waste, lubricate joints and cushioning tissues and organs, and particularly in many normal chemical reactions.
Water is also used in the digestion and absorption of our food, and helps keep our stools soft to minimize constipation.
In addition, our body’s internal temperature regulation depends on water.
After we sweat, heat is loss during the evaporation process to keep us cool. (33)
We can be thankful for many complex processes inside our bodies that keep our water levels balanced.
Water does not have calories, so it rarely appears on charts that illustrate basic nutrient requirements.
But as adults, we must drink water daily in order to keep our body’s store of 45-55 litres of water replenished.
Our thirst mechanism usually signals us when we need water.
If we do not drink enough water, we can become dehydrated and our kidneys and other cells will not function properly.
Going without water can even be fatal, in as few as 2-3 days. (34)
Where Can Water Be Obtained?
We get water from fruits and vegetables , and some water from food such as bread and meat.
We also get water from juices, soft drinks and milk, but plain water is best for quenching thirst.
If possible, avoid coffee and tea when you feel thirsty – the caffeine causes the kidneys to eliminate, not conserve, body water.
Needed in small amounts, include:
Fat Soluble Vitamins
|Nutrient||Adult US RDA||Functions||Comments|
|Vitamin A (Retinol and Beta-carotene)||5,000 I.U.||Required for growth and bone development; helps maintain healthy skin abd mucous membranes which protect the body's organs; beta-carotene functions as an antioxidant||Large intakes (several times US RDA) may be toxic. During pregnancy, avoid greater than US RDA and seek advice of a physician. Beta-carotene is considered non-toxic.|
|Vitamin D||400 I.U.||Promotes normal bone and tooth formation; stimulates calcium absorption.||May be toxic with intakes greater than five times US RDA (2,000 I.U.).|
|Vitamin E||30 I.U.||As an antioxidant, protects body cells, vitamin A, and unsaturated fatty acids; maintains normal red blood cells.||Vitamin E needs increase as the intake of polyunsaturated fats increase.|
Water Soluble Vitamins
|Nutrient||Adult US RDA||Functions||Comments|
|Thiamine (B1)||1.5 mg||Assist in carbohydrate metabolism and energy production; required for normal nerve function.||No evidence of toxicity.|
|Riboflavin (B2)||1.7 mg||Assist in production of energy from foods and the formation of red blood cells; involved in many metabolic events.||No evidence of toxicity.|
|Niacin (B3)||20 mg||Assists in release of energy from carbohydrates, fats and proteins; helps maintain healthy skin.||One form of niacin; nicotinic acid, can cause flushing of the skin and gastrointestinal upset with very high intakes.|
|Pantothenic Acid (B5)||10 mg||Helps release energy from foods; needed for synthesis of many substances.||Considered non-toxic.|
|Pyridoxine (B6)||2 mg||Essential for protein metabolism and nervous system function; involved in synthesis of hormones and red blood cells.||Very large intake (gramme quantities) over a period of months can result in loss of motor coordination|
|Cyanocobalamin (B12)||6 mcg||Essential for normal growth and for production of red blood cells; helps maintain a healthy nervous system.||No evidence of toxicity.|
|Folic Acid (B9)||0.4 mg||Essential for red blood cell formation and synthesis of proteins in the body.||Adequate folic acid intake is particularly important during pregnancy. Considered non-toxic.|
|Biotin||0.3 mg||Involved in metabolism of carbohydrates and synthesis of fats and proteins.||No evidence of toxicity.|
|Vitamin C||60 mg||Essential for formation of connective tissue, bones, and teeth; assists in utilization of other nutrients; acts as an antioxidant.||Some may experience adverse effects with very large intakes.|
|Nutrient||Adult US RDA||Functions||Comments|
|Calcium||1 g (1000 mg)||Forms strong bones and teeth; stimulates blood clotting after injury; required for normal muscle and nerve activity.||Intakes of several grams per day can decrease absorption of iron, zinc or other minerals.|
|Phosphorus||1 g (1000 mg)||Form bones and teeth with calcium; regulates energy release from foods.||Phosphorus is abundant in the average diet.|
|Magnesium||400 mg||Required for normal muscle and nerve activity; involved in metabolism of energy and the genetic material, DNA.||No evidence of toxicity in healthy individuals. Large doses may cause laxative effect.|
|Iron||18 mg||Essential part of haemoglobin, which carries oxygen in the blood; involved in energy metabolism.||Considered non-toxic for healthy adults in amounts of up to 75 mg per day.|
|Zinc||15 mg||Essential for proper growth and development; involved in protein synthesis and digestion, wound healing, and synthesis of genetic material, DNA. ||Large chronic intakes (several times the US RDA) may impair copper status and immune response.|
|Iodine||150 mcg||As part of the thyroid hormone, helps regulate growth, development and energy metabolism.||Considered to be of low toxicity.|
|Copper||2 mg||Involved in iron metabolism and synthesis of proteins.||Considered to be of low toxicity.|
|Manganese||2.5 - 5.0 mg*||Necessary for the normal development of the skeletal and connective tissues; part of enzymes involved in fatty acid synthesis, involved in metabolism of carbohydrates.||Considered to be of low toxicity.|
|Selenium||0.05 - 0.20 mg*||As a component of an enzyme system, acts as an antioxidant.||Very large intakes (several times US RDA) can be toxic.|
|Chromium||0.05 - 0.20 mg*||Essential for normal metabolism of glucose.||Considered to be of low toxicity.|
|Molybdenum||0.15 - 0.50 mg*||Essential part of several enzymes in the body.||Evidence of toxicity is rare.|
