Nutrition
The “Nutrition Facts” table indicates the amounts of nutrients which experts recommend you limit or consume in adequate amounts.Nutrition (also called nourishment or aliment) is the provision, to cells and organisms, of the materials necessary (in the form of food) to support life. Many common health problems can be prevented or alleviated with good nutrition. The diet of an organism refers to what it eats. Dietitians are health professionals who specialize in human nutrition, meal planning, economics, preparation, and so on. They are trained to provide safe, evidence-based dietary advice and management to individuals (in health and disease), as well as to institutions.Poor diet can have an injurious impact on health, causing deficiency diseases such as scurvy, beriberi, and kwashiorkor; health-threatening conditions like obesity and metabolic syndrome, and such common chronic systemic diseases as cardiovascular disease, diabetes, and osteoporosis.
Overview
Nutritional science investigates the metabolic and physiological responses of the body to diet. With advances in the fields of molecular biology, biochemistry, and genetics, the study of nutrition is increasingly concerned with metabolism and metabolic pathways, the sequences of biochemical steps through which the many substances of living things change from one form to another.
The human body contains chemical compounds, such as water, carbohydrates (sugar, starch, and fiber), amino acids (in proteins), fatty acids (in lipids), and nucleic acids (DNA/RNA). These compounds, in turn, consist of elements such as carbon, hydrogen, oxygen, nitrogen, phosphorus, calcium, iron, zinc, magnesium, manganese, and so on. All of these chemical compounds and elements occur in various forms and combinations (e.g. hormones/vitamins, phospholipids, hydroxyapatite), both in the human body and in organisms (e.g. plants, animals) that humans eat. The human body consists of elements and compounds ingested, digested, absorbed, and circulated through the bloodstream. Except in the unborn fetus, it is the digestive system which carries out the first steps in feeding the cells of the body. In a typical adult, about seven liters of digestive juices enter the lumen of the digestive tract. They break chemical bonds in ingested molecules and modulate their conformations and energy states. Though some molecules are absorbed into the bloodstream unchanged, digestive processes release them from the matrix of foods in which they occur. Unabsorbed matter is secreted in the feces.
Studies of nutritional status must take into account the state of the body before and after experiments, as well as the chemical composition of the diet and the products of excretion. Comparing the food to the waste can help determine the specific compounds and elements absorbed in the body. Their effects may only be discernible after an extended period of time, during which all food and waste must be analyzed. The number of variables involved in such experiments is high, making nutritional studies time-consuming and expensive, which explains why the science of human nutrition is still slowly evolving.
In general, eating a wide variety of fresh, whole (unprocessed), foods has proven favorable compared to monotonous diets based on processed foods. In particular, the consumption of whole plant foods slows digestion and provides higher amounts, and a more favorable balance, of essential nutrients per Calorie, resulting in better management of cell growth, maintenance, and mitosis (cell division), as well as better regulation of appetite and blood sugar. Regularly scheduled meals (every few hours) have also proven more wholesome than infrequent, haphazard ones.
Nutrients
There are seven major classes of nutrients: carbohydrates , fats , fiber , minerals, DNA, vitamins, and water. These nutrient classes can be generally grouped into the categories of macronutrients (needed in relatively large amounts), and micronutrients (needed in smaller quantities). The macronutrients are carbohydrates, fats, fiber, proteins and water. The micronutrients are minerals and vitamins.
The macronutrients (excluding fiber and water) provide energy, which is measured in Joules or kilocalories (often called “Calories” and written with a capital C to distinguish from gram calories). Carbohydrates and proteins provide 17 kJ (4 kcal) of energy per gram, while fats provide 37 kJ (9 kcal) per gram.[1] Vitamins, minerals, fiber, and water do not provide energy, but are necessary for other reasons.
