Which of the Following Minerals Can Function as an Antioxidant?

Vitamins and Minerals as Antioxidants

What Are Antioxidants, and Why Do We Need Them?

Recall from Unit of measurement one that atoms are composed of a nucleus, which contains neutrons and protons, and electrons, which orbit the nucleus. Atoms are most stable when they have an fifty-fifty number of electrons, and then that they tin can orbit the nucleus in pairs.

An atom or group of atoms with an unpaired electron is called a . Free radicals are inherently unstable and highly reactive. They steal electrons from other molecules in order to stabilize themselves, but in doing so, they create additional gratis radicals. This electron-grabbing is called and tin can gear up a chain reaction, creating new complimentary radicals and damaging important molecules along the way, similar to how one falling domino can bring downwards countless more.

Effigy 8.12. A complimentary radical is a molecule with an unpaired electron. It can steal electrons from a stable molecule, creating a new free radical and initiating a chain reaction.

are molecules that tin donate an electron to stabilize and neutralize free radicals. Like a domino that refuses to fall, an antioxidant can stop the free radical chain reaction in its tracks. In donating an electron, the antioxidant itself becomes a free radical. However, antioxidants are special in that they are non very reactive themselves and have processes for quick stabilization.

Figure eight.13. Antioxidants stabilize free radicals past altruistic electrons, preventing the concatenation reaction that can create more free radicals.

Some antioxidants are produced by the body, and some are consumed in the diet. Examples of dietary antioxidants include vitamins C and E, the mineral selenium, and phytochemicals, such equally beta-carotene. We'll focus on vitamins C and E and selenium on this page, and we'll discuss beta-carotene on the next folio.

Gratuitous radicals are a natural byproduct of metabolic reactions and of exercise, and it'southward normal to have depression levels of gratis radicals in the trunk. In fact, complimentary radicals play a role in normal functioning of the body, including the ability to fight off pathogens and to send signals from ane prison cell to another. And with plenty antioxidants present, costless radicals can exist kept in cheque so that they aren't dangerous.¹

However, too many free radicals and not plenty protection from antioxidants creates a situation chosen . Free radical-induced harm, when left unrepaired, destroys lipids, proteins, RNA, and DNA, and can contribute to disease. Oxidative stress has been implicated as a contributing factor to cancer, cardiovascular affliction, arthritis, diabetes, kidney disease, Alzheimer's disease, Parkinson's disease, and eye diseases such as cataracts.²

Substances and energy sources from the surround can add together to or accelerate the production of free radicals within the torso. Exposure to UV radiations (east.g., from sunlight), air pollution, tobacco smoke, heavy metals, ionizing radiation, asbestos, and other toxic chemicals increase the amount of costless radicals in the body. They do so past being gratuitous radicals themselves or past adding energy that provokes electrons to move between atoms. Excessive exposure to ecology sources of costless radicals can contribute to disease by overwhelming the free radical detoxifying systems and those processes involved in repairing oxidative harm.

Oxidative stress is associated with the development of chronic diseases, and eating a diet rich in antioxidant-containing foods like fruits, vegetables, and whole grains seems to protect against many of these same diseases. Information technology was thus natural for researchers to hypothesize that taking antioxidants in supplement form might also offer protection from these diseases. All the same, several decades of research investigating this hypothesis take revealed disappointing results. Not only take these studies shown that antioxidant supplements generally aren't beneficial, some have shown that they can cause health risks. For example, high doses of beta-carotene increased the risk of lung cancer in smokers, and high doses of vitamin East increased the adventure of prostate cancer in men. Antioxidant supplements may also interact with other medications, further emphasizing the importance of talking with your doc before taking supplements.^two

Researchers aren't sure why some antioxidant supplements take turned out to be unsafe. It may come dorsum to the fact that free radicals play of import roles in the body, and adding high doses of antioxidant supplements overwhelms the normal rest of free radicals and does more than impairment than skillful. It may too be that the benefits of eating antioxidant-rich foods come not just from the antioxidants merely from the entire bundle of nutrients, like fiber and phytochemicals in the whole foods, a combination that only can't be replicated in a pill. Regardless, you can obtain adequate levels of dietary antioxidants simply by eating a healthy diet.^1,two

Let'due south take a closer look at several of the most important dietary antioxidants: vitamin E, vitamin C, and selenium.

