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Study of nutrients and other substances in foods and the body’s handling of them.
Foundation dependent on other fields: Biology, biochemistry, physiology.
Nutritional Genomics: a science studying the relationship between human genome, nutrition and health. It can be divided into two disciplines:
- nutrigenetics: studying of how genes affect the activities of
- nutrigenomics: studying how the nutrients affect the activities
Genome: full complement of genetic material in (DNA) in the chromosomes of a cell, carrying hereditary information for an individual organism. The human genome is composed of 23 pairs of chromosomes (46 in total)
97% of the genes known to be associated with human diseases result in monogenic diseases , i.e. a mutation in one gene is sufficient to cause the disease.
Modifying the dietary intake can prevent some monogenic diseases.
e.g. phenylkenonuria, a genetic disease with a defective phenylalanine hyroxylase enzyme, which is normally responsible for the metabolism of phenylalanine to tyrosine. This results in the accumulation of phenylalanine and its breakdown products in the blood and the decrease in tyrosine, which increases the risk of neurological damage and mental retardation. Phenylalanine-restricted tyrosine-supplemented diets are a means to nutritionally treat this monogenic disease.
In contrast , diseases currently in the world, e.g. obesity, cancer, diabetes, and cardiovascular diseases, are polygenic diseases , i.e. they arise from the dysfunction in a cascade of genes, and not from a single mutated gene.
Dietary intervention to prevent the onset of such diseases is a complex and ambitious goal.
Recently , it was discovered that the health effects of food compounds are related mostly to specific interactions on molecular level
i.e. dietary constituents participate in the regulation of gene expression by modulating the activity of transcription factors, or through the secretion of hormones that in turn interfere with a transcription factor.
Adult bone loss Cancer Infectious diseases Diabetes Hypertension Heart diseases Iron deficiency (anaemia) Vitamin deficiencies Mineral deficiencies Toxicities Poor resistance To disease Less nutrition- related (genetics) More nutrition- related
The Known 50 Essential Nutrients for Sustaining Human Life * *Numerous other beneficial substances in foods are also known to contribute to good health. Linoleic acid Linolenic acid Lipids-Fat (fatty acids) (2) A D E K C (Ascorbic acid) B 1 (Thiamin) B 2 (Riboflavin) B 3 (Pantothenic acid) Niacin B 6 (Pyridoxal) Folate Biotin B 12 (Cobalamin) Fe Zn Cu Mn I F B Se Mo Ni Cr V Si As Li Sn Co (in B 12 ) Na K Ca Mg S P Cl Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Threonine Tryptophan Valine Water Carbohydrates Vitamins (13) Micro-Elements (17) Macro-Minerals (7) Protein (amino acids) (9) Water & Energy (2)
The unit calorie has historically been used in two major alternate definitions that differ by a factor of 1000:
The small calorie, gram calorie , or calorie (symbol: cal ) is the amount of heat (energy) required to raise the temperature of one gram of water by 1 °C.
The large calorie, kilogram calorie, kilocalorie (symbol: kcal ), or Calorie (capital C ) is the amount of heat (energy) needed to increase the temperature of one kg of water by 1°C, exactly 1000 small calories, or about 4.184 kJ.
Meats and dairy products provide all the essential amino acids (derived only from food as body cannot manufacture. They perform various functions ) in a single food, but plant sources of protein do not.
Therefore, vegetarians should be careful to combine foods in a way that optimize essential amino acid availability
The Institute of Medicine recommends 130 grams (520 kilocalories) of carbohydrate per day, which is the average minimal usage of glucose by the brain.
The desirable range of carbohydrate intake is 45% to 65% of total caloric intake ( also referred to as the Acceptable Macronutrient Distribution Range, or AMDR ), and the Daily Value ( DV ) for carbohydrate on food labels is based on a recommended intake of 60% of total caloric consumption.
These recommendations also generally advise that no more than 25% of carbohydrate intake be derived from sugars (mono- and disaccharides)
The American Heart Association and the United States Department of Agriculture recommend that fat intake is limited to no more than 30% of daily calories: 10% or less of calories come from saturated fat, not more than 15% from monounsaturated fat, and less than 10% from polyunsaturated fat.
Saturated fats , which are generally solid at room temperature, are the least healthy and tend to increase the level of cholesterol in your blood.
Monounsaturated fats have been shown to raise the level of HDL , the 'good' cholesterol that protects against heart attacks.
Although polyunsaturated fats come from plants and fish, but they may be more likely to form free radicals and lead to tissue damage.
Act as regulators and assist in all body processes.
Some minerals serve as parts of body structures.
-Vitamins are essential for several enzymatic functions in human metabolism -Thiamine was discovered in 1912 and was thought to be a vital amine compound & thus the term vitamin was invented -13 vitamins are known, 4 fat soluble (KEDA) and 9 water soluble (C, Folate and the B group) .
Calcium (an important mineral for bone and tooth structure, blood clotting, and nerve transmission),
Phosphorus (combines with calcium-about two parts calcium for every part phosphorus- to produce healthy bones and teeth, plays an important role in energy metabolism),
Magnesium (essential for human metabolism and for maintaining the electrical potential in nerve and muscle cells),
Sodium (an essential mineral commonly referred to as salt. It is involved in body water balance and acid-base balance and is the major extracellular -outside the cell, including blood and fluid- mineral),
Chloride (an extracellular mineral that is essential for the maintenance of fluid balance and, therefore, normal cell function, also it is an important component of gastric juices) , and
Potassium (the main mineral found inside cells -an intracellular electrolyte- at a concentration that is 30 times greater than the concentration of potassium found outside cells. It is involved in water balance, nerve impulse transmission, and muscular contractions).