Nutrients That Protect DNA From Damage PDF

Nutrients That Protect DNA From Damage VITAMIN C Vitamin C, also known as L-ascorbic acid, is a water-soluble vitamin that is naturally present in some foods, added to others, and available as a dietary supplement. Humans, unlike most animals, are unable to synthesize vitamin C endogenou...

Nutrients That Protect DNA From Damage VITAMIN C Vitamin C, also known as L-ascorbic acid, is a water-soluble vitamin that is naturally present in some foods, added to others, and available as a dietary supplement. Humans, unlike most animals, are unable to synthesize vitamin C endogenously, so it is an essential dietary component  CONTD… The total body content of vitamin C ranges from 300 mg to about 2 g.  High levels of vitamin C (millimolar concentrations) are maintained in cells and tissues, and are highest in leukocytes (white blood cells), eyes, adrenal glands, pituitary gland, and brain. Relatively low levels of vitamin C (micromolar concentrations) are found in extracellular fluids, such as plasma, red blood cells, and saliva  ANTIOXIDATIVE ACTIVITY Ascorbic acid reacts with free radicals undergoing single-electron oxidation to produce a relatively poor reactive intermediate, the ascorbyl radical, which disproportionates to ascorbate and dehydro- ascorbate. Thus, ascorbic acid can reduce toxic, reactive oxygen species  Superoxide anion (O2 ) Hydroxyl radical (OH ), as well as Organic (RO2) Nitrogen (NO2 ) oxy radicals  Mechanism of Action High intracellular concentrations of vitamin C can prevent oxidation-induced mutations In the process of destroying free radicals, vitamin C turns into what's called a vitamin C radical. If certain metal ions are nearby, vitamin C radical can turn compounds called lipid hydro-peroxides into geno-toxins, which switch bases around in DNA, disrupting its delicate code. DIETARY SOURCES Citrus fruits, tomatoes, tomato juice and potatoes are major contributors of vitamin C.  Other good food sources include red and green peppers, kiwifruit, broccoli, strawberries, Brussels sprouts and cantaloupe. RECOMMENDED INTAKE The recommended daily allowance of vitamin C for adults is: 90 milligrams (mg) for males 75 mg for females 85 mg for pregnant women 120 mg for lactating women An additional 35 mg for people who smoke VITAMIN E Vitamin E, also known as α- Tocopherol, is a group of eight lipid- soluble compounds, tocopherols and tocotrienols synthesised by plants. α-Tocopherol accounts for 90% of the vitamin E in human tissues STRUCTURE ANTIOXIDANT ACTIVITY A lipid-soluble biological antioxidant and protects against lipid peroxidation Vitamin E participates as part of a multi- component system involving ascorbic acid, intracellular gluthathione, and the redox enzymes glutathione reductase and glutathione peroxidase. These functions appear to be involved in the roles of vitamin E in supporting cardiovascular health, immune function, and protection from exogenous sources of oxidative stress.  Mechanism of Action Lipid soluble Vitamin E prevents lipid peroxidation chain reactions in cellular membranes by interfering with the propagation of lipid radicals Vitamin E inhibits the UVAI induction of “light” and “dark” cyclobutane pyrimidine dimers, and oxidatively generated DNA damage Cyclo-butane Pyrimidine Dimers Ultraviolet (UV) radiation from the sun is the most common environmental carcinogen that leads to skin cancer in humans. UV causes the formation of pyrimidine dimers, cyclobutane pyrimidine dimers (CPDs) and pyrimidine-pyrimidone (6–4) photoproducts [(6– 4)PPs] between adjacent bases in DNA.  SOURCES Nuts, seeds, and vegetable oils are among the best sources of alpha-tocopherol, and significant amounts are available in green leafy vegetables and fortified cereals. Other excellent sources include animal products like cheese and eggs or plant oils.  SELENIUM Selenium is a trace element exists in two forms: inorganic (selenate and selenite) and organic (selenomethionine and selenocysteine. Most selenium is in the form of selenomethionine in animal and human tissues Skeletal muscle is the major site of selenium storage, accounting for approximately 28% to 46% of the total selenium pool  CONTD… Selenium is incorporated into glutathione peroxidase, an antioxidant enzyme that plays a critical role in reducing free-radicals and oxidation in the body. Selenium and vitamin E are synergistic antioxidants which means they work better together than separately.  Selenium can support the activity of vitamin E in limiting the oxidation of fats. Selenium also works with vitamin C, glutathione and vitamin B3 (niacin) to prevent oxygen molecules from becoming too reactive.  