Vitamin E

When nosotros talk near vitamin E, we're actually referring to 8 chemically similar substances, of which blastoff-tocopherol appears to exist the most potent antioxidant. Because vitamin East is fatty-soluble, its antioxidant capacity is especially important to lipids, including those in prison cell membranes and lipoproteins. For example, free radicals can oxidize LDL cholesterol (stealing an electron from information technology), and it is this damaged LDL that lodges in blood vessels and forms the fatty plaques characteristic of atherosclerosis, increasing the risk of center attack, stroke, and other complications of cardiovascular disease.

Later on blastoff-tocopherol interacts with a free radical it is no longer capable of acting as an antioxidant unless it is enzymatically regenerated. Vitamin C helps to regenerate some of the alpha-tocopherol, but the balance is eliminated from the trunk. Therefore, to maintain vitamin E levels, you ingest it as part of your diet.

In addition to its antioxidant functions, vitamin E, mainly every bit alpha-tocopherol, plays a role in the immune system, regulation of gene expression, and cell signaling. It as well enhances the dilation of blood vessels and inhibits blood clot formation.

Nutrient Sources of Vitamin E

Splendid dietary sources of vitamin E include basics, seeds, and vegetable oils, with additional amounts provided by green leafy vegetables and fortified cereals.³

Effigy viii.14. Dietary sources of vitamin E. Source: NIH Role of Dietary Supplements

Surveys of Americans' diets often find that they provide less than the RDA for vitamin E. All the same, these studies may underestimate the amount of vitamin E in the diet because they don't fully account for vegetable oils in the nutrition, every bit these are rich sources of vitamin E. Vitamin E can be destroyed at high temperatures, specially when reheated repeatedly, and so oils used in deep frying are not good sources of the vitamin.

Vitamin East Deficiency and Toxicity

Outright vitamin East deficiency with obvious deficiency symptoms is very rare in good for you people. It well-nigh often occurs in people with an underlying disorder that impairs the digestion and absorption of fat. Symptoms of vitamin Eastward deficiency include nerve and muscle damage, vision issues, and a weakened allowed system.³

Studies have not found any risks of consuming vitamin E in foods. The UL for vitamin E is set up at 1,000 mg for adults, far above the RDA of 15 mg and far higher than could naturally be obtained from nutrient. These amounts are available in supplement grade, however. Equally mentioned, high-dose vitamin Due east supplements were shown to increase the take chances of prostate cancer in men. Other studies have institute that loftier-dose vitamin E supplements are associated with an increased risk of hemorrhage, stroke, and death.

Vitamin C

Vitamin C, also called ascorbic acid, is a h2o-soluble vitamin essential in the nutrition for humans. Interestingly, most other mammals tin readily synthesize vitamin C and don't require it in their diets. Vitamin C'due south power to easily donate electrons makes it a highly effective antioxidant. Since it is water-soluble, information technology acts both inside and outside cells to protect molecules in aqueous environments. Vitamin C also plays a vital role in regenerating vitamin Due east subsequently it has acted as an antioxidant, allowing information technology to be recycled and used again.

Figure 8.fifteen. Afterward vitamin E donates an electron to neutralize a free radical, it can be regenerated by an electron from vitamin C. Vitamin C is and then regenerated by antioxidant enzymes.

In addition to its office as an antioxidant, vitamin C is a required part of several enzymes involved in the synthesis of , a protein important to the strength and construction of muscles, basic, tendons, ligaments, connective tissue, and peel. Vitamin C is also required to synthesize neurotransmitters important for signaling in the brain, some hormones, and amino acids. It as well plays a function in immune office and improves the absorption of dietary iron.

The body's vitamin C status is tightly controlled to maintain steady tissue and plasma concentrations. This ways that if you consume loftier doses of vitamin C, you lot'll absorb less from the intestine and excrete more in urine to preclude excessive concentrations in the body. Vitamin C is not stored in whatever significant amount in the body, but once information technology has reduced a gratis radical, it is very finer regenerated and therefore can exist in the body as a functioning antioxidant for many weeks.

Food Sources of Vitamin C

Fruits and vegetables are great sources of vitamin C. Some of the best sources include bong pepper, citrus, broccoli, strawberries, Brussels sprouts, and cantaloupe.⁴

Figure 8.16. Dietary sources of vitamin C. Source: NIH Office of Dietary Supplements

Because vitamin C is water-soluble, it leaches away from foods considerably during cooking, freezing, thawing, and canning. Up to l% of vitamin C can exist boiled away. Therefore, eating fruits and vegetables raw or lightly steamed maximizes the vitamin C value of these foods.

