Nutrition for human body

Human nutrition deals with the provision of essential nutrients in food that are necessary to support human life and health. Generally, people can survive up to 40 days without food, a period largely dependent on the amount of water consumed, stored body fat, muscle mass and genetic factors.

Poor nutrition is a chronic problem often linked to poverty, a poor understanding of nutrition and dietary practices, and deficient sanitation and food security.Malnutrition and its consequences are large contributors to deaths and disabilities worldwide.Good nutrition helps children grow physically, promotes human biological development and helps in the eradication of poverty.

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 and RNA). These compounds consist of elements such as carbon, hydrogen, oxygen, nitrogen, phosphorus, calcium, iron, zinc, magnesium, manganese, and so on. All the chemical compounds and elements contained in the human body occur in various forms and combinations such as hormones, vitamins, phospholipids and hydroxyapatite. These compounds may be found in the human body as well as in the various types of organisms that humans consume Any study done to determine nutritional status must take into account the state of the body before and after experiments, as well as the chemical composition of the whole diet and of all the materials excreted and eliminated from the body (including urine and feces). Comparing food to waste material can help determine the specific compounds and elements absorbed and metabolized by the body.[medical citation needed] The effects of nutrients may only be discernible over 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.

Details of nutrition in human body

The seven major classes of nutrients are carbohydrates, fats, fiber, minerals, proteins, vitamins, and water. These nutrient classes are categorized as either macronutrients or micronutrients (needed in small quantities). The macronutrients are carbohydrates, fats, fiber, proteins, and water.[5] The micronutrients are minerals and vitamins.[6] The macronutrients (excluding fiber and water) provide structural material (amino acids from which proteins are built, and lipids from which cell membranes and some signaling molecules are built), and energy. Some of the structural material can also be used to generate energy internally, and in either case it is measured in Joules or kilocalories (often called “Calories” and written with a capital ‘C’ to distinguish them from little ‘c’ calories). Carbohydrates and proteins provide 17 kJ approximately (4 kcal) of energy per gram, while fats provide 37 kJ (9 kcal) per gram though the net energy from either depends on such factors as absorption and digestive effort, which vary substantially from instance to instance. Vitamins, minerals, fiber, and water do not provide energy, but are required for other reasons. A third class of dietary material, fiber (i.e., nondigestible material such as cellulose), seems also to be required, for both mechanical and biochemical reasons, though the exact reasons remain unclear. For all age groups, males need to consume higher amounts of macronutrients than females. In general, intakes increase with age until the second or third decade of life. Molecules of carbohydrates and fats consist of carbon, hydrogen, and oxygen atoms. Carbohydrates range from simple monosaccharides (glucose, fructose, galactose) to complex polysaccharides (starch). Fats are triglycerides, made of assorted fatty acid monomers bound to a glycerol backbone. Some fatty acids, but not all, are essential in the diet: they cannot be synthesized in the body. Protein molecules contain nitrogen atoms in addition to carbon, oxygen, and hydrogen.The fundamental components of protein are nitrogen-containing amino acids, some of which are essential in the sense that humans cannot make them internally. Some of the amino acids are convertible (with the expenditure of energy) to glucose and can be used for energy production just as ordinary glucose. By breaking down existing protein, some glucose can be produced internally; the remaining amino acids are discarded, primarily as urea in urine. This occurs naturally when atrophy takes place, or during periods of starvation.