Molecules of carbohydrates and fats consist of carbon, hydrogen, and oxygen atoms. Carbohydrates may be simple monomers (glucose, fructose, galactose), or large polymers polysaccharides (starch). Fats are triglycerides, made of various fatty acid monomers bound to glycerol. Some fatty acids are essential, but not all. Protein molecules contain nitrogen atoms in addition to the elements of carbohydrates and fats. The nitrogen-containing monomers of protein, called amino acids, fulfill many roles other than energy metabolism, and when they are used as fuel, getting rid of the nitrogen places a burden on the kidneys. Similar to fatty acids, certain amino acids are essential.
Other micronutrients not categorized above include antioxidants and phytochemicals.
Most foods contain a mix of some or all of the nutrient classes. Some nutrients are required on a regular basis, while others are needed less frequently. Poor health can be caused by an imbalance of nutrients, whether an excess or a deficiency.
Carbohydrates
A pack of toasted bread is a cheap, high calorie nutrient (usually unbalanced, i.e., deficient in essential minerals and vitamins, because of removal of grain bran) food source with a long shelf-life.
Carbohydrates may be classified as monosaccharides, disaccharides, or polysaccharides by the number of monomer (sugar) units they contain. They are found in large proportion in foods such as rice, noodles, bread and other grain-based products. Monosaccharides contain 1 sugar unit, disaccharides contain 2, and polysaccharides contain 3 or more. Polysaccharides are often referred to as complex carbohydrates because they are long chains of sugar units, whereas monosaccharides and disaccharides are simpler. The difference is important because complex carbohydrates take longer to digest and absorb since their sugar units are processed one-by-one off the ends of the chains; the spike in blood sugar levels caused by substantial amounts of simple sugars is thought to be at least part of the cause of increased heart and vascular disease associated with high simple sugar consumption. Simple carbohydrates are absorbed quickly and thus raise blood sugar levels more rapidly.
Fat
37 J/g (9 cal/g)
Fats are composed of fatty acids (long carbon/hydrogen chains) bonded to a glycerol; they are typically found as triglycerides (three fatty acids attached to one glycerol backbone). Fats may be classified as saturated or unsaturated. Saturated fats have all of their carbon atoms bonded to hydrogen atoms, whereas unsaturated fats have some of their carbon atoms double-bonded in place of a hydrogen atom. Unsaturated fats may be further classified as monounsaturated (one double-bond) or polyunsaturated (many double-bonds). ‘Trans’ fats are a type of unsaturated fat with trans-isomer fatty acid(s), typically created in an industrial process called (partial) hydrogenation. In humans, multiple studies have shown that unsaturated fats are to be preferred for health reasons, particularly mono-unsaturated fats. Saturated fats, typically from animal sources, are next, while trans fats are to be avoided. Saturated and trans fats are typically solid at room temperature (such as butter or lard), while unsaturated fats are typically liquids (such as olive oil or flaxseed oil). Trans fats are very rare in nature, but have properties useful in the food processing industry.
Essential fatty acids
Most fatty acids are non-essential, meaning the body can produce them as needed from other fats and some energy. However, in humans, at least two fatty acids are essential and must be consumed in the diet. An appropriate balance of essential fatty acids – omega-3 and omega-6 fatty acids – has been discovered to be important in reducing risk of some chronic diseases and conditions. Both of these “omega” long-chain polyunsaturated fatty acids are substrates for a class of eicosanoids known as prostaglandins which have uses throughout the human body; they are in some respects, hormones. The omega-3 eicosapentaenoic acid (EPA) (which can be made in the human body from the omega-3 essential fatty acid alpha-linolenic acid (LNA), or taken in through marine food sources), serves as a building block for series 3 prostaglandins (e.g. weakly-inflammation PGE3). The omega-6 dihomo-gamma-linolenic acid (DGLA) serves as a building block for series 1 prostaglandins (e.g. anti-inflammatory PGE1), whereas arachidonic acid (AA) serves as a building block for series 2 prostaglandins (e.g. pro-inflammatory PGE 2). Both DGLA and AA can be made from the omega-6 linoleic acid (LA) in the human body, or can be taken in directly through food. An appropriately balanced intake of omega-3 and omega-6 partly determines the relative production of different prostaglandins, which partly explains the importance of omega-3/omega-6 balance for cardiovascular health. In industrialised societies, people typically consume large amounts of processed vegetable oils that have reduced amounts of the essential fatty acids along with a too high ratio of omega-6 fatty acids relative to omega-3 fatty acids.
