Nutrition Facts!

Nutrition Facts! Ancient Greece: around 475 BC: Anaxagoras states that food is absorbed by the human body and therefore contained "homeomerics" (generative components), thereby deducing the existence of nutrients. around 400 BC: Hippocrates says, "Let food be your medicine and medicine be your food."

Nutrition Facts! The first recorded nutritional experiment is found in the Bible's Book of Daniel. Daniel and his friends were captured by the king of Babylon during an invasion of Israel. Selected as court servants, they were to share in the king's fine foods and wine but they objected, preferring vegetables and water in accordance with their Jewish dietary restrictions.

Nutrition Facts! The king's chief steward reluctantly agreed to a trial. Daniel and his friends received their diet for 10 days and were then compared to the king’s men. Appearing healthier, they were allowed to continue with their diet.

Nutrition Facts! 1500s: Scientist and artist Leonardo da Vinci compared human metabolism to a burning candle.

Nutrition Facts! 1747: Dr. James Lind, a physician in the British navy, performed the first scientific nutrition experiment. He discovered that lime juice saved sailors who had been at sea for years from scurvy, a deadly and painful bleeding disorder. The discovery was ignored for forty years, after which British sailors became known as "limeys."

Nutrition Facts! 1770: Antoine Lavoisier, the "Father of Nutrition and Chemistry" discovered the details of metabolism, demonstrating that the oxidation of food is the source of body heat.

Nutrition Facts! Early 1800’s: The elements carbon, nitrogen, hydrogen and oxygen were recognized as the primary components of food, and methods to measure their proportions were developed.

Nutrition Facts! 1816: Francois Magendie discovers that dogs fed only carbohydrates and fat lost their body protein and died in a few weeks, but dogs also fed protein survived, identifying protein as an essential dietary component.

Nutrition Facts! 1840: Justus Liebig discovers the chemical makeup of carbohydrates (sugars), fats (fatty acids) and proteins (amino acids).

Nutrition Facts! 1860’s: Claude Bernard discovers that body fat can be synthesized from carbohydrate and protein, showing that the energy in blood glucose can be stored as fat.

Nutrition Facts! The amount of food energy in a particular food could be measured by completely burning the dried food in a bomb calorimeter, a method known as direct calorimetry. However, the values given on food labels are not determined this way, because it overestimates the amount of energy that the human digestive system can extract, by also burning dietary fiber.

Nutrition Facts! Instead, standardized chemical tests and an analysis of the recipe are used to estimate the product's digestible constitutents (protein, carbohydrate, fat, etc.). These results are then converted into an equivalent energy value based on the following table:

Nutrition Facts! Food Component Energy (kcal/g) Fat 9 Ethanol (alcohol) 7 Proteins 4 Carbohydrates Organic Acids 3 Polyols (artificial sweeteners) 2.4

Nutrition Facts! Proteins are essential parts of all living organisms and participate in every process within cells. Many proteins are enzymes that catalyze biochemical reactions, and are vital to metabolism. Other proteins have structural or mechanical functions, such as maintaining cell shape. Proteins also play a role in immune responses.

Nutrition Facts! Proteins are also a necessary component in our diet, since animals can not synthesize all the amino acids and must obtain essential amino acids from food. Through the process of digestion, animals break down ingested protein into free amino acids that can be used for protein synthesis.

Nutrition Facts! An essential amino acid is one that cannot be made by the organism (usually referring to humans), and therefore must be supplied in the diet. Nine amino acids are generally regarded as essential for humans. They are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

Nutrition Facts! In addition, the amino acids arginine, cysteine, glycine and tyrosine are considered conditionally essential, meaning they are not normally required in the diet, but must be supplied to specific populations that do not synthesize it in adequate amounts.

Nutrition Facts! For example, patients living with phenylketonuria (PKU) must keep their intake of phenylalanine extremely low to prevent mental retardation. However, phenylalanine is the precursor for tyrosine synthesis. Without phenylalanine, tyrosine cannot be made and so tyrosine becomes essential in the diet of PKU patients.

Nutrition Facts! Some ingested amino acids, especially those that are not essential, are not used directly for protein biosynthesis. Instead, they are converted to carbohydrates, which is also used under starvation conditions to generate glucose from the body's own proteins, particularly those found in muscle.

Nutrition Facts! Carbohydrates require less water to digest than proteins or fats and are the most common source of energy. (Proteins and fats are vital building components for body tissue and cells, although can be converted to energy as well.) The World Health Organization recommends that national dietary guidelines set a goal of 55-75% of total energy from carbohydrates each day.

Nutrition Facts! Fats (also known as lipids) help to **maintain healthy skin and hair **insulate body organs against shock **maintain body temperature **serve as energy stores for the body (especially heart and skeletal muscle)

Nutrition Facts! Other substances found in food (water, non- digestible fiber, minerals, vitamins) do not contribute to the energy value of foods. As a rough guideline, recommended daily energy intake values for young adults are: 2500 kcal/day for men and 2000 kcal/day for women. Children, sedentary and older people require less energy. Physically active people require more energy.

Nutrition Facts! Human fat tissue contains about 87% lipids, so that 1 kg of body-fat tissue has roughly the caloric energy of 870 g of pure fat, or 7800 kcal. Therefore one has to create a 7800 kcal deficit between energy intake and use to lose 1 kg of body-fat. (In U.S. units, that is about 3500 kcal per pound.) http://www.wsgfl.org.uk/schools/sackville_www/ISTSackville/video/video1.htm