The Essential Role of Vitamins in Nutrition
In order to truly understand the role of vitamins in nutrition; that is, how they work and what they do, we should look at the big nutrition picture or, more appropriately, jig saw. We need to understand certain terms like dietary supplements, essential nutrients, minerals, fatty acids, micronutrients and so on.
We eat food in order to obtain proteins, carbohydrates and fats which, when combined with other substances in the body, provide energy and the material which builds up tissues like muscle and helps children grow. These nutrients are called macronutrients – “macro” because you need a lot in the form of a meal to satisfy your nutritional needs.
When we look deeper into the nutritional process and discover how our bodies convert these macronutrients into energy, tissue growth and so on, we discover it is a complex chemical process.
Each of these macronutrients provides calories; the amount of calories varies as follows:
- Carbohydrates provide 4 calories per gram
- Protein provides 4 calories per gram
- Fat provides 9 calories per gram
Food products carry labels containing the amount and type of nutrients in the product. If, for instance, the label says the product contains 10 grams of carbohydrate, 2 grams of fat and 0 grams of protein per serving, then you would know that an average portion contains about 58 calories.
The only other substance that provides calories is alcohol – 7 calories per gram. Alcohol, however, is not considered a macronutrient because it is not needed for survival.
Enter the role of vitamins and minerals
These are only needed in tiny quantities, so they are called micronutrients, “micro” meaning small. To get a sense of the role of micronutrients with that of macronutrients, consider the relatively small amount of oil your car uses over a 3-month period compared with the large amount of gas you put in. You can fill the gas tank as many times as you want but the smooth running and well-being of the car depends on the oil in the engine. Just as your car needs oil, your body requires vitamins and minerals to keep you healthy and “running well”.
When we talk about small amounts of micronutrients like vitamins, we mean really small amounts. For example, the recommended intake of vitamin B9 (folic acid) for a pregnant woman is about half a milligram a day. A milligram is one thousandth (1/1000) of a gram. Compare this to your “macronutrient” hamburger which can weigh a modest 150 grams.
Micronutrients such as vitamins and minerals are vital to carrying out the necessary functions of the body – everything from producing hormones to helping the body derive energy from macronutrients like carbohydrates absorbed into the body.
Vitamins appear to act as enzymes – proteins that accelerate the rate of chemical reactions in the body. All processes in your body’s cells need enzymes and vitamins to speed up the process, often by millions of times faster than would occur without the enzymes and vitamins. Often different vitamins work in harmony with each other to carry out the various chemical functions of the cells.
Vitamins are also what is known as essential nutrients, meaning they are not food but are required for the body to function normally. Vitamins cannot be completely synthesized by the body and they must be obtained from dietary sources.
Fortunately, most of the foods we eat have vitamins, so if you are eating a well balanced diet you should be able to acquire the necessary vitamins. Often the source of a vitamin is what is known as a precursor to the vitamin, that is, a complex chemical which is easily converted to the vitamin in the body. An example would be beta-carotene which is found in broccoli, carrots and spinach. Beta-carotene is quickly converted to vitamin A within the body. When you buy a bottle of beta-carotene from your store, you are essentially buying vitamin A.
Vitamins are formed in plants which is how we get those vitamins, by eating the plant or the animal that ate the plant.
Water soluble and fat soluble vitamins
Vitamins are divided into two groups, those which are water soluble and those which are fat soluble. Water soluble vitamins, like the B family of vitamins and vitamin C, cannot be stored for long in the body; they need to be replenished every day. Because of this there is possibly more likelihood of vitamin B and C shortages in your body if you are not eating a balanced diet.
These water soluble vitamins are absorbed by the intestines and carried by the circulatory system to the specific tissues where they will be put into use. The B vitamins are believed to be greatly involved as co-enzymes in the chemical reactions that transfer energy from the basic food elements to the body.
The fat soluble vitamins are A, D, E and K can be stored within the body. The liver provides storage tissue for vitamins A and D, while vitamin E is stored in body fat and to a lesser extent in the reproductive organs. Relatively little vitamin K is stored. It must be mentioned that it is possible to have dangerous levels of vitamin A and D if you take an excessive amount of these vitamins.
We mentioned earlier that vitamins are essential nutrients, meaning they are vital for body functions and cannot be synthesized and have to be obtained from dietary sources. It is important to understand this and to make sure you and your family are either getting the right balanced diet or are taking vitamin supplements. These supplements are taken to compensate for a variety of factors, including:
a) an inadequate diet
b) too many processed foods
c) too much stress in your life
d) medications that can deplete vitamins levels
f) excessive alcohol consumption
g) you need extra for therapeutic reasons
Dosages and measurements of vitamins and minerals
You will see vitamins listed on labels in 4 types of measurements. The type of measurement used depends mostly on size of the amount needed. In crude terms you would not weigh a MAC truck on bathroom scales, you would use the truck weigh scales facility. Here are the three possible measurements you will see on packaging in order of heaviest weight:
Grams (g) – this is a small but significant weight amount of a vitamin – to give you an idea of this weight, an orange and a hamburger can be around 200 grams each.