The conversion rate of omega-6 DGLA to AA largely determines the production of the respective prostaglandins PGE1 and PGE2. Omega-3 EPA prevents AA from being released from membranes, thereby skewing prostaglandin balance away from pro-inflammatory PGE2 made from AA toward anti-inflammatory PGE1 made from DGLA. Moreover, the conversion (desaturation) of DGLA to AA is controlled by the enzyme delta-5-desaturase, which in turn is controlled by hormones such as insulin (up-regulation) and glucagon (down-regulation). Because the amount and type of glucose and starch )plus some amino acid types) in food affect insulin, glucagon and other hormones, not only the amount of omega-3 versus omega-6 eaten but also the general composition of the diet, are implicated in general health regarding the essential fatty acids, inflammation (e.g. immune function) and mitosis (i.e. cell division).
Good sources of essential fatty acids are most vegetables, nuts/seeds and marine oils,[2] including: fish, flax seed oils, soy beans, pumpkin seeds, sunflower seeds, and walnuts.
Fibre
< 17 J/g (< 4 cal/g)
Fibre is a carbohydrate that is incompletely absorbed in humans and some animals. Like all carbohydrates, it contains four calories per gram, but due to its limited absorption, it contributes fewer calories. Dietary fiber consists mainly of cellulose, a large carbohydrate polymer, that is indigestible because humans do not have enzymes to digest it. There are two subcategories: soluble and insoluble fiber. The first dissolves in water; the second does not. Whole grains, fruits (especially plums, prunes, and figs), and vegetables are rich in dietary fiber. Fibre is important to digestive health and is thought to reduce the risk of colon cancer. It can benefit both constipation and diarrhea. Fibers provide bulk to the intestinal contents, and insoluble fiber stimulates peristalsis, the rhythmic muscular contractions passing along the digestive tract). Soluble fibres, especially those with high viscosity, absorb water to form a gel that slows the movement of food through the intestines. Fibre, especially that in whole grains, may help lessen insulin spikes and reduce the risk of diabetes.
Protein
Most meats such as chicken contain all the essential amino acids needed for humans.
17 J/g (4 cal/g)
Proteins are the basis of animal body structures (eg, muscles, skin, hair etc.). They are composed of amino acids, sometimes many thousands, which are characterized by inclusion of nitrogen and sometimes sulphur. The body requires amino acids to produce new body protein (protein retention) and to replace damaged proteins (maintenance). Amino acids not needed are discarded, typically in the urine. In animals, amino acid requirements are classified in terms of essential (an animal cannot produce them internally) and non-essential (the animal can produce them from other nitrogen containing compounds) amino acids. Humans use about 20 amino acids, and about ten are essential in this sense. Consuming a diet that contains adequate amounts of essential (but also non-essential) amino acids is particularly important for growing, pregnant, nursing, or injured animals, all of whom have a particularly high requirement. Protein nutrition which contains the essential amino acids is a complete protein source, one missing one or more is called incomplete. It’s possible to combine two incomplete protein sources (eg, rice and beans) to make a complete protein source. Dietary sources of protein include meats, tofu and other soy-products, eggs, grains, legumes, and dairy products such as milk and cheese. A few amino acids from protein can be converted into glucose and used for fuel through a process called gluconeogenesis. The remaining amino acids are discarded.
