Q. It seems that not so long ago the only people interested in nutrition were A- level biology and home economics teachers and may be mum. Now the topic is constantly in papers and magazines. Why is nutrition such a popular topic these days? And what do vitamins and minerals have to do with it?
A. Critics say that our current fascination with nutrition is merely a media craze dreamed up by vitamin supplement industry to strike a chord with the middle aged. Nut that now where the truth. Nutrition is a major topic just now for good reason. Within the last 10 years or so, researchers on the both sides of the Atlantic have been conducting impressive new nutrition studies. This research goes miles beyond our previous understanding of the role nutrition plays in health.
Q. Who is doing such research?
A. Well, The British Ministry of Agriculture, Fisheries and Food, for a start, prestigious research centers such the British Medical Research Council, and the Rowatt Institute in Aberdeen, the American National cancer Institute, the Us department of Agriculture Human Nutrition Research, and dozens of well known teaching university department such as Department of Community, Medicine at Cambridge University. This kind of research has attracted the attention of scientist all round the world. It is currently going in France, Germany, Spain, Italy, Denmark, Sweden, The Netherlands and Greece.
Q. What all this research looking at?
A. researchers have been exploring many different aspects of nutrition the benefits and hazards of different kinds of fats, such as saturated fats, fish oils and hydrogenated fats (the hardened vegetable oil found in magazine for example, the role of different types of fibers in reducing and cholesterol and cutting the risk of colon and breast cancers and the reason behind the fact the people who eat large quantities of fruits and vegetables seem to have reduced risk of many kinds of diseases.
Q. All right but what does vitamins and minerals have to do with it?
A. As researchers isolate food components that seem to protect against say, heart disease and cancer they are discovering that vitamins and minerals plays an important role in providing that protection a role beyond what was previously thought. Vitamins and minerals are certainly not only the components of food that offer health benefits but they are proving to be significant.
Q. What kind of benefits you are talking about?
A. Scientist who thought that the major benefits of nutrition were to prevent deficiency related diseases such as rickets, beriberi, and scurvy. Are learning that vitamins and minerals play for more fundamental and long term roles in the body than anybody had previously suspected.
Specifically, they are gathering evidence that vitamins and minerals influence the health of nearly every organ and may slow or even reverse many diseases previously thought an inevitable part of ageing, impaired immunity, nerve degeneration and other chronic health problems.
Q. Can you give some examples of this evidence you are talking about?
A. Throughout this book, as we discuss specific, nutrition’s we will present such evidence. For now there are some broad examples. High intake of vitamin C and E and beta carotene (the orange pigment found in carrots and other vegetables and fruits) are linked with reduced deaths from cancer and heart disease. High intakes of potassium, magnesium, and calcium are all associated with lower blood pressure. High intake of folic acid decreases a woman’s chances of having a baby with serious birth defects and also birth reduces her risk of developing cervical abnormalities which can lead to cancer.
Q. what do you mean by high intake?
A. In general, high intake means intake that is above average relative to the general population. If most of the people in a group are getting about 70 milligrams of vitamin c a day, for instance people getting more than that amount would be considered a high intake group. In case you stop reading at this point, please note that really high intake of certain vitamins especially vitamins A and D can be seriously dangerous.
Q. And what about low intake?
A. In general, it means below average intake of a particular nutrient relative to a general population. You see in general population studies scientist usually divide people they are studying into low, medium and high and very high nutrient intake groups. The high and very high intake groups for differences in disease risk. From such studies, scientists come up with amounts of nutrients which seem to offer protective benefits.
Q. Can you tell me more about this research?
A. Research has been worldwide and has included hundreds of population studies which examines and compare eating habits and patterns of illness among large numbers of people. These studies are designed to reveal association between certain eating habits nutrients intakes and diseases risks. For instance, dozens of studies now show that people who eat a lot of fruits and vegetables suffer fewer of certain types of cancer than people whose intake of fruits and vegetable is low.
Q. how many helpings a day of fruits and vegetables do studies consider a lot?
A. In most of these studies four or more helpings a day of fruits or vegetables qualifies as a lot.
Q. How many helpings a day of fruits and vegetables is considered as low intake?
A. One or no helpings a day is considered low intake.
Q. What is a helping?
A. This may vary from study to study, but, in general, a helping in one medium sized fruit or vegetable juice, half a cup of cooked or raw vegetable or fruit, cup of raw leafy vegetable or a quarter cupful of dried fruit.
