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Lecture 13

FDSC 200 Lecture 13: Chapter 13

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Food Science
FDSC 200
Lawrence Goodridge

FDSC 200 Chapter 13 The Micronutrients: Vitamins and Minerals Vitamins • Vitamins are organic compounds (have a carbon backbone of at least 2 carbons) needed in small amounts in the diet to help regulate body processes o Main role: work as components in enzymes systems to maintain health. ✓ They are not a source of energy. o Enzyme reactions are slowed or stopped and body processes impaired if vitamins are missing. Many vitamins can act as co-enzymes in order for enzymes to interact with the substrates. If they are missing, the enzyme cannot interact with the substrate and no reaction is occurring. • Scientists gave vitamins names, letters, or numbers to identify them ✓ For example, vitamin B1 is also known as thiamin. • Fat-soluble vitamins o have a nonpolar molecular structure and dissolve in fats and oils o Include vitamins A, D, E and K o They require bile from the liver for digestion, and once they are absorbed from the body, they are not easily excreted (water-soluble is the form in which compounds need to be in, in order to be excreted from the body) ✓ Any excess of fat-soluble vitamins are stored in the liver or in fatty tissues for future use– the body can use these excess stores of vitamins and survive off of them for weeks ✓ If you ingest Megadoses of fat-soluble vitamins, they can reach toxic levels in the body • Water-soluble vitamins o are polar and dissolve in water and water-based liquids o include the B vitamins and vitamin C o Whatever you do not need is expelled and will never build up in your body in storage because water-soluble is the form in which compounds are excreted in the body Fat-Soluble Vitamins 1. Vitamin A • The first vitamin to be identified • Functions: 1. Aids in night vision ✓ Vitamin A must be present in the retina, or else the cells at the back of the eye will not be able to react when stimulated by light 2. Maintains healthy skin and internal lining of lungs and digestive tract 3. Ensures proper immune system function and production and regulation of hormones 4. Breaks down bone for reshaping during growth ✓ Growing children NEED vitamin A for the normal development of bone tissue 5. Work in conjunction with protein, iron, and folic acid in order to form red blood cells • Vitamin A is found in 2 basic forms in food o 1. Retinol: yellow and active form of vitamin A and is found in liver, eggs, butter, milk, and cheese ✓ Retinol is needed for use by the human body but found in food ✓ Retinol is one of a group of compounds called retinoids or preformed vitamin A o 2. Beta-carotene: A precursor for retinol, found in orange and dark green fruits and vegetables ✓ Precursors: also known, as provitamins are chemical compounds that the body converts to the active forms of vitamins. ✓ It takes 3 units of beta-carotene to make 1 unit of retinol. So, when beta-carotene is converted to the active form, retinol, losses occur. ✓ Beta-carotene is high in…. 1. Bright orange vegetables: carrots, sweet potatoes, pumpkin, cantaloupe and apricots 2. Dark green vegetables: because beta-carotene combine with chlorophyll in vegetables to create a dark green color they are found in: spinach, collard greens, kale and broccoli. 2. Vitamin D • They body can make all it needs of vitamin D • Vitamin D is a fat-soluble vitamin • How it’s made: o When the skin is exposed to sunlight, a cholesterol compound in the skin can be converted to vitamin D precursors cholecalciferol (vitamin D3) and ergocalciferol (vitamin D2 – found in plant foods also) ✓ These vitamin D precursors will then be absorbed into the bloodstream from the skin, and converted to vitamin D in the liver and the kidneys. But, vitamin D precursors will only be converted to vitamin D when it is needed. o Teams with other nutrients ✓ Like calcium to regulate calcium levels and form bones and teeth. Vitamin D must be present to make calcium available to form bone (vitamin D is needed for calcium to be used to make bone) o Found in: butter, cream, egg yolks, and fatty fish and by exposing the skin to sunlight ✓ Vitamin D can also be added to milk in order to ensure people who do not get enough sunlight exposure have an adequate source of vitamin D in their body 3. Vitamin E • Oxidation is the chemical reaction in the body where oxygen reacts with other compounds, and the result can be damaging. This is why vitamin E is especially important, because it acts as an anti-oxidant in the body. o It works as an anti-oxidant that quickly reacts with oxygen, preventing damage to body tissues like red and white blood cells • Found in: vegetable oils, whole grains, avocados, nuts, and seeds o Vitamin E is not stable at high temperatures, so food sources that need to be cooked at high temperatures will have the vitamin E removed from the food source 4. Vitamin K • Functions: o Necessary for production of two proteins involved in blood clotting
 o Just like vitamin D, some vitamin K is provided by a non-food source ✓ Vitamin K can be made by gut-bacteria (bacteria in the intestine) as a waste product. Bacteria in your gut meet half of your daily vitamin K needs. o The other half of the vitamin K needs come from liver and dark leafy greens Water-Soluble Vitamins • These vitamins cannot be stored in the body since they dissolve in water o Excess quantities are excreted in urine because they are in their water-soluble form, making it impossible to receive toxic doses of water-soluble vitamins B-Complex Vitamins • B vitamins are absorbed best and work best all together, that is why they are most commonly found in all the same food sources. o If a person is deficient in one B vitamin, chances are they are probably deficient in many B vitamins. • Water-soluble B-complex vitamins