Mechanism of Action Aside from its antioxidant activity, selenium may also exhibit protection against DNA damage by increasing the activity of DNA repair enzymes, such as DNA glycosylases, and repair pathways that involve members, such as p53 and BRCA1 The p53 gene, is a tumor suppressor gene, i.e., its activity stops the formation of tumors. BRCA1 (BReast CAncer gene 1) and BRCA2 (BReast CAncer gene 2) are genes that produce proteins that help repair damaged DNA. Everyone has two copies of each of these genes —one copy inherited from each parent  SOURCES  Brazil nuts: 1 ounce provides 544 micrograms (mcg), or 777 percent of the daily recommended value (DV)  Tuna: 3 ounces of yellowfin tuna, cooked dry, contains 92 mcg, or 131 percent of DV  Halibut, baked: 3 ounces, cooked dry, contains 47 mcg, or 68 percent of DV  Brown rice, cooked: 1 cup contains 19 mcg  Egg: One large egg contains 15 mcg  Bread, white: 1 slice provides 10 mcg CAROTENOIDS Carotenoids are naturally occurring fat- soluble pigments that are synthesized by plants, algae and photosynthetic bacteria. Carotenoids can be broadly classified into two classes: carotenes e.g., beta-carotene and lycopene xanthophylls e.g., lutein and zeaxanthin. CLASSIFICATION Provitamin A carotenoids include  alpha carotene  beta carotene  beta cryptoxanthin.  Non-provitamin A carotenoids include  lutein,  zeaxanthin  lycopene  TYPES  Vitamin A from animal-derived foods is called retinol. This "pre-formed" vitamin A can be used directly by the body.  Good food sources of retinol vitamin A include beef and chicken liver, whole milk and cheese.  Vitamin A obtained from colorful fruits and vegetables is in the form of "provitamin A" carotenoids, which are converted to retinol by the body after the food is ingested.  Good food sources include carrots, sweet potatoes, spinach, kale  BETA CAROTENE Also known as provitamin A, because it is one of the most important precursors of vitamin A in the human diet. There are two ways in which beta- carotene can be converted to vitamin A:  Either by cleavage at the centre or by breaking the molecule down from one end  ABSORPTION The breakdown of beta-carotene occurs in the walls of the small intestine (intestinal mucosa) and is catalysed by the enzyme beta-carotene dioxygenase. The retinol formed is stored in the liver as retinyl esters as active vitamin A in times of need. Beta-carotene is fat-soluble, so you should take it with meals containing at least 3 g of fat to ensure absorption. INTAKE According to the National Institutes of Health, the recommended intake of beta-carotene is 3000 international units (IU) and 2310 IU for adult males and females respectively.  UNIQUE FEATURE  Carotenoid facilitates communication between cells by improving the expression of a gene that codes for connexin proteins.  These proteins form pores or gap junctions among cell membranes, thus allowing the cells to communicate through the exchange of small molecules.  It protects DNA by activating repair mechanisms. Sources Where does the RDA for Beta-Carotene come from? The Recommended Dietary Allowance (RDA) is the average daily requirement for a particular nutrient. With vitamin A the requirement is set in terms of retinol activity equivalents (RAE) The RDA for an adult male is 900μg RAE. The RDA for an adult female is 700μg, though can go as high as 1,300μg during lactation.  CONTD… For beta-carotene from foods 1μg RAE = 12μg beta-carotene. So the RDA for beta- carotene is equal to the RDA for RAE times 12. We use the 900mcg RDA to set the RDA for beta-carotene, so it is 900μg x 12 = 10800μg.  BENEFITS  Those who had macular degeneration could slow its progression by taking zinc (80 mg), vitamin C (500 mg), vitamin E (400 mg), beta-carotene (15 mg), and copper (2 mg) by 25%. Age related macular degeneration is an eye disease that happens when the macula, the part of the retina that is responsible for central vision, starts to break down.  CONTD… Taking a diet rich in beta carotene reduces the risk of cardiovascular diseases to a significant extent. Beta carotene works with vitamin E to reduce the oxidation of LDL cholesterol, thus lowering the risk of atherosclerosis and coronary heart disease.  CONTD… Beta carotene strengthens your immune system by activating the thymus gland which is one of the most important sources of immune protection.  The thymus gland enables your immune system to fight off infections and viruses, thus destroying cancerous cells before they can spread  HIGH INTAKE High doses of beta carotene make your skin less sensitive to the sun. Thus, it is particularly beneficial for people with erythropoietic protoporphyria, a rare genetic condition causing painful sun sensitivity as well as liver problems. Moreover, it can boost the effectiveness of sunscreen. Consumption of about 90 to 180 mg of beta carotene can reduce sunburn and provide an SPF of 4. Side Effects Beta-carotene supplements are especially risky for: Pregnant and breast feeding women Skin discoloration (yellowing that eventually goes away) Loose stools Bruising Joint pain Lutein and zeaxanthin are two types of carotenoids ), which are yellow to red pigments found widely in vegetables and other plants. Though lutein is considered a yellow pigment, in high concentrations it appears orange-red. lutein , mesoxanthin and zeaxanthin are found in high concentrations in the macula of the human eye, giving the macula its yellowish color ( macular pigments).  