Nutrition Science

Nutrition is defined as the "science of food", the nutrients and other substances therein, their action, interaction and balance in relation to health and disease, and the processes by which the organism ingests, absorbs, transports, utilizes and excretes food substances[1].

The term nutrition refers to the science of how living organisms obtain and use food to support all the processes required for their existence while the study of nutrition incorporates a wide variety of scientific disciplines[2] such as biochemistry, agriculture, food industry, biology, genetics, physiology, informatics and many others sciences, reflecting a broad spectrum of academic and social disciplines.

Traditional nutrition science focused on the investigation of nutrient deficiencies and impairment of health. In the past few years, an emerging discipline of nutrition research, functional genomics, has provided new approaches and techniques to elucidate how nutrients modulate gene expression, protein synthesis, and metabolism[9].

Day to day, nutritional science is becoming a more complex science and new nutritional fields are emerging such as nutrigenics, nutrigenomics, metabolomics, proteomics and others omics sciences. For example, nutritional genomics, also called nutrigenomics, is an emerging field in the life sciences and is considered as one of the next frontiers in the postgenomic era. Nutrigenomics focuses on the relationship between dietary nutrients and gene expression using state-of-the-art technology[3]. Today it is well known that there are thousands genes that are expressing in response to diet. Genes expression can be activated by eating some food that contents specific nutrients. Genes expression in response to components from the diet can produce, prevent or cure some diseases. For example, diets deficient in choline and folate can facilitate carcinogenesis acording to epidemiologic and animal studies that have demonstrated increased ­carcinogenesis associated with diets containing low methyl donor nutrients such as methionine, choline and folate[4]; deficient diets in vitamin C produces scurvy because can't happen the hydroxylation of proline to hydroxyproline, an important amino acid in the synthesis of collagen[5]; some lipids, in add to be an important stores of energy, have function as fine modulators of cellular signaling and metabolism, especially poly-unsaturated fatty acids (PUFAs) of the Omega-3 and Omega-6 have been implicated in the modulation of various biochemical pathways[6]. Omega-3 and Omega-6 fatty acids in the diet are an example of opposite effects in the health. High omega-6/omega-3 ratio promotes the pathogenesis of many diseases, including cardiovascular disease, cancer, osteoporosis, and inflammatory and autoimmune diseases, whereas increased levels of omega-3 (a lower omega-6/omega-3 ratio), exert suppressive effects[7].

Actually, there are many scientists focused in understanding the human genome and the interactions between diet, gene expression, genetic variability, health, and disease because it is well know that the interaction of genetics and environment, nature, and nurture is the foundation for all health and disease and it has been shown that genetic factors determine susceptibility to disease and environmental factors determine which genetically susceptible individuals will be affected. It is not doubt that nutrition is an environmental factor of major importance[8] and nutrigenics, nutrigenomics and other similar fields are the future of a new and more effective nutritional science.

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[1] Joint Collection Development Policy: Human Nutrition and Food THE NATIONAL AGRICULTURAL LIBRARY THE NATIONAL LIBRARY OF MEDICINE THE LIBRARY OF CONGRESS February 27, 1998

[2] McGuire, Michelle and Beerman, Kathy A. 2011. Nutritional Sciences from Fundamentals to Food. Wadsworth Cengage Learning.

[3] Rimbatch, Gerald et al. 2005. Nutrigenomics, Taylor & Francis.

[4] Choi, Sang-Woon and Friso, Simonetta. 2009 Nutrients and Egigenetics. Taylor & Francis.

[5] Berdanier, Carolyn D. 1994. Adcance Nutrition Micronutrients. CRC Press.

[6] Chow, Ching Kaung. 2007. Fatty Acids in Food and their Health Impications. CRC Press.

[7] Smoupolos, A.P. 2001. Evolutionary aspects of diet, the omega-6/omega-3 ratio and genetic variation: nutritional implications for chronic diseases. Biomedicine & Pharmacotherapy 60 (2006) 502–507. ciencedirect.com.

[8] Simoupolos, Artemis P. 2008. The Importance of the Omega-6/Omega-3 Fatty Acid Ratio in Cardiovascular Disease and Other Chronic Diseases. Experimental Biology and Medicine. 233:674-688.

[9] Bagchi, Debasis. 2010. Genomics, Proteomics, and Metabolomics in Nutraceuticals and Functional Foods. Willey-Blackwell.

