Glossary

What Is Sulforaphane? Sulforaphane is a mustard oil compound found in broccoli and cauliflower. It protects plants against herbivores and, due to its pungent smell and taste, also acts as a deterrent to humans. Numerous mechanistic studies using cell cultures and animal models have demonstrated the antioxidant, anti-carcinogenic, and anti-inflammatory properties of sulforaphane. However, because only a limited number of clinical studies have been conducted in humans, direct evidence of its effects in people is still lacking. Nevertheless, sulforaphane is widely regarded as a promising dietary supplement for reducing the risk of chronic diseases. Where Does Sulforaphane Naturally Occur? Sulforaphane is a mustard oil compound produced by certain plants to defend themselves against herbivores. The plant stores sulforaphane safely in an inactive form within its tissues, ensuring that it is released in its active and aggressive form only when the plant is damaged by predators. In intact cells, it is present as an inactive glucosinolate bound to a sugar molecule.The enzyme myrosinase separates sulforaphane from the sugar, allowing it to carry out its protective function against invading organisms. This enzyme is stored in a different compartment of the plant cell. When the plant tissue is damaged, the glucosinolate and myrosinase come into contact as intended. The enzyme releases sulforaphane, which then acts as a mustard oil compound to defend the plant against attackers.Plants cleverly store sulforaphane in its sugar-bound form within cellular compartments. For humans, this means that the bioavailability of sulforaphane from cruciferous vegetables depends greatly on how they are prepared. Sulforaphane is biologically active only after it has been released from its sugar molecule. Therefore, the enzyme myrosinase must be given sufficient time to act before broccoli, cauliflower, or radish are consumed. Simply cooking the vegetables to break down their cell walls is not an ideal solution because heat rapidly inactivates myrosinase.To improve sulforaphane absorption, vegetables can be finely chopped and left to rest before cooking. Alternatively, broccoli sprouts—which contain much higher concentrations of sulforaphane—can be consumed. Per 100 g of dry weight, broccoli contains approximately 40–170 mg of sulforaphane, whereas broccoli sprouts contain more than 1,000 mg, roughly ten times as much. Dietary supplements provide a convenient way to consume sulforaphane in standardized doses. What Is the Primary Function of Sulforaphane in the Body? Sulforaphane supports the body's antioxidant defense system. Many antioxidant compounds, such as vitamin C and vitamin E, act as direct free radical scavengers by neutralizing reactive oxygen species (ROS). Sulforaphane, however, works differently: it activates endogenous antioxidant systems, including glutathione, which subsequently neutralize ROS. For this reason, experts describe sulforaphane as an indirect antioxidant. Glutathione not only functions as an antioxidant but also plays an important role in detoxification by supporting the transformation of harmful substances within the body, thereby facilitating their elimination through the kidneys. Sulforaphane therefore contributes to the removal of unwanted and potentially harmful compounds not only by activating glutathione but also by stimulating the activity of the proteasome. The proteasome serves as the cell's waste disposal system. It breaks down proteins that are damaged, misfolded, or no longer functional. Longevity researchers believe that the accumulation of such dysfunctional cellular waste contributes to the aging process. The build-up of damaged or misfolded proteins is considered a hallmark of cellular aging and is associated with increased inflammation and a higher risk of chronic diseases. By activating the proteasome, sulforaphane influences these processes. In addition, studies using cell cultures and rodents have shown that sulforaphane activates sirtuins, a family of genes involved in the regulation of longevity. What Are the Benefits of Sulforaphane Supplementation? In several cell culture and animal studies, sulforaphane has demonstrated anti-carcinogenic properties. For example, it inhibited the growth of breast cancer cells, which researchers attributed to its ability to disrupt microtubules that cancer cells require for proliferation. Epidemiological studies have associated diets rich in cruciferous vegetables with a reduced risk of prostate cancer. Sulforaphane has been proposed as one of the mechanistic explanations for this observation. Both mechanistic and clinical studies in humans have shown that sulforaphane reduces the activity of histone deacetylases, enzymes that play an important role in the growth of prostate cancer cells. Inflammation and oxidative stress contribute to the development of arterial calcification, commonly known as atherosclerosis. Sulforaphane may help counteract these risk factors for cardiovascular diseases such as stroke and heart attack. Several studies have demonstrated potential benefits of sulforaphane with regard to antioxidant capacity and inflammatory markers. A meta-analysis in rodents confirmed that sulforaphane can reduce body weight, cholesterol, and triglyceride levels. Additional studies investigating sulforaphane in mouse models