HEALTH BENEFITS Age-related macular degeneration (AMD): Zeaxanthin and lutein supplementation may protect the eyes against the progression of AMD, which sometimes results in blindness. Cataract: A cataract is a clouding of the eye's lens. Zeaxanthin and lutein consumption may slow the formation of cataracts. Uveitis: Uveitis is an inflammation or swelling of the eye's uvea. The uvea is located in the center of the eye, between the sclera and the retina, and is responsible for supplying blood to the retina. Zeaxanthin and lutein may aid in slowing the inflammatory process. Diabetic retinopathy: Diabetic retinopathy is a complication of diabetes that results from damage to blood vessels in the retina. Supplementing with zeaxanthin and lutein may reduce oxidation processes that damage the eyes INTAKE LEVEL Recommended level for eye health : 10 mg/day for lutein and 2 mg/day for zeaxanthin Daily zeaxanthin consumption may protect skin cells from premature aging as well as UVB-induced tumors. Though harmless, a person with fair skin may develop a yellowish coloration of the skin after exceeding the maximum daily recommended level for adults (20 milligrams)  CONTD…  Lycopene is the red carotenoid found predominantly in tomatoes and in a few other fruits and vegetables.  A potent and specific inhibitor of cancer cell proliferation, which is regulated by an elaborated cellular process called “cell cycle.” Lycopene may prevent malignant transformation  The human body is unable to synthesize carotenoids from endogenously produced biochemicals, the body is totally dependent on dietary sourced (exogenous) carotenoids.  In general, tomato fruit and tomato-based food products provide at least 85% of dietary lycopene in humans.  The remaining 15% are usually obtained from watermelon, pink grapefruit, guava, and papaya—all fruits that are dietary sources of lycopene, although at much lower levels than tomatoes  ABSORPTION Once ingested, lycopene appears in plasma, initially in the chylomicrons (microscopic emulsified fat particles found in the blood serum and lymph that result from fat digestion) and VLDL fractions and later in LDL lipoproteins and HDL (high-density lipoproteins. The highest levels are found in LDL. Serum concentrations vary markedly from about 20 to 500 mcg/liter of serum. LYCOPENE  Both are antioxidants BETA-CAROTENE  Both have anti- inflammatory and  Beta-carotene supplements anti-cancer can negatively interact with a properties.. number of medications, including statins, cholesterol-  Both protect against lowering drugs. cognitive decline and  Lycopene has potential complications when combined eye disease with blood thinners, fertility medications, nicotine SIMILARITIES VS  Beta- carotene is a precursor of vitamin A DIFFERENCES while lycopene is not a precursor to anyone. Anthocyanins and anthocyanidins Anthocyanins are a very large group of red-blue plant pigments. Anthocyanins occur in all higher plants, mostly in flowers and fruits but also in leaves, stems, and roots. In these parts they are found predominantly in outer cell layers the colour of anthocyanins depends on the structure, but also on the acidity of the fruit. Many antocyanins are red at acidic conditions and turn blue at less acid conditions. Structure  Occurrence and function In food, the main sources of anthocyanins are berries, such as blackberries, grapes, blueberries etc, and some vegetables, such as egg-plants (aubergine) and avocado. Other sources include oranges, elderberry, olives, red onion, fig, sweet potato, mango and purple corn. The natural production of anthocyanins in nature is estimated to be 109 tonnes/year  POTENTIAL USES Anthocyanins extracted from plants have been used as food additives. Food additive, E163, is one of the commercial additives derived from fruit anthocyanin such as grape skin.  It is a purple food additive for use in producing purple-colored jam, confectionaries, and beverages  Mechanism of Action It causes suppression of reactive species formation, through enzyme inhibition or the sequestration of trace elements involved in the production of free radicals anthocyanins are effective against cytotoxicity, DNA SSB formation (Single-strand DNA- binding protein (SSB) and lipid peroxidation induced