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Diet and Nutrition

‘You are what you eat’
Chinese proverb

Diet and nutrition are not the same. Diet is the sum of food that people eat each day while nutrition is the science of how living organisms obtain and use food to support all the processes required for life. Depending of the food that we are eating, they can have a positive or a negative impact in our health because nutrition is directly related to health. For example, if we have a diet with foods with high calories that have low nutrient density such as potato chips, cakes, soda, candies and food with excessive of saturated fats we will become obese and we will have high risk of getting cardiovascular diseases, diabetes, arteriosclerosis and other diseases associated with obesity and food with bad quality, instead if we are eating vegetables and fruits, less red meat and more fish we will enjoy a better and a healthy lifestyle. The function of the diet is provide nutrients to our body throughout the foods we are eating. Nutrients can directly influence genetic expression, determining the type of RNA formed and also the proteins synthesized, also they act as substrates and cofactors in all of the metabolic reactions in cells necessary for the growth and maintenance of structure and function[2].

The foods we are eating must provide all the essential macronutrients, those that our body is not able to build such as certain fatty acids and amino acids, and all the necessary micronutrients, vitamins and minerals. Also it is important that we include in our diet functional foods that have bioactive phytochemicals that benefit our health. Phytonutrients apparently act collectively and synergistically, each phytonutrient being thus a part of an orchestra[3]. Indeed some of the conventional micronutrients are also often part of such an orchestra, as will be evident from the fact that some micronutrients like carotene, ascorbic acid, tocopherols and selenium also act as antioxidants in conjunction with carotenoids, flavonoids and phenolic compounds. It is the sum of the individual contributions of each phytonutrient, many of them perhaps quite modest individually, that exerts the impact on disease prevention[3].

The quantity and the quality of food that we are eating in our diet are directly influencing our health. A balanced diet means an equilibrated and optimum nutrition always have a positive impact on our health. Nutritional health is maintained by a state of equilibrium in which nutrient intake is balanced by nutritional requirements[2]. Malnutrition occurs when net nutrient intake is less than requirements (undernutrition) or exceeds requirements (overnutrition). Both under- and overnutrition lead to metabolic changes which have acute and chronic consequences for health[2]. Over nutrition doesn’ t mean that people are always overnurished with both macronutrients and micronutrients. In the world there are a lot of people that have a deficient nutrition; for example those people that are eating food whit 'empty calories' such as food with a lot of sugar, saturated fats, starchy food, fast food that are rich in calories but poor in micronutrients, so they are macronutrients overnurished but they are micronutrients undernurished. According to observations and experiments performed, many other mammals, including Old and New World monkeys, dogs, cats, and rats become overweight and insulin resistant when they are fed a western diet. Free-ranging mammals in their natural habitat are apparently not affected by advanced coronary atherosclerosis, and atherosclerosis promotion and regression in animal experiments is highly dependent on dietary manipulation[1].

A good diet should satisfy all daily nutritional requirement to support all physiological processes. Food must provide nutrients that give to our body energy, molecules useful for building and repairing body tissue and regulating body processes, but also it is important to think in functional foods as a part of our diet because the phytochemicals compounds can be beneficial to our health[4]. The greater the range of foods, the less likely are there to be ‘gaps’ in the nutrient intake, and the more likely it is that the consumer will meet the nutritional needs[4].

There is evidences that diets based largely on plant foods ─vegetables and fruits─ and specially some kind of fish can help to prevent and reduce the incidence of chronic diseases, also it is known that they are associated with health and longevity when they are eating in adequate quantity.

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[1] Hublin Jean-Jacques and Richards, Michael P. 2009. The evolution of hominin diet. Springer.
[2] Gibney, Michel J. et al. 2009. Introduction to human nutrition. Wiley-Blackwell.
[3] Simopoulos, A.P. and Gopalan, C. 2003. Plans in Human Health and Nutrition Policy. Vol. 91. Karger.
[4] Barasi, Mary E. 2003. Human nutrition. A health perspective. Oxford University Press Inc.

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Some Curiosities and a Short History
of the Nutrition Science

Although nutrition research commenced more than 200 years ago in the dawn of the chemical revolution[3], about more two thousand years ago there are evidences that human being began to think how the nutrition, the environment and physical exercises influence on the health and the life. For example Hippocrates said in his writings in the Regime in Health: So in fixing regimen pay attention to age, season, habit, land, and physique, and counteract the prevailing heat or cold. For in this way will the best health be enjoyed. Walking should be rapid in winter and slow in summer, unless it be under a burning heat. Fleshy people faster, should work thin slower… Fat people who wish to become thin should always fast when they undertake exertion, and take their food while are and before they panting and before they have cooled, drinking beforehand diluted wine that is not cold. Their meats should be seasoned with sesame, sweet spices, and things of that sort. Let them also be rich. For so the will be appetite satisfied with a minimum[2]. For Hippocrates health comes from the balance between foods and exercises; it must know in detail the qualities of each and of others, but also the influence of other factors, human or external: age, sex, location, the winds, seasons etc. Finally and above all, the author has discovered-green personally the prodiagnose, preventive diagnosis which announces next imbalances between foods and exercises, and the regime which, in each case, maintain or recover balance and, therefore, health [1].