|* RDA not established.|
1. Guthrie, Helen A., Introductory Nutrition, seventh edition, 1989.
2. Whitney, Eleanor Noss, and Hamiliton, Eva May Nunneley, Understanding Nutrition, third edition, 1984.
3. National Academy of Science, National Research Council, Recommended Dietary Allowances, tenth edition, 1989.
Latest RDA readings can be found here.
Vitamins, minerals, fiber, pigments, oils and flavor compounds are all phytonutrients.
Phytonutrients play a vital role in promoting human health.
Due to their special properties, phytonutrients have become the focus of research efforts around the world.
Plants manufacture phytonutrients to grow, reproduce and protect themselves from insects, bacteria, viruses and ultraviolet sunlight.
What is good for a plant also seems to be good for us.
Research shows that specific phytonutrients that help plants survive and ward off diseases offer the same benefits for humans.
Today, scientists have not only isolated and identified thousands of phytonutrients, but have also tied in the specific phytonutrients with the diseases they may help to prevent.
For example, indoles, phenolics and isothiocyanates such as sulforaphane, are found in vegetables such as broccoli.
Sulforaphane compounds may trigger the body’s defenses that suppress damage to our genetic material, or DNA.
Studies have also shown that flavonoids, specifically flavonoid quercetin, have inhibited the replication of human leukaemia cells in a test tube.
Other flavonoids found in soy have been shown to reduce serum cholesterol level. (37)
There are 2 classes of fiber: Soluble & Insoluble
Soluble fiber is sticky and meshes with water to form gel.
It includes pectins, guar, mucilages, and the fiber in oat bran, barley, dried beans, and other legumes.
Insoluble fiber absorbs large amounts of water, as much as 15 times their weight and hence creates soft bulky stools.
Wholewheat, wheat bran products, and the skin of fruits and vegetables are primary sources of insoluble fiber.
Why Is Fiber Important?
Fiber is known to play an important role in the following areas of health:-
Consistent adequate fiber intake has been shown to reduce the risk of cardiovascular disease and coronary heart disease through the lowering of LDL cholesterol levels in your body.
Testing has also shown that it could reduce bio-markers like blood pressure for heart disease.
Water-soluble fibers like guar gum, beta-glucan, psyllium are the most effective at lowering serum LDL cholesterol without affecting HDL levels.
Type II Diabetes and Glycemic Control
Large scale studies involving thousands of people have concluded that people who consumed more than 15 g of fiber on a daily basis had significantly lower risk of diabetes.
People who consumed more than 17 g of insoluble fiber a day or more than 8 g of cereal fiber a day had lower risk of type II diabetes.
Laxation and Regularity
Plays an important role in the natural laxation by increasing stool weight.
This will make the stool larger and softer to be easily released from your body.
It will reduce the risk of constipation.
Some fiber-rich foods provide greater satiation since they take a longer time to chew.
This will make you feel fuller and reduce your intake of food.
Some soluble fibers absorb water and make you feel bloated to reduce your food intake.
Since a higher fiber intake is associated with a higher consumption of fruits and vegetables, it plays an important role in promoting healthy weight in individuals.
Many reports in the 1970s have associated an increased risk in colorectal cancer due a lack of fiber in your diet.
However, there is no concrete evidence that this link exists.
Prebiotic Effect and SCFA Production
Some fermentable fibers like inulin, oligofructose and FOS are known as prebiotics.
They alter the composition of your intestine flora by promoting the growth of good bacteria.
Promotes the production of Short Chain Fatty Acids (SCFA) which helps to maintain your colonic health, regulates the absorption of sodium and water, enhances the absorption of calcium and other minerals.
Immune Function and Inflammation
The production of SCFAs also improves your immune function by increasing your resistance to illness and infection.
Soluble, non viscous fiber may help to alleviate the symptoms of inflammatory conditions like irritable bowel syndrome. (38)
How Much Fiber Do I Need?
The recommended fiber intake for both children and adults is 14 g/1000 kcal. (39)
Types of Fiber & Their Health Benefits
Your Next Steps
Start keeping track of your dieting habits.
Work towards having a balanced diet of 45-65% carbohydrates, 10-35% protein and 15-30% fats, 6-8 or more glasses of water, 14 g/1000 kcal of fiber, adequate minerals and vitamins intake and 5 – 9 servings of fruits and vegetables.
Use supplements to fill the gap in your diet if necessary.
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Published on 9 Sep 2016