Grain products: rich sources of complex and simple carbohydrates Carbohydrates may be classified as monosaccharides, disaccharides or polysaccharides depending on the number of monomer (sugar) units they contain. They are a diverse group of substances, with a range of chemical, physical and physiological properties. They make up a large part of foods such as rice, noodles, bread, and other grain-based products, but they are not an essential nutrient, meaning a human does not need to eat carbohydrates.Monosaccharides contain one sugar unit, disaccharides two, and polysaccharides three or more. Monosaccharides include glucose, fructose and galactose. Disaccharides include sucrose, lactose, and maltose; purified sucrose, for instance, is used as table sugar. Polysaccharides, which include starch and glycogen, are often referred to as ‘complex’ carbohydrates because they are typically long multiple-branched chains of sugar units. The difference is that complex carbohydrates take longer to digest and absorb since their sugar units must be separated from the chain before absorption. The spike in blood glucose levels after ingestion of simple sugars is thought to be related to some of the heart and vascular diseases, which have become more common in recent times. Simple sugars form a greater part of modern diets than in the past, perhaps leading to more cardiovascular disease. The degree of causation is still not clear.[medical citation needed] Simple carbohydrates are absorbed quickly, and therefore raise blood-sugar levels more rapidly than other nutrients. However, the most important plant carbohydrate nutrient, starch, varies in its absorption. Gelatinized starch (starch heated for a few minutes in the presence of water) is far more digestible than plain starch, and starch which has been divided into fine particles is also more absorbable during digestion. The increased effort and decreased availability reduces the available energy from starchy foods substantially and can be seen experimentally in rats and anecdotally in humans. Additionally, up to a third of dietary starch may be unavailable due to mechanical or chemical difficulty.

A molecule of dietary fat typically consists of several fatty acids (containing long chains of carbon and hydrogen atoms), 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 depending on the detailed structure of the fatty acids involved.[citation needed] Saturated fats have all of the carbon atoms in their fatty acid chains bonded to hydrogen atoms, whereas unsaturated fats have some of these carbon atoms double-bonded, so their molecules have relatively fewer hydrogen atoms than a saturated fatty acid of the same length. Unsaturated fats may be further classified as monounsaturated (one double-bond) or polyunsaturated (many double-bonds). Furthermore, depending on the location of the double-bond in the fatty acid chain, unsaturated fatty acids are classified as omega-3 or omega-6 fatty acids. Trans fats are a type of unsaturated fat with trans-isomer bonds; these are rare in nature and in foods from natural sources; they are typically created in an industrial process called (partial) hydrogenation.[citation needed] Many studies have shown that consumption of unsaturated fats, particularly monounsaturated fats, is associated with better health in humans. Saturated fats, typically from animal sources, are next in order of preference, while trans fats are associated with a variety of disease and should be avoided. Saturated and some 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, such as rancidity resistance.[citation needed] Most fatty acids are not essential, meaning the body can produce them as needed, generally from other fatty acids and always by expending energy to do so. However, in humans, at least two fatty acids are essential and must be included in the diet. An appropriate balance of essential fatty acids – omega-3 and omega-6 fatty acids – seems also important for health, though definitive experimental demonstration has been elusive. Both of these “omega” long-chain polyunsaturated fatty acids are substrates for a class of eicosanoids known as prostaglandins, which have roles throughout the human body. They are hormones, in some respects. 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 inflammatory 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: one reason a balance between omega-3 and omega-6 is believed important for cardiovascular health. In industrialized societies, people typically consume large amounts of processed vegetable oils, which have reduced amounts of the essential fatty acids along with too much of omega-6 fatty acids relative to omega-3 fatty acids.

Dietary fiber is a carbohydrate, specifically a polysaccharide, which is incompletely absorbed in humans and in some animals. Like all carbohydrates, when it is metabolized, it can produce four Calories (kilocalories) of energy per gram, but in most circumstances, it accounts for less than that because of its limited absorption and digestibility. The two subcategories are insoluble and soluble fiber. Insoluble dietary fiber consists mainly of cellulose, a large carbohydrate polymer that is indigestible by humans, because humans do not have the required enzymes to break it down, and the human digestive system does not harbor enough of the types of microbes that can do so. Soluble dietary fiber comprises a variety of oligosaccharides, waxes, esters, resistant starches, and other carbohydrates that dissolve or gelatinize in water. Many of these soluble fibers can be fermented or partially fermented by microbes in the human digestive system to produce short-chain fatty acids which are absorbed and therefore introduce some caloric content.[medical citation needed] Whole grains, beans and other legumes, fruits (especially plums, prunes, and figs), and vegetables are good sources of dietary fiber. Fiber is important to digestive health and is thought to reduce the risk of colon cancer.[citation needed] For mechanical reasons, fiber can help in alleviating both constipation and diarrhea. Fiber provides bulk to the intestinal contents, and insoluble fiber especially stimulates peristalsis – the rhythmic muscular contractions of the intestines which move digesta along the digestive tract. Some soluble fibers produce a solution of high viscosity; this is essentially a gel, which slows the movement of food through the intestines. Additionally, fiber, perhaps especially that from whole grains, may help lessen insulin spikes and reduce the risk of type 2 diabetes.