Vitamin C Deficiency and Toxicity

The classic status caused by vitamin C deficiency is . The signs and symptoms of scurvy include pare disorders, bleeding gums, joint pain, and weakness—all of which may be related to vitamin C'due south role in collagen synthesis. Additional symptoms of scurvy include abnormally-thickened pare, fatigue, low, iron deficiency anemia, and increased susceptibility to infections.

In the past, scurvy was mutual among sailors on long bounding main voyages, whose diets were completely lacking in fruits and vegetables for many months. In the mid-1700s, British Navy surgeon Sir James Lind's experiments revealed that citrus fruits and juices could forbid scurvy in sailors. British sailors were oft referred to as "limeys," equally they carried sacks of limes onto ships to prevent scurvy. It was not until 1932 that scientists showed that vitamin C was the essential nutrient involved in this cure.

Effigy 8.17. This drawing of a crewman with scurvy, from the 1929 edition of "Kranken-Physiognomik" past von K. H. Baumgärtner, shows mutual effects of the disease, including sunken eyes and skin lesions.

Scurvy is prevented by even a low intake of fruits and vegetables, and it takes at least a calendar month of consuming very little or no vitamin C for scurvy symptoms to develop. Thus, scurvy is rare in developed countries today. Diet surveys prove that most Americans encounter the RDA for vitamin C. When vitamin C deficiency occurs today, it is in people who consume very express food variety, such as those with mental illness, people who corruption alcohol or drugs, people on very restrictive diets, and impoverished people with limited fruit and vegetable access. People who smoke besides require more vitamin C to counter the free radicals generated by smoking.

The take chances of vitamin C toxicity from foods is essentially nonexistent, because the trunk can adjust intestinal absorption and urinary excretion to maintain a salubrious vitamin C level. However, high doses of vitamin C from supplements have been reported to cause numerous issues, including gastrointestinal upset and diarrhea. To prevent these discomforts, the UL for vitamin C is set at ii,000 milligrams per day for adults, more than 20 times the RDA.

At very high doses in combination with iron, vitamin C has sometimes been found to increase oxidative stress, reaffirming that getting your antioxidants from foods is better than getting them from supplements. There is also some testify that taking vitamin C supplements at high doses increases the likelihood of developing kidney stones; notwithstanding, this effect is almost oft observed in people that already have multiple adventure factors for kidney stones.

Tin Vitamin C Supplements Prevent the Common Cold?

Many people believe that taking a vitamin C supplement tin prevent the common cold or decrease its symptoms. This idea was popularized past Linus Pauling in the 1970s, and it's continuously promoted today in the grade of over-the-counter supplements such as Emergen-C and Airborne. These typically contain doses in the range of chiliad mg of vitamin C, far higher than normal levels of vitamin C in the nutrition and enough to reach the UL of 2000 mg if a person takes two doses per 24-hour interval.

Do these high-dose vitamin C supplements practice anything to prevent or treat the misery of the common common cold? A systematic review and meta-assay published in 2013 past the Cochrane Collaboration summarized the results of 29 studies conducted on this question. The review ended that for about people, these supplements don't prevent the common cold simply can reduce the duration of symptoms past 8% in adults and fourteen% in children—amounting to a 24-hour interval or two of relief—but only if they're taken consistently every solar day and before cold symptoms brainstorm. If taken later on the onset of symptoms, a vitamin C supplement does not seem to reduce the duration or severity of symptoms. Some research shows that vitamin C supplements may be more effective in cold prevention in athletes and those in extreme physical weather condition, such as marathon runners, endurance skiers, and soldiers.^v

Selenium

Selenium is an essential trace mineral. Information technology is part of the structure of at least 25 proteins in the body, with functions in reproduction, thyroid hormone metabolism, Dna synthesis, and antioxidant and allowed protection.⁶ As part of antioxidant enzymes, selenium helps to regenerate other antioxidants, including vitamin C. These enzymes also protect lipids from gratuitous radicals, and, in doing and then, spare vitamin Due east. This illustrates how antioxidants piece of work together to protect the body confronting free radical-induced damage.