Minerals
Dietary minerals are the chemical elements required by living organisms, other than the four elements carbon, hydrogen, nitrogen, and oxygen which are present in common organic molecules. The term “mineral” is archaic, since the intent of the definition is to describe ions, not chemical compounds or actual minerals. Some dietitians recommend that these heavier elements should be supplied by ingesting specific foods (that are enriched in the element(s) of interest), compounds, and sometimes including even minerals, such as calcium carbonate. Sometimes these “minerals” come from natural sources such as ground oyster shells. Sometimes minerals are added to the diet separately from food, such as mineral supplements, the most famous being iodine in “iodized salt”.
Macrominerals
A variety of elements are required to support the biochemical processes, many play a role as electrolytes or in a structural role.[3] In human nutrition, the dietary bulk “mineral elements” (RDA > 200 mg/day) are in alphabetical order (parenthetical comments on folk medicine perspective):
• Calcium (for muscle and digestive system health, builds bone, neutralizes acidity, clears toxins, helps blood stream)
• Chloride
• Magnesium required for processing ATP and related reactions (health, builds bone, causes strong peristalsis, increases flexibility, increases alkalinity)
• Phosphorus required component of bones (see apatite) and energy processing and many other functions (bone mineralization)[4]
• Potassium required electrolyte (heart and nerves health)
• Sodium electrolyte
• Sulfur for three essential amino acids and many proteins and cofactors (skin, hair, nails, liver, and pancreas health)
Trace minerals
A variety of elements are required in trace amounts, usually because they play a role in catalysis in enzymes.[5] Some trace mineral elements (RDA < 200 mg/day) are (alphabetical order):
• Cobalt required for biosynthesis of vitamin B12 family of coenzymes
• Copper required component of many redox enzymes, including cytochrome c oxidase
• Chromium required for sugar metabolism
• Iodine required for the biosynthesis of thyroxin
• Iron required for many proteins and enzymes, notably hemoglobin
• Manganese (processing of oxygen)
• Molybdenum required for xanthine oxidase and related oxidases
• Nickel present in urease
• Selenium required for peroxidase (antioxidant proteins)
• Vanadium (There is no established RDA for vanadium. No specific biochemical function has been identified for it in humans, although vanadium is found in lower organisms.)
• Zinc required for several enzymes such as carboxypeptidase, liver alcohol dehydrogenase, carbonic anhydrase. Zinc is pervasive.
Iodine is required in larger quantities than the other trace minerals in this list and is sometimes classified with the bulk minerals. Sodium is not generally found in dietary supplements, despite being needed in large quantities, because the ion is very common in food.
Vitamins
Mineral and/or vitamin deficiency or excess may result in disease conditions such as goitre, scurvy, osteoporosis, impaired immune system, disorders of cell metabolism, certain forms of cancer, symptoms of premature aging, and poor psychological health (including eating disorders), among many others.
As of 2005, twelve vitamins and about the same number of minerals are recognized as “essential nutrients”, meaning that they must be consumed and absorbed—or, in the case of vitamin D, alternatively synthesized in the skin via UVB radiation to prevent deficiency symptoms and possibly death. Certain vitamin-like substances found in foods, such as carnitine, have also been found essential to survival and health, but these are not strictly “essential” to eat because the human body can produce them from other compounds. Moreover, thousands of different phytochemicals have recently been discovered in food (particularly in fresh vegetables), which may have desirable properties including antioxidant activity (see below). Other essential nutrients include essential amino acids, choline and the essential fatty acids.
Water
About 70% of the non-fat mass of the human body is made of water.[citation needed] To function properly, the body requires between one and seven liters of water per day to avoid dehydration; the precise amount depends on the level of activity, temperature, humidity, and other factors.[citation needed] With physical exertion and heat exposure, water loss will increase and daily fluid needs may increase as well.