Q. How do researchers test such findings?
A. In addition to years of animal research, researchers have recently moved into what are called clinical intervention trials. Some of these studies add nutrients to the diets pf people at a risk of certain disorder to see if it helps prevent development of the disorder. Others add a nutrient to the diets of generally healthy people to see if it improves certain aspects of the health such as immune function.
Q. Are there any noteworthy results yet from these human clinical intervention trials?
A. Researchers at several cancer centers have found that the some synthetic vitamin A like substance used to treat severe acne, isotretinoin helps to prevent recurrence of leukoplakia a precancerous condition of the mouth that often afflicts smokers.
And we touched upon earlier researchers now know that supplemental folic acid, B vitamin, reduces women’s risk of having a baby with spinal before. These are serious birth defects that result in spinal cord and brain abnormalities.
Q Anything else?
A. Researchers have found that vitamin B6 supplements can boost immunity in older people, who apparently may need more than currently recommended amounts of this nutrient to maintain adequate body stores.
Many other studies now ongoing should results in several years time. One particular study is testing whether high doses of supplemental beta carotene help prevent lung cancer in smokers who have been exposed to asbestos.
Another by researchers in US and China is locking to see if supplementing people’s diet with selenium a trace mineral reduces the high rates of cancer in people living in certain areas of China where soil leaves of selenium are low. Researchers are investigating whether giving people at risk of colon cancer up to 50 grams a day of calcium reduces their risk of developing potentially premalignant intestinal polyps
Q. What happens once the results of these studies are known?
A. The results can help guide researchers in further studies and provide information that helps people to make decisions regarding diet and supplementation. But more such studies are probably needed to clarify the roles of vitamins and minerals in disease prevention. It is now generally recognized that, over the years good eating habits protect people from range of diseases, including cancer. What is not known whether short term treatment with dietary supplements can undergo the harm of years of self indulgence in the wrong kinds of food.
Vitamins
Q. All this sounds very interesting but in am afraid we will have to go back to basics. I know very little about nutrition and even less about vitamins and minerals. So lets’ start at the beginning what exactly are vitamins?
A. Vitamins are nutrients food components obtained from our diet which have been found to be essential in small quantities for human life. This means that one /itamin is missing from your diet, your body does not function normally.
Vitamins are group of chemically unrelated orange substances. Organic substances are compounds containing the chemical element carbon and they come only from living materials plants or animals or from substances that were one living materials such as petroleum oil or coal.
Q. What do vitamins do?
A. Vitamins perform countless different functions in the body and individual vitamins have special functions. As a group, however most of them share certain functions such as the promotion of growth the promotion of the ability to produce healthy off spring and the maintenance of health. They must be present for the body to be able to utilize other essential nutrients such as minerals fatty acids, and energy sources (for example, carbohydrates and sugar) vitamins are also important to a normal appetite and digestive tract to mental alertness , to the health issues and to resistance to bacterial infections.
Q. How do vitamins do all these things?
A. Our bodies use many of the vitamins, including the whole of the B group, to make substance called coenzymes. Coenzymes are vital participants in many of the ongoing chemical reactions in our bodies which in fact, are the very essence of life. This chemical reaction provides our bodies cells with energy from food a process called metabolism. These chemicals reactions allow cells to grow and divide, promoting growth in children and tissue repair in adults. They also allow our bodies quickly to build up a supply infection fighting immune cells when necessary.
If you lack even one vitamin, you may fall to thrive as a child or be similar than normal and may fail to develop sexually. As an adult, if you lack a vitamin you eventually develop a deficiency related diseases. Such as scurvy from lack of vitamin C, and rickets from lack of vitamin D and if your are more vulnerable to infection. Exactly which health problem you develop depends upon which vitamin you are lacking.
Q. I know from reading the labels from my cat’s food tins that cats need vitamin too. But do animals need the same vitamins that humans need?