Milligrams (mg)- this is one thousandth (1/1000) of a gram. One of the highest daily vitamin intakes would be vitamin C at only 90 mg per day i.e. 90/1000 of a gram
Micrograms (mcg)- this is one thousandth (1/1000) of a milligram (mg). An example of this measurement would be Folic Acid (Vitamin B9) for pregnancy at 600mcg per day or 600/1000 Milligrams (mg).
When looking at a supplement labels you should therefore see g for grams, mg for milligrams or the tiniest measurement mcg for micrograms. This is the metric measurements of weight.
While the average North American is accustomed to measuring things in the kitchen with cups, tablespoons and teaspoons, these measurements actually refer to the volume of the item being measured. The disadvantage here is that the measurement does not take into account whether the item is densely packed or coarsely chopped. By contrast these metric measurements ensure you know the consistent amount you are obtaining.
International Unit (IU). This is the tricky measurement because it is not a weight, it is a measurement of the potency of the vitamin. There is no fixed definition for IU, like there is for milligrams or micrograms. Generally speaking we cannot convert IU’s to mg or mcg’s, although the manufacturing experts do have a way of providing an equivalent weight for a specific vitamin to these IU units. The vitamins usually measured in IU’s are A,D and E.
Now you see a supplement label with the following ingredients, which you should be able to interpret and to your advantage, now compare with other products.
Example of a supplement label:
- Protein 22g
- Vitamin C 250 mg
- Vitamin B7 30 mcg
- Vitamin E 30IU
A common term you will come across is RDA which means Recommended Dietary Allowance, which was developed more than 60 years ago. This term is also known as the Recommended Daily Allowance. The RDA represents the establishment of a nutritional norm for planning and assessing dietary intake, and are the levels of intake of essential nutrients considered to be adequate to meet the needs of people.
These suggested intakes of vitamins or minerals are made for a specific individual profile of age, weight, sex, child, health status or pregnant etc.
In North America these recommendations are being unified for both Canada and the US and will be called the Dietary Reference Intake (DRI) and is a collaborative effort between the US and Canada.
In light of these new developments, there has been more amplification of the new DRI Dietary Reference Intake, as follows:
Estimated Average Requirements (EAR), expected to satisfy the needs of 50% of people in a particular age group.
Reference Daily Intake (RDI), the daily dietary intake level of a nutrient considered sufficient to meet the requirements of nearly all (97 – 98%) healthy individuals in each life – stage and gender group.
Adequate Intake (AI), where no RDI has been established, but the amount established is somewhat less firmly believed to be adequate for everyone in the demographic group.
Tolerable upper intake levels (UL), to caution against excessive intake of nutrients (like vitamin D) that can be harmful in large amounts.
By understanding measurements and labels you will be a better, more knowledgeable consumer of natural products.
Sailors used to be plagued by scurvy, a deadly disease in which collagen is not properly formed causing poor wound healing, bleeding of the gums, severe pain and eventually death. In the 18th century a Scottish surgeon, James Lind, carried out a clinical test that showed that citrus fruits helped prevent scurvy. He recommended the sailors eat lemons and limes during long sea voyages to avoid the disease. Eventually, this led to the name “Limey” as a nickname for sailors of the British Royal Navy.
In 1897, a Dutch physician, Christian Eijkman, discovered that eating unpolished rice instead of the polished variety helped to prevent beriberi, an acute disease characterized by great muscular disability with a painful rigidity of the limbs. The more natural rice had vitamin B1 which prevented the disease. The following year it was postulated that some foods had “accessory factors” that were necessary for the functions of the human body.
The good news is that in the developed world, thanks to an adequate supply of food and the addition of vitamins and minerals to common foods (often called fortification), diseases like these are rare.
One should be aware, however, that there is still a possibility of disease from deficiencies of vitamins D, B3 and A, which cause rickets, pellagra and night blindness respectively.
Even though extreme diseases such as these are not common, vitamins remain critical factors in contributing to our good health. Sustained depletion of vitamins to the body can, over time, contribute to a number of conditions such as heart disease, diabetes, cataracts, osteoporosis and even cancer.
The current trend towards nutritional counseling and nutritional medicine could, in time, prove as significant as the pharmaceutical era in curing and preventing disease.
Other essential nutrients
There are other essential nutrients such as minerals that cannot be synthesized by the body and have to be acquired from dietary intake or other sources. These will be explained in this book as they are often associated with vitamins within the same body functions.
Just like vitamins, minerals are required in very small quantities but the body’s requirements vary widely. For instance, the body of a 160-lb man may contain 2.3 grams of zinc but only 0.001 gram of cobalt.
Other essential nutrients, necessary for body functioning are:
- linolenic acid
- linoleic acid
Amino acid (for children only)
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