In the middle of 1700s many of the chemists involved in the “Chemical revolution” in France, including its most famous member Antoine Lavoisier, also had an interest in metabolism. In collaboration with his assistant Armand Seguin, he measured human respiratory output of carbonic acid (that we now know as carbon dioxide), both at rest and when lifting weights, and showed how it increased with activity [5].

 

In the early of 1800s there is registered in the history of the nutrition some experiments looking for the effects of particular specific food on the health. Magendie, a French physiologist, considered a pioneer of experimental physiology, performed some nutritional experiments using animals; he said I put a dog, about three years old, fat and healthy, upon a diet exclusively of pure refined sugar, with distilled water for drink; he had them both without any limit. For seven or eight days, he appeared to be very well; he was sprightly, ate with avidity, and drank as usual. He began to grow thin the second week, although his appetite was good, and he ate six or eight ounces of sugar in twenty-four hours. His alvine excretions were neither frequent nor copious, and the urine was in sufficient abundance. The emaciation increased in the third week, the strength diminished, the animal lost spirit, and its appetite became less. At this period, there occurred, first upon one eye and then upon the other, a small ulcer on the centre of the transparent cornea; it augmented rapidly, an at the end of a few days it was about a line in diameter, its depth increasing in the same ratio; the cornea become soon perforated, and the humours of the eye discharged [4]. It is no doubt that this is an interesting example that clearly illustrate the visible effect on the health of a single type of food such as refined sugar.

The “golden age of nutrition” began in the early 1910s and continued into the 1940s when nutritional sciences focused primarily on diseases associated with single nutrient deficiencies[3]. The firsts researches in this way stated to find a cure to the scurvy disease. Findings and solutions were based mainly on observations that can be illustrated with the following examples:

The Doctor was of opinion that Scurvy only followed the use of salted provisions, or even animal food without fresh vegetables. There are many cases on record where the disease followed other kinds of diet. It is a very common complaint in the country ships in the East Indies, where the religion of the natives obliges them to live at sea on rice; but they are always recovered by fresh fruits when they return to port… This disorder is most frequently met with at sea: few ships in any climate, after being eight ot ten weeks from port, escape the Scurvy, if the crew are obliged to live on the common allowance of salt provisions, with no fresh vegetables… A quantity of sugar ought, therefore, to be always mixed with the spirits and water; orange, lime, or lemon juice where they can be produced, which make an artificial wine, may be added, as rendering the composition still more salutary and antisorbutid [6].

It is the pioneering controlled clinical trial of the various therapies recommended for the disease of scurvy, which was carried out in 1746 by James Lind on sailors at sea. Lind was, at that time, a 30-y-old ship’s surgeon in the British navy, with no academic education, but with a special interest in the problem of scurvy [5]. About his findings, Dr James Lind wrote, there is no other particular virtue in which they all agree; a greater diversity of qualities being found in vegetable than in animal substances. But, besides what has been mentioned, vegetables have great and peculiar virtues in this disease, arising from a combination of various qualities; of which all vegetables possess one or more, in a greater or less degree; and do from thence accordingly become more or less antiscorbutic [7].

Beriberi is another example of disease related with nutritional issues. In the early of 1800s in Tokyo it was described a disease called kakké, similar to the beri-beri disease, that produced slight swelling and paralysis. Concerned by the disease, Japanese people began to look for a cure with Western doctors. Referent to kakké, an early Chinese writer, Han Yu (a.d. 768–824), had commented that, while the wheat-eating people in northern China were free of the disease, those living near rivers in the south and eating rice were subject to it[9]. In the latter 1800s after observations on diet compositions of the creews, the conclusions offered by Haynes, and which his facts seem amply to warrant, are expresed as follows: Hoting has been reported from subsequent voyages to alter the opinion: (a) That beri-beri is confined to a very great extent to rice eating races, and with proper care will not develop in less than seven months. (b) That the substitution of a mixed diet of weat-flour, beans, potatoes, etc, to the exclusion of rice, mitigates, if it does not entirely prevent, the disease… Moreover, among the rice-eaters already affected, the disease disappeared when the rice was replaced by other articles or fresh supplies[8].