It is not clear how much water intake is needed by healthy people, although some experts assert that 8–10 glasses of water (approximately 2 liters) daily is the minimum to maintain proper hydration.[7] The notion that a person should consume eight glasses of water per day cannot be traced back to a scientific source.[8] The effect of water intake on weight loss and on constipation is also still unclear.[9] Original recommendation for water intake in 1945 by the Food and Nutrition Board of the National Research Council read: “An ordinary standard for diverse persons is 1 milliliter for each calorie of food. Most of this quantity is contained in prepared foods.”[10] The latest dietary reference intake report by the United States National Research Council in general recommended (including food sources): 2.7 liters of water total for women and 3.7 liters for men.[11] Specifically, pregnant and breastfeeding women need additional fluids to stay hydrated. According to the Institute of Medicine—who recommend that, on average, women consume 2.2 litres and men 3.0 litres—this is recommended to be 2.4 litres (approx. 9 cups) for pregnant women and 3 litres (approx. 12.5 cups) for breastfeeding women since an especially large amount of fluid is lost during nursing.[12]
For those who have healthy kidneys, it is rather difficult to drink too much water,[citation needed] but (especially in warm humid weather and while exercising) it is dangerous to drink too little. People can drink far more water than necessary while exercising, however, putting them at risk of water intoxication, which can be fatal. In particular large amounts of de-ionized water are dangerous.
Normally, about 20 percent of water intake comes in food, while the rest comes from drinking water and assorted beverages (caffeinated included). Water is excreted from the body in multiple forms; including urine and feces, sweating, and by water vapor in the exhaled breath.
Other nutrients
Other micronutrients include antioxidants and phytochemicals. These substances are generally more recent discoveries which: have not yet been recognized as vitamins; are still under investigation; or contribute to health but are not necessary for life. Phytochemicals may act as antioxidants, but not all phytochemicals are antioxidants.
Antioxidants
Antioxidants are a recent discovery. As cellular metabolism/energy production requires oxygen, potentially damaging (e.g. mutation causing) compounds known as free radicals can form. Most of these are oxidizers (i.e. acceptors of electrons) and some react very strongly. For normal cellular maintenance, growth, and division, these free radicals must be sufficiently neutralized by antioxidant compounds. Some are produced by the human body with adequate precursors (glutathione, Vitamin C) and those that the body cannot produce may only be obtained through the diet through direct sources (Vitamin C in humans, Vitamin A, Vitamin K) or produced by the body from other compounds (Beta-carotene converted to Vitamin A by the body, Vitamin D synthesized from cholesterol by sunlight). Phytochemicals (Section Below) and their subgroup polyphenols are the majority of antioxidants; about 4,000 are known. Different antioxidants are now known to function in a cooperative network, e.g. vitamin C can reactivate free radical-containing glutathione or vitamin E by accepting the free radical itself, and so on. Some antioxidants are more effective than others at neutralizing different free radicals. Some cannot neutralize certain free radicals. Some cannot be present in certain areas of free radical development (Vitamin A is fat-soluble and protects fat areas, Vitamin C is water soluble and protects those areas). When interacting with a free radical, some antioxidants produce a different free radical compound that is less dangerous or more dangerous than the previous compound. Having a variety of antioxidants allows any byproducts to be safely dealt with by more efficient antioxidants in neutralizing a free radical’s butterfly effect.
Phytochemicals
Blackberries are a source of polyphenol antioxidants
A growing area of interest is the effect upon human health of trace chemicals, collectively called phytochemicals. These nutrients are typically found in edible plants, especially colorful fruits and vegetables, but also other organisms including seafood, algae, and fungi. The effects of phytochemicals increasingly survive rigorous testing by prominent health organizations. One of the principal classes of phytochemicals are polyphenol antioxidants, chemicals which are known to provide certain health benefits to the cardiovascular system and immune system. These chemicals are known to down-regulate the formation of reactive oxygen species, key chemicals in cardiovascular disease.
Perhaps the most rigorously tested phytochemical is zeaxanthin, a yellow-pigmented carotenoid present in many yellow and orange fruits and vegetables. Repeated studies have shown a strong correlation between ingestion of zeaxanthin and the prevention and treatment of age-related macular degeneration (AMD).[13] Less rigorous studies have proposed a correlation between zeaxanthin intake and cataracts.[14] A second carotenoid, lutein, has also been shown to lower the risk of contracting AMD. Both compounds have been observed to collect in the retina when ingested orally, and they serve to protect the rods and cones against the destructive effects of light.