Proteins are the basis of many animal body structures (e.g. muscles, skin, and hair) and form the enzymes which catalyse chemical reactions throughout the body. Each protein molecule is composed of amino acids which contain nitrogen and sometimes sulphur (these components are responsible for the distinctive smell of burning protein, such as the keratin in hair). The body requires amino acids to produce new proteins (protein retention) and to replace damaged proteins (maintenance). Amino acids are soluble in the digestive juices within the small intestine, where they are absorbed into the blood. Once absorbed, they cannot be stored in the body, so they are either metabolized as required or excreted in the urine. Proteins consist of amino acids in different proportions. The most important aspect and defining characteristic of protein from a nutritional standpoint is its amino acid composition.[16] Amino acids which an animal cannot synthesize on its own from smaller molecules are deemed essential. The synthesis of some amino acids can be limited under special pathophysiological conditions, such as prematurity in the infant or individuals in severe catabolic distress, and those are called conditionally essential.[16] A vegetarian diet can adequately supply protein, support pregnancy, childhood and athletic endeavors,[17] and lower the risk of cardiovascular disease and cancer.

Dietary minerals are the chemical elements required by living organisms, other than the four elements carbon, hydrogen, nitrogen, and oxygen that are present in nearly all organic molecules. The term “mineral” is archaic, since the intent is to describe simply the less common elements in the diet. Some are heavier than the four just mentioned – including several metals, which often occur as ions in the body. Some dietitians recommend that these be supplied from foods in which they occur naturally, or at least as complex compounds, or sometimes even from natural inorganic sources (such as calcium carbonate from ground oyster shells). Some are absorbed much more readily in the ionic forms found in such sources. On the other hand, minerals are often artificially added to the diet as supplements; the most well-known is likely iodine in iodized salt which prevents goiter.

Essential dietary minerals

  • Chlorine as chloride ions; very common electrolyte; see sodium, below.
  • Magnesium, required for processing ATP and related reactions (builds bone, causes strong peristalsis, increases flexibility, increases alkalinity). Approximately 50% is in bone, the remaining 50% is almost all inside body cells, with only about 1% located in extracellular fluid. Food sources include oats, buckwheat, tofu, nuts, caviar, green leafy vegetables, legumes, and chocolate
  • .Phosphorus, required component of bones; essential for energy processing. Approximately 80% is found in inorganic portion of bones and teeth. Phosphorus is a component of every cell, as well as important metabolites, including DNA, RNA, ATP, and phospholipids. Also important in pH regulation. Food sources include cheese, egg yolk, milk, meat, fish, poultry, whole-grain cereals, and many others. Potassium, a very common electrolyte (heart and nerve health). With sodium,
  • potassium is involved in maintaining normal water balance, osmotic equilibrium, and acid-base balance. In addition to calcium, it is important in the regulation of neuromuscular activity. Food sources include bananas, avocados, vegetables, potatoes, legumes, fish, and mushrooms.
  • Sodium, a very common electrolyte; not generally found in dietary supplements, despite being needed in large quantities, because the ion is very common in food: typically as sodium chloride, or common salt.