To understand nutrition meant to understand what the body did to the food (as nutriment) in order to assimilate it into its tissues[4]. During the 19th century, chemists and physiologists began to study the composition of foods and the nutritional requirements of humans and animals. By the late 19th century, the prevailing dogma held that there were four essential elements of nutrition: proteins, carbohydrates, fats, and minerals[10].

In 1906, Frederick Gowland Hopkins (1861 – 1947) articulated what is now known as the “vitamin theory” during a speech given in London[10]. In 1922 Hopkins referring to the vitamins as a new component in food wrote: I will pass at once to a newer aspect of our knowledge concerning the nutritional demands of the body,… when we are seeking to define an efficient dietary, of considering the nature of the material, as well as the energy supply… I mean, of course, the facts concerning the accessory food substances, as I once ventured to name them vitamines… By this time I had come to the conclusion that there must be something in normal foods which was not represented in synthetic diet made up of pure protein, pure carbohydrate, fats and slats; and something the nature of which was unknown. Yet at first it seemed so unlikely! So much careful scientific work upon nutrition had been carried on for have been missed?[11] After Hopkins performed experiments feeding rats with synthetic milk with fat, protein, carbohydra and mineral salts and saw that experimental animals only grow normally adding a minute quantity of fresh milk. He called “accessory food factors” the compounds present in the fresh food that returned the normal grow in the experimental animals. Casimir Funk (1884 – 1967) proposed the term “vitamine” instead of “accessory food factors” in 1912 for the deficient substances in the food as related to beriberi, scurvy, and pellagra. Soon these unknown factors in foods became synonymous with both “vitamine” and “accessory food factors”[10]. Some, such as Professor Gies, are of opinion that they supply the body with certain necessary chemical units which the body is unable to manufacture. Others –Professor Hopkins, for example,– regard these vitamines in the light of stimulators, in that they exert a stimulating influence upon the various activities of the body.[12] One of the finding is that the vitamines have this in common, that they are all necessary to complete a synthetic diet[13].

In the 20th century began researches focused on deficient substances that produce nutritional diseases called vitamines. Early researches focuses on scurvy, beriberi, rickets and pellagra diseases. Rats, mice, guinea pigs, rabbits, cats, and dogs were the main animals used for the purpose of experimental vitamins research. The study of the nature of the vitamins focused on several steps: 1. Fractionation of the active material according to the known methods. 2. Attempts to separate the active material by solubility and selective adsorption. 3. Testing of vitamine-like action of combinations of known or unknown composition. 4. Synthetic experiments with substances obtained in vitamine work[13]. All vitamins were discovered during this century.

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[1] [1] Joly, Robert. 2003. Hippocratis De Diaeta – Hippocrate Du Regime (Corpus Medicorum Graecorun I 2,4). Akademie Verlag.

[2] Hippocrates Vol. IV Heracleitus on the universe. Regime in Health. Harvard University Press. MCMLIX.

[3] Rimbatch, Gerald et al. 2005. Nutrigenomics, Taylor & Francis.

[4] Magendie, F. 1824. Summary of Physiology. Published by Edward J. Coale. Baltomore.

[5] Carpenter, Kenneth J. A. 2003. Short History of Nutritional Science: Part 1 (1785–1885). American Society for Nutritional Sciences. J. Nutr. 133: 638 – 645

[6] Trotter, Thomas. Observation on the Scurvy; with a review of the opinions lately advanced on that disease and a new theory defended, on the approved method of cure, and the induction of pneumatic chemistry. Longman, Paternoster Row and J. Watts, Gosport. M.DCC.XCII

[7] Lind, James. Treatise in the Scurvy. S. Crowder, D. Wilson and G. Nicholls, T. Cadell, T. Becket and Co. G. Peach, and W. Woodfall. MDCCCLXXLI

[8] Braddon, W. Leonard.1907. The cause and prevention of beri-beri. Rebman.

[9] Carpenter, Kenneth J. A. 2000. Beriberi, white rice, and vitamin B. A Disease, a Cause, and a Cure. University of California Press.

[10] Semba, Richard D. 2012. The discovery of the vitamins. Int. J. Vitam. Nutr. Res. 82(5), 310-315.

[11] Hopkins, P. Gowland. 1922. Newer aspects of the nutrition problem. Columbia University Press.

[12] Harrow, Benjamin. 1921. Vitamines. Essential food factors. E.P. Dutton & Company.

[13] Funk, Casimir. 1922. The vitamins. Williams & Wilkins Company..

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