Another carotenoid, beta-cryptoxanthin, appears to protect against chronic joint inflammatory diseases, such as arthritis. While the association between serum blood levels of beta-cryptoxanthin and substantially decreased joint disease has been established, neither a convincing mechanism for such protection nor a cause-and-effect have been rigorously studied.[15] Similarly, a red phytochemical, lycopene, has substantial credible evidence of negative association with development of prostate cancer.The correlations between the ingestion of some phytochemicals and the prevention of disease are, in some cases, enormous in magnitude.Even when the evidence is obtained, translating it to practical dietary advice can be difficult and counter-intuitive. Lutein, for example, occurs in many yellow and orange fruits and vegetables and protects the eyes against various diseases. However, it does not protect the eye nearly as well as zeaxanthin, and the presence of lutein in the retina will prevent zeaxanthin uptake. Additionally, evidence has shown that the lutein present in egg yolk is more readily absorbed than the lutein from vegetable sources, possibly because of fat solubility.[16] At the most basic level, the question “should you eat eggs?” is complex to the point of dismay, including misperceptions about the health effects of cholesterol in egg yolk, and its saturated fat content. As another example, lycopene is prevalent in tomatoes (and actually is the chemical that gives tomatoes their red color). It is more highly concentrated, however, in processed tomato products such as commercial pasta sauce, or tomato soup, than in fresh “healthy” tomatoes. Yet, such sauces tend to have high amounts of salt, sugar, other substances a person may wish or even need to avoid.
The following table presents phytochemical groups and common sources, arranged by family:
Family Sources Possible Benefits
flavonoids
berries, herbs, vegetables, wine, grapes, tea
general antioxidant, oxidation of LDLs, prevention of arteriosclerosis and heart disease
isoflavones (phytoestrogens)
soy, red clover, kudzu root
general antioxidant, prevention of arteriosclerosis and heart disease, easing symptoms of menopause, cancer prevention[17]
isothiocyanates
cruciferous vegetables
cancer prevention
monoterpenes
citrus peels, essential oils, herbs, spices, green plants, atmosphere[18]
cancer prevention, treating gallstones
organosulfur compounds
chives, garlic, onions
cancer prevention, lowered LDLs, assistance to the immune system
saponins
beans, cereals, herbs
Hypercholesterolemia, Hyperglycemia, Antioxidant, cancer prevention,
Anti-inflammatory
capsaicinoids
all capiscum (chile) peppers
topical pain relief, cancer prevention, cancer cell apoptosis
Intestinal bacterial flora
Main article: Gut flora
It is now also known that animal intestines contain a large population of gut flora. In humans, these include species such as Bacteroides, L. acidophilus and E. coli, among many others. They are essential to digestion, and are also affected by the food we eat. Bacteria in the gut perform many important functions for humans, including breaking down and aiding in the absorption of otherwise indigestible food; stimulating cell growth; repressing the growth of harmful bacteria, training the immune system to respond only to pathogens; producing vitamin B12, and defending against some infectious diseases.
Malnutrition
Malnutrition refers to insufficient, excessive, or imbalanced consumption of nutrients. In developed countries, the diseases of malnutrition are most often associated with nutritional imbalances or excessive consumption. Although there are more people in the world who are malnourished due to excessive consumption, according to the United Nations World Health Organization, the real challenge in developing nations today, more than starvation, is combating insufficient nutrition — the lack of nutrients necessary for the growth and maintenance of vital functions.