Trace minerals

Many elements are required in smaller amounts (microgram quantities), usually because they play a catalytic role in enzymes. Some trace mineral elements (RDA < 200 mg/day) are, in alphabetical order:

  • Cobalt as a component of the vitamin B12 family of coenzymes
  • Copper required component of many redox enzymes, including cytochrome c oxidase
  • Chromium required for sugar metabolism
  • Iodine required not only for the biosynthesis of thyroxin, but probably, for other important organs as breast, stomach, salivary glands, thymus etc. (see Iodine deficiency); for this reason iodine is needed in larger quantities than others in this list, and sometimes classified with the macrominerals; It can be found in ionized salt
  • Iron required for many enzymes, and for hemoglobin and some other proteins
  • Manganese (processing of oxygen)
  • Molybdenum required for xanthine oxidase and related oxidases
  • Selenium required for peroxidase (antioxidant proteins)
  • Zinc required for several enzymes such as carboxypeptidase, liver alcohol dehydrogenase, carbonic anhydrase

As with the minerals discussed above, some vitamins are recognized as essential nutrients, necessary in the diet for good health. (Vitamin D is the exception: it can alternatively be synthesized in the skin, in the presence of UVB radiation.) Certain vitamin-like compounds that are recommended in the diet, such as carnitine, are thought useful for survival and health, but these are not “essential” dietary nutrients because the human body has some capacity to 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 ; experimental demonstration has been suggestive but inconclusive. Other essential nutrients not classed as vitamins include essential amino acids (see above), essential fatty acids , and the minerals discussed in the preceding section.[medical citation needed] Vitamin deficiencies may result in disease conditions: goiter, 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.

Protein 64 g/day*
(Including plain water, milk and other drinks)
2.3 L/day**
Fibre 30 g/day**
Vitamin A 900 μg/day of retinol equivalents
Thiamin 1.2 mg/day*
Riboflavin 1.3 mg/day*
Niacin 16 mg/day of niacin equivalents
Vitamin B6 1.3 mg/day*
Vitamin B12 2.4 μg/day*
Folate 400 μg/day as dietary folate equivalents
Vitamin C 45 mg/day*
Calcium 1000 mg/day*
Iodine 150 μg/day*
Iron 8 mg/day*
Magnesium 400 mg/day*
Potassium 3800 mg/day*
Sodium 460-920 mg/day*
Zinc 14 mg/day*