Food Sources of Selenium

Organ meats, musculus meats, and seafood take the highest selenium content. Grains and some nuts contain selenium when grown in selenium-containing soils. The selenium content of the soils used to grow brute feed can as well affect the selenium content of animal products.

Figure 8.eighteen. Dietary sources of selenium. Source: NIH Office of Dietary Supplements

Selenium Deficiency and Toxicity

Selenium deficiency is very rare in the Us and other developed countries. Worldwide, people with a primarily vegetarian diet in areas with low soil selenium levels, including parts of China and Europe, may be at take chances for selenium deficiency.⁶

Chronic exposure to foods grown in soils containing high levels of selenium (in a higher place the UL of 400 micrograms per day) can crusade breakable hair and nails, gastrointestinal discomfort, pare rashes, halitosis, fatigue, and irritability. Brazil nuts incorporate very high levels of selenium, and then if eaten regularly could cause selenium toxicity. Selenium at doses several one thousand times the RDA can cause astute toxicity, and when ingested in gram quantities, tin can exist fatal.

Attributions:

• Zimmerman, Grand., & Snowfall, B. Nutrients Important as Antioxidants. In An Introduction to Nutrition (v. one.0). https://2012books.lardbucket.org/books/an-introduction-to-diet/index.html, CC BY-NC-SA 3.0

References:

• ^aneAdcock, J. (2018, January 10). What are antioxidants? And are they truly good for us? The Conversation. https://theconversation.com/what-are-antioxidants-and-are-they-truly-skilful-for-us-86062
• ²National Centre for Complementary and Integrative Health. (n.d.). Antioxidants: In Depth. Retrieved Apr 2, 2020, from https://www.nccih.nih.gov/health/antioxidants-in-depth
• ³National Institutes of Health Office of Dietary Supplements. (n.d.). Vitamin E – Wellness Professional Fact Sheet. Retrieved April ii, 2020, from https://ods.od.nih.gov/factsheets/VitaminE-HealthProfessional/
• ⁴National Institutes of Health Office of Dietary Supplements. (due north.d.). Vitamin C – Health Professional Fact Sheet. Retrieved Apr two, 2020, from https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/
• ⁵Hemila, H., & Chalker, E. (2013). Vitamin C for preventing and treating the common cold. Cochrane Database of Systematic Reviews, CD000980. https://www.ncbi.nlm.nih.gov/pubmed/23440782
• ⁶National Institutes of Health Office of Dietary Supplements. (n.d.). Selenium- Health Professional Fact Sheet. Retrieved April 2, 2020, from https://ods.od.nih.gov/factsheets/Selenium-HealthProfessional/

Image Credits:

• Effigy viii.12. "Free radical concatenation reaction" by Jacqui Adcock is licensed under CC BY-NC-ND 4.0
• Figure viii.thirteen. "Antioxidant action" by Jacqui Adcock is licensed nether CC Past-NC-ND 4.0
• Figure viii.xiv. "Nutrient sources of Vitamin Due east" by Alice Callahan is licensed under CC By four.0, with images from summit to bottom by Alice Callahan, CC Past 4.0; and Remi Yuan, Annie Spratt, and engin akyurt on Unsplash (license information)
• Figure 8.15. "Vitamin E/vitamin C antioxidant cycle" by Alice Callahan is licensed under CC By 4.0
• Figure eight.16. "Food sources of Vitamin C" past Alice Callahan is licensed under CC BY 4.0, with images from top to bottom by Bruna Branco, Irene Kredenets, Kyaw Tun, and Forest Diver on Unsplash (license information)
• Figure 8.17. "38 twelvemonth old man suffering from scurvy" by von Thousand. H. Baumgärtner, Welcomme Library is licensed under CC Past 4.0
• "Emergen-C supplement photo" by Mike Mozart is licensed under CC Past 2.0
• Figure viii.18. "Nutrient sources of selenium" by Alice Callahan is licensed under CC BY 4.0, with images from top to bottom by sunorwind, Сергей Орловский, Cake Tuxedo on Unsplash (license information), and "par cooked brown rice" by jules is licensed nether CC BY-NC 2.0

moultonuporn1938.blogspot.com

Source: https://openoregon.pressbooks.pub/nutritionscience/chapter/8e-antioxidant-vitamins-minerals/

Share this post