 o Act as coenzymes in reactions throughout the body ✓ A coenzyme is a non-protein that combines with an inactive enzyme to activate the enzyme system ✓ B vitamins are involved in the chemical reactions needed to release energy in food o Are found in leafy greens, legumes, pork, whole grains, eggs, fish, and milk • The B-complex vitamins specialize
 o Vitamin B1 (thiamin): helps the normal functioning of nerves and muscles they control o Vitamin B2 (riboflavin): promotes healthy skin and normal eyesight o Vitamin B3: keeps the skin and nervous system healthy and promotes normal digestion o Pantothenic acid: promotes growth and helps synthesize several vital substances o Biotin: helps the body make fats and glycogen o Vitamin B6 (pyridoxine): converts the amino acid tryptophan to niacin, promotes healthy immune and nervous systems and helps make hemoglobin ✓ Hemoglobin: the protein that allows red blood cells carry oxygen from the lungs to every cell o Folate: helps cells divide to form new cells and prevents neural tube damage ✓ Damage in neural tube in newborns can cause damages that can range from mental illnesses to death o Vitamin B12 (cobalamin): helps folate function ✓ Also helps promote the health of nerve tissue and red blood cell formation Vitamin C • Vitamin C is also known as ascorbic acid and is a water-soluble vitamin • Vitamin C functions: 1. Helps produce connective tissue collagen 2. Helps protect against infections
 3. Helps the body absorb iron and calcium 4. During times of stress, vitamin C helps with the release of adrenaline 5. Vitamin C is needed for a series of chemical reactions involved in the formation of bone and teeth 6. Serves as an antioxidant: will react with oxygen before it can react with any other compounds • Found in: citrus fruits, cantaloupe, tomatoes, strawberries, broccoli, cabbage and sweet peppers Non-Vitamins 1. Choline: was considered for the list of vitamins but later on rejected. Although it is made in small amounts by the body, we still do need to consume it in the diet to maintain good health. Although it is not a vitamin, it is still a bioactive compound that is considered to be an essential nutrient. 2. Coenzyme Q10: is needed for enzyme reactions, but it’s daily recommended intakes are still not established. Minerals • Minerals have the simplest structure of all nutrients because they are elements o Minerals make up about 2.3 kg of the average adult’s mass • They are grouped into 2 categories
 o Major minerals are needed in amounts of 100 mg or more per day ✓ They include: 1. Calcium 2. Phosphorus 3. Sodium 4. Potassium 5. Chloride 6. Magnesium 7. Sulfur o Trace minerals are needed in amounts of less than 100 mg per day Major Minerals 1. Calcium: 99% of calcium is found in bone and teeth; the remaining 1% plays a role in the body. • Functions of calcium: o Regulates the movement of ions across the cell membranes o Is important for sending messages along nerve fibers (nerve impulse transmission) o Helps maintain the body’s blood pressure o Must be present so muscles (like the heart muscle) are able to contract and relax o Is a catalyst in one of the steps of the blood clotting process • Foods high in calcium: o Milk (highest) o Sardines o Canned salmon o Vegetables: broccoli, kale, mustard greens, watercress, parsley and seaweed 2. Phosphorus: plays role that are critical for life. • Found in: most of body’s phosphorus is stored in bone tissue but it also plays a major role in the body • Food sources: most foods including soft drinks, therefore deficiencies are very uncommon. • Functions: o Works as a salt buffer in the body’s acid-base balance o As part of the genetic material of every cell o Found in compounds that extract energy from nutrients o Works with lipids to form cell membranes o Helps to regulate many enzymes 3. Sodium: main positive ion in maintaining body’s fluid balance • It is the main positive ion found outside the cells • Found in: about 10% of sodium occurs naturally in the food you eat, the rest of the sodium intake is from salt (NaCl) • Functions: o Helps regulate body temperature (primary mineral found in sweat) o Helps regulate the balance of fluids inside and outside of the cells • The kidneys filter excess sodium from the bloodstream of healthy people o However, there has been a link between high sodium intake and high blood pressure for sodium- sensitive people • Dietary Guidelines for recommended sodium intake: less than 2,300 mg per day o The daily intake of sodium should be less than 1,500 mg per day for people who… ✓ Are over the age of 51 years ✓ African-Americans ✓ Have specific diseases such as: hypertension, diabetes and chronic kidney disease • Sodium deficiency: is very common with excessive fluid loss (vomiting or diarrhea) but can be rapidly reversed with sodium intake. 4. Chloride: the main negative ion involved in maintaining fluid balance in the body • Salt (NaCl) is the primary source of chloride • Some vegetables may also contain chloride 5. Potassium: the main positive ion found inside of cells • Functions: o Helps regulate body temperature (along with sodium) o Plays a critical role in maintaining heartbeat o Potassium citrate: helps reduce bone loss and prevent kidney stones • Found in: all fresh foods o Meats o Milk o Fruits and vegetables o Grains 6. Magnesium: found in small amounts in the body, but these small amounts have various uses. • Functions: o Involved in hundreds of enzymatic reactions o Necessary for the use of vitamin D, K, Ca o Essential for bone health (calcium and magnesium need to be balanced at a 2:1 ratio) o Must be available before energy can be released for muscle contractions • Magnesium can be stored in the body, so deficiencies are highly unlikely. • Food sources: o Legumes o Whole grains o Dairy foods o Dark green vegetables 7. Sulfur: • Functions: o Helps maintain a normal acid-base balance in the body o Helps the liver change toxins into harmless s
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