Recommended Daily Allowances (RDA)- Nutrition person wise

Daily Intake Levels

Nutrient Quantity Per Day
Energy 8,700 kilojoules
Protein 50 grams
Fat 70 grams
Saturated Fatty Acids 24 grams
Carbohydrates 310 grams
Sugars 90 grams
Sodium (salt) 2.3 grams
Dietary Fibre 30 grams
Recommended Daily Allowances (RDA) Chart for Infants & Children
NUTRIENT 0-6 mths 7-12mths 1-3 yrs 4-8 yrs
RDA Vitamins (Per Day)
vitamin A – retinol 400* µg 500* µg 300 µg 400 µg
vitamin C – ascorbic acid 40* mg 50* mg 15 mg 25 mg
vitamin D  #1 5* µg 5* µg 5* µg 5* µg
vitamin E 4* mg 5* mg 6 mg 7 mg
vitamin K 2.0* µg 2.5* µg 30* µg 55* µg
vitamin B1 – thiamin 0.2* mg 0.3* mg 0.5 mg 0.6 mg
vitamin B2 – riboflavin 0.3* mg 0.4* mg 0.5 mg 0.6 mg
vitamin B3 – niacin 2* mg 4* mg 6 mg 8 mg
vitamin B5 – pantothenic acid 1.7* mg 1.8* mg 2* mg 3* mg
vitamin B6 – pyridoxine 0.1* mg 0.3* mg 0.5 mg 0.6 mg
vitamin B12 – cyanocobalamin 0.4* µg 0.5* µg 0.9 µg 1.2 µg
biotin 5* µg 6* µg 8* µg 12* µg
choline 125* mg 150* mg 200* mg 250* mg
folate – folic acid 65* µg 80* µg 150 µg 200 µg
Recommended Daily Allowances for Minerals
calcium 210* mg 270* mg 500* mg 800* mg
chromium 0.2* µg 5.5* µg 11* µg 15* µg
copper 200* µg 220* µg 340 µg 440 µg
fluoride >0.01* mg 0.5* mg 0.7* mg 1* mg
iodine 110* µg 130* µg 90 µg 90 µg
iron 0.27* mg 11 mg 7 mg 10 mg
magnesium 30* mg 75* mg 80 mg 130 mg
manganese 0.003* mg 0.6* mg 1.2* mg 1.5* mg
molybdenum 2* µg 3* µg 17 µg 22 µg
phosphorus 100* mg 275* mg 460 mg 500 mg
selenium 15* µg 20* µg 20 µg 30 µg
zinc 2* mg 3 mg 3 mg 5 mg
potassium 0.4* g 0.7* g 3.0* g 3.8* g
sodium 0.12* g 0.37* g 1.0* g 1.2* g
chloride 0.18* g 0.57* g 1.5* g 1.9* g
Recommended Daily Allowances for Older Children (9 to 18 Years)
9-13 Yrs
14-18 Yrs
9-13 Yrs
14-18 Yrs
RDA Vitamins (Per Day)
vitamin A – retinol 600 µg 900 µg 600 µg 700 µg
vitamin C – ascorbic acid 45 mg 75 mg 45 mg 65 mg
vitamin D #1 5* µg 5* µg 5* µg 5* µg
vitamin E 11 mg 15 mg 11 mg 15 mg
vitamin K 60* µg 75* µg 60* µg 75* µg
vitamin B1 – thiamin 0.9 mg 1.2 mg 0.9 mg 1.0 mg
vitamin B2 – riboflavin 0.9 mg 1.3 mg 0.9 mg 1.0 mg
vitamin B3 – niacin 12 mg 16 mg 12 mg 14 mg
vitamin B5 – pantothenic acid 4* mg 5* mg 4* mg 5* mg
vitamin B6 – pyridoxine 1.0 mg 1.3 mg 1.0 mg 1.2 mg
vitamin B12 – cyanocobalamin 1.8 µg 2.4 µg 1.8 µg 2.4 µg
biotin 20* µg 25* µg 20* µg 25* µg
choline 375* mg 550* mg 375* mg 400* mg
folate – folic acid  #3 300 µg 400 µg 300 µg 400 µg
Recommended Daily Allowances for Minerals
calcium 1300* mg 1300* mg 1300* mg 1300* mg
chromium 25* µg 35* µg 21* µg 24* µg
copper 700 µg 890 µg 700 µg 890 µg
fluoride 2* mg 3* mg 2* mg 3* mg
iodine 120 µg 150 µg 120 µg 150 µg
iron 8 mg 11 mg 8 mg 15 mg
magnesium 240 mg 410 mg 240 mg 360 mg
manganese 1.9* mg 2.2* mg 1.6* mg 1.6* mg
molybdenum 34 µg 43 µg 34 µg 43 µg
phosphorus 1250 mg 1250 mg 1250 mg 1250 mg
selenium 40 µg 55 µg 40 µg 55 µg