Illnesses caused by improper nutrient consumption
NUTRIENTS DEFICIENCY EXCESS
Energy
Starvation
Obesity, diabetes mellitus, Cardiovascular disease
Simple carbohydrates
Marasmus, starvation
diabetes mellitus
Complex carbohydrates
Marasmus, starvation
Obesity
Saturated fat / trans fat
none Cardiovascular disease,
Unsaturated fat
Rabbit starvation
Obesity
Cholesterol
none Cardiovascular disease
Protein
Marasmus
Ketoacidosis, Rabbit starvation, kidney disease
Sodium
hyponatremia
Hypernatremia, hypertension
Iron
Anemia
cirrhosis, heart disease
Iodine
Goiter, hypothyroidism
Iodine Toxicity (goiter, hypothyroidism)
Vitamin A
Xerophthalmia and Night Blindness Hypervitaminosis A (cirrhosis, hair loss, birth defects)
Vitamin B1
Beri-Beri
Vitamin B2
Cracking of skin and Corneal Unclearation
Niacin
Pellagra
dyspepsia, cardiac arrhythmias, birth defects
Vitamin B12
Pernicious Anemia
Vitamin C
Scurvy
diarrhea causing dehydration
Vitamin D
Rickets
Hypervitaminosis D (dehydration, vomiting, constipation)
Vitamin E
Hypervitaminosis E (anticoagulant: excessive bleeding)
Vitamin K
Hemorrhage
Processed foods
Since the Industrial Revolution some two hundred years ago, the food processing industry has invented many technologies that both help keep foods fresh longer and alter the fresh state of food as they appear in nature. Cooling is the primary technology used to maintain freshness, whereas many more technologies have been invented to allow foods to last longer without becoming spoiled. These latter technologies include pasteurisation, autoclavation, drying, salting, and separation of various components, and all appear to alter the original nutritional contents of food. Pasteurisation and autoclavation (heating techniques) have no doubt improved the safety of many common foods, preventing epidemics of bacterial infection. But some of the (new) food processing technologies undoubtedly have downfalls as well.
Modern separation techniques such as milling, centrifugation, and pressing have enabled concentration of particular components of food, yielding flour, oils, juices and so on, and even separate fatty acids, amino acids, vitamins, and minerals. Inevitably, such large scale concentration changes the nutritional content of food, saving certain nutrients while removing others. Heating techniques may also reduce food’s content of many heat-labile nutrients such as certain vitamins and phytochemicals, and possibly other yet to be discovered substances.[40] Because of reduced nutritional value, processed foods are often ‘enriched’ or ‘fortified’ with some of the most critical nutrients (usually certain vitamins) that were lost during processing. Nonetheless, processed foods tend to have an inferior nutritional profile compared to whole, fresh foods, regarding content of both sugar and high GI starches, potassium/sodium, vitamins, fibre, and of intact, unoxidized (essential) fatty acids. In addition, processed foods often contain potentially harmful substances such as oxidized fats and trans fatty acids.
A dramatic example of the effect of food processing on a population’s health is the history of epidemics of beri-beri in people subsisting on polished rice. Removing the outer layer of rice by polishing it removes with it the essential vitamin thiamine, causing beri-beri. Another example is the development of scurvy among infants in the late 1800s in the United States. It turned out that the vast majority of sufferers were being fed milk that had been heat-treated (as suggested by Pasteur) to control bacterial disease. Pasteurisation was effective against bacteria, but it destroyed the vitamin C.
As mentioned, lifestyle- and obesity-related diseases are becoming increasingly prevalent all around the world. There is little doubt that the increasingly widespread application of some modern food processing technologies has contributed to this development. The food processing industry is a major part of modern economy, and as such it is influential in political decisions (e.g. nutritional recommendations, agricultural subsidising). In any known profit-driven economy, health considerations are hardly a priority; effective production of cheap foods with a long shelf-life is more the trend. In general, whole, fresh foods have a relatively short shelf-life and are less profitable to produce and sell than are more processed foods. Thus the consumer is left with the choice between more expensive but nutritionally superior whole, fresh foods, and cheap, usually nutritionally inferior processed foods. Because processed foods are often cheaper, more convenient (in both purchasing, storage, and preparation), and more available, the consumption of nutritionally inferior foods has been increasing throughout the world along with many nutrition-related health complications.