A. All animals need some vitamins, but not every vitamin which has been discovered to be essential for humans is also needed by animals. There are however, more similarities that differences. Hence one’s interesting difference unlike humans most animals can make vitamin C in their bodies so they do not need to get this vitamin from food. Guinea pigs are the exception, which why they were used as animals models for studies in which humans could not be used (for providing the ability of vitamin C to prevent scurvy.)
Humans however, can make vitamin D in their bodies. And some of the vitamin needs of animals and humans from microorganisms living in the digestive tract.
Q. What? We have things living in our bodies that make vitamins for us?
A. Yes. But while the fact may be startling its not as bad as you think. Indeed, this is a healthy state of affairs. All humans have bacteria, also called microflora, or microorganisms, living in their intestines and these bacteria synthesizes or produce certain amounts of vitamin K, B and biotin, which are absorbed through their intestines. In most cases, however we also rely on food sources of these vitamins to stay healthy.
Q. How many vitamins are there?
A. There are 13 vitamins. Four are fat soluble A, D, E and K and nine are water soluble the B vitamins and vitamin C. the B vitamins are essential for human health are B1, or thiamine B2 or riboflavin, niacin, B6, B12 or cobalamin, folic acid and pantothenic acid and biotin.
Q. Why the distinction between fat and water soluble vitamins? Is it important only to researchers?
A. Its important to researchers because it helps them to identify the functions of these vitamins. As for the rest of us we should know that fat soluble vitamins occur in fats and oils so we need a bit of fat, in the diet to get them. Also if for some reason we are taking supplements of these vitamins it is best to take them with a meal that contains some fat so that there will be a supply of bile to help in their absorption. We should also know that fat soluble vitamins tend to stay in the body longer than most water soluble vitamins so some of the fat soluble vitamins can build up to unhealthy levels more easily than most water soluble vitamins can. These toxic levels are likely to be reached only by taking supplements or by eating foods exceptionally rich in a particular nutrient.
Q. Are those all the vitamins there are?
A. There are other substances which are occasionally considered to be essential vitamins. their vitamin status however has not been established. These substances include choline, inositol, bioflavonoids, para- aminobenzoic acid and a few others.
Q. What does that mean/ their vitamin status has not been established?
A. these are nutrients which may be vitamins for certain species, which human requires under certain conditions not yet understood or which have functions not yet understood. We talk more about these so called quasi vitamins a little later.
Q. Beta carotene is getting lot of public attention these days, yet you didn’t list it as one of the 13 known vitamins. is it one of the quasi vitamins?
A. No. beta carotene is precursor to vitamin A. in other words it’s a substance from which vitamin A can be made. We discuss its role more detail in the section on vitamin A in chapter 8
Q. You said that vitamins are involved in energy metabolism. Do they provide energy?
A. Vitamins don’t provide energy but some are fundamental participants in the energy producing reactions of our bodies the reactions which help our cells to burn sugar or fat to make energy. Vitamins themselves however, are significant sources of biological energy. For practical purposes they don’t provide calories.
Q. How do we get vitamins?
A. Part of a definition of the vitamin is that it must be obtained at least in part, from outside the body, since we cannot make vitamins in out bodies in adequate amounts. We obtain vitamins from the foods we eat including vitamin enriched foods and from vitamin supplements.
Q. Do all foods contain vitamins?
A. Just about every food we eat contains at least some vitamins, but some are much better sources than others.
Some foods are considered as traditional health foods, liver blackstrap, molasses, brown rice, wheat, eggs, brewer’s yeast and seaweed, for instance contain an impressive array of vitamins and minerals.
Other food provides large amounts of one part’s cular vitamin. Citrus fruits broccoli, and red pepper are loaded with vitamin C, for example, wheat germ oil is a good source of vitamin E and parsley is packed with vitamin K.
Q. Are there any foods that don’t contain vitamins?
A. Although they provide more than enough calories certain foods, such as sugar, animal fat and alcohol are devoid of vitamins. They are what nutritionists and dieticians call empty calories. In fact, they have worse than that since these food require vitamins and minerals to be metabolized. So they use up important nutrients in our bodies without replacing them. Eating a lot of sugar or animal fat or having more than having a drink or two alcohols a day increases your vitamin needs, which puts you at increases risk of developing vitamin deficiencies.