zinc 8 mg 11 mg 8 mg 9 mg
potassium 4.5* g 4.7* g 4.5* g 4.7* g
sodium 1.5* g 1.5* g 1.5* g 1.5* g
chloride 2.3* g 2.3* g 2.3* g 2.3* g
Recommended Daily Allowances for Adults (19 Years and Up)
19-50 Yrs
>50 Yrs
19-50 Yrs
>50 Yrs
RDA Vitamins (Per Day)
vitamin A – retinol 900 µg 900 µg 700 µg 700 µg
vitamin C – ascorbic acid 90 mg 90 mg 75 mg 75 mg
vitamin D  #1 #5 5* µg 10* µg 5* µg 10* µg
vitamin E 15 mg 15 mg 15 mg 15 mg
vitamin K 120* µg 120* µg 90* µg 90* µg
vitamin B1 – thiamin 1.2 mg 1.2 mg 1.1mg 1.1 mg
vitamin B2 – riboflavin 1.3 mg 1.3 mg 1.1 mg 1.1 mg
vitamin B3 – niacin 16 mg 16 mg 14 mg 14 mg
vitamin B5 – pantothenic acid 5* mg 5* mg 5* mg 5* mg
vitamin B6 – pyridoxine 1.3 mg 1.7 mg 1.3 mg 1.5 mg
vitamin B12  #2 2.4 µg 2.4 µg 2.4 µg 2.4 µg
biotin 30* µg 30* µg 30* µg 30* µg
choline 550* mg 550* mg 425* mg 425* mg
folate – folic acid  #3 400 µg 400 µg 400 µg 400 µg
Recommended Daily Allowances for Minerals
calcium 1000* mg 1200* mg 1000* mg 1200* mg
chromium 35* µg 30* µg 25* µg 20* µg
copper 900 µg 900 µg 900 µg 900 µg
fluoride 4* mg 4* mg 3* mg 3* mg
iodine 150 µg 150 µg 150 µg 150 µg
iron 8 mg 8 mg 18 mg 8 mg
magnesium  #4 400/420 mg 420 mg 310/320 mg 320 mg
manganese 2.3* mg 2.3* mg 1.8* mg 1.8* mg
molybdenum 45 µg 45 µg 45 µg 45 µg
phosphorus 700 mg 700 mg 700 mg 700 mg
selenium 55 µg 55 µg 55 µg 55 µg
zinc 11 mg 11 mg 8 mg 8 mg
potassium 4.7* g 4.7* g 4.7* g 4.7* g
sodium  #5 1.5* g 1.3* g 1.5* g 1.3* g
chloride  #5 2.3* g 2.0* g 2.3* g 2.0* g
Recommended Daily Allowances for Pregnancy / Lactating Mothers
NUTRIENT Pregnancy
14-18 Yrs
19-50 Yrs
14-18 Yrs
19-50 Yrs
Recommended Daily Allowances for Vitamins
vitamin A – retinol 750 µg 770 µg 1200 µg 1300 µg
vitamin C – ascorbic acid 80 mg 85 mg 115 mg 120 mg
vitamin D  #1 5* µg 5* µg 5* µg 5* µg
vitamin E 15 mg 15 mg 19 mg 19 mg
vitamin K 75* µg 90* µg 75* µg 90* µg
vitamin B1 – thiamin 1.4 mg 1.4 mg 1.4 mg 1.4 mg
vitamin B2 – riboflavin 1.4 mg 1.4 mg 1.6 mg 1.6 mg
vitamin B3 – niacin 18 mg 18 mg 17 mg 17 mg
vitamin B5 – pantothenic acid 6* mg 6* mg 7* mg 7* mg
vitamin B6 – pyridoxine 1.9 mg 1.9 mg 2.0 mg 2.0 mg
vitamin B12 2.6 µg 2.6 µg 2.8 µg 2.8 µg
biotin 30* µg 30* µg 35* µg 35* µg
choline 450* mg 450* mg 550* mg 550* mg
folate – folic acid  #3 600 µg 600 µg 500 µg 500 µg
Recommended Daily Allowances for Minerals
calcium 1300* mg 1000* mg 1300* mg 1000* mg
chromium 29* µg 30* µg 44* µg 45* µg
copper 1000 µg 1000 µg 1300 µg 1300 µg
fluoride 3* mg 3* mg 3* mg 3* mg
iodine 220 µg 220 µg 290 µg 290 µg
iron 27 mg 27 mg 10 mg 9 mg
magnesium  #6 400 mg 350/360 mg 360 mg 310/320 mg
manganese 2.0* mg 2.0* mg 2.6* mg 2.6* mg
molybdenum 50 µg 50 µg 50 µg 50 µg
phosphorus 1250 mg 700 mg 1250 mg 700 mg
selenium 60 µg 60 µg 70 µg 70 µg
zinc 12 mg 11 mg 13 mg 12 mg
potassium 4.7* g 4.7* g 5.1* g 5.1* g
sodium 1.5* g 1.5* g 1.5* g 1.5* g
chloride 2.3* g 2.3* g 2.3* g 2.3* g