of hypertension and diabetes further support the hypothesis that this compound may help prevent cardiovascular disease. The accumulation of dysfunctional or misfolded proteins has been linked to various chronic diseases whose incidence increases with age. Sulforaphane activates the proteasome and promotes the breakdown of this cellular waste. It is therefore hypothesized to contribute to a longer healthspan and potentially increased longevity. However, findings from cell culture and animal studies are not sufficient to demonstrate comparable effects in humans. Accordingly, the authors of one comprehensive review concluded that "further intervention studies are required (...) to reach more robust conclusions." Dietary supplements provide doses equivalent to consuming approximately 500–1,000 g of broccoli or several grams of freshly harvested broccoli sprouts. Because the amount of biologically active sulforaphane obtained from cruciferous vegetables is highly variable, supplementation represents an efficient and standardized method of intake. References Further information and scientific studies on the active ingredient sulforaphane can be found here. Evaporative Light-Scattering Analysis of Sulforaphane in Broccoli Samples: Quality of Broccoli Products Regarding Sulforaphane Contentswww.pubmed.ncbi.nlm.nih.gov/16569031 Sulforaphane Augments Glutathione and Influences Brain Metabolites in Human Subjects: A Clinical Pilot Studywww.ncbi.nlm.nih.gov/pmc/articles/PMC5981770 Antioxidant Functions of Sulforaphane: A Potent Inducer of Phase II Detoxification Enzymeswww.sciencedirect.com/science/article/pii/S0278691599000824 Sulforaphane Protects Against Oxidative Stress-Induced Apoptosis via Activating SIRT1 in Mouse Osteoarthritiswww.pubmed.ncbi.nlm.nih.gov/34184072 Sulforaphane Exhibits Potent Renoprotective Effects in Preclinical Models of Kidney Diseases: A Systematic Review and Meta-Analysiswww.pubmed.ncbi.nlm.nih.gov/37023957 Accumulation of Sulforaphane and Alliin in Human Prostate Tissuewww.pubmed.ncbi.nlm.nih.gov/36014767 The Role of Histone Deacetylases in Prostate Cancerwww.ncbi.nlm.nih.gov/pmc/articles/PMC2683066 Sulforaphane Protects Against Cardiovascular Disease via Nrf2 Activationwww.ncbi.nlm.nih.gov/pmc/articles/PMC4637098 Clinical and Molecular Evidence of the Consumption of Broccoli, Glucoraphanin and Sulforaphane in Humanswww.ncbi.nlm.nih.gov/pmc/articles/PMC4637098

What Is Zinc? Zinc is a mineral and essential trace element that is required for the function of hundreds of enzymes. It is therefore indispensable for sexual health, immune function, brain function, and the body's antioxidant defense. Zinc supplementation is particularly popular for supporting the immune system during the common cold and for stimulating hormone production to promote muscle growth and strength. Where Does Zinc Naturally Occur? Zinc is a mineral found in the Earth's crust and is an essential trace element for the human body. Within the body, it is located primarily in muscles and bones, while less than 1% of the total body zinc is present in the bloodstream. As a result, blood zinc measurements are relatively imprecise, and there is likely a substantial number of people with undetected subclinical zinc deficiency.Zinc is not a rare trace element. It is found in high concentrations in whole grains such as rye, wheat, oats, and rice; seeds including poppy, sesame, pumpkin, flax, and chia; legumes such as lentils and peas; cocoa; liver from wild game and pork; nuts; skeletal muscle meat; and cheese.Most foods contain adequate amounts of zinc. The challenge therefore lies not only in choosing the right foods but also in combining them in a way that maximizes zinc absorption in the small intestine. Plant compounds such as phytic acid and polyphenols, as well as other minerals, can reduce zinc absorption. In contrast, fermentation, sprouting, or consuming fruits and vegetables together with a meal can improve zinc absorption to levels comparable to those achieved from animal-based foods.In dietary supplements, zinc is available in various forms, including zinc oxide, zinc sulfate, zinc acetate, zinc chloride, zinc citrate, and zinc gluconate. However, organic zinc compounds such as zinc histidine are believed to offer the highest bioavailability. What Is the Primary Function of Zinc in the Body? Because zinc is a component of more than 300 enzymes, it ensures the proper functioning of nearly all vital processes in the body. Without zinc, only a small number of enzymes would be capable of catalyzing chemical reactions. It is involved in the metabolism of all three macronutrients: fats, carbohydrates, and proteins. Zinc also plays essential roles in cell growth and immune function, including the regulation of excessive immune responses. As a structural component of zinc finger proteins, which belong to the family of transcription factors, zinc is also involved in the translation of genetic information within the cell nucleus. According to the European Food Safety Authority (EFSA), zinc contributes to the maintenance of normal vision, normal acid-base metabolism, normal cognitive function, normal fertility and reproduction, healthy nails, hair and bones, healthy skin, and the protection of cells from oxidative stress. What Are the Benefits of Zinc Supplementation? According to the German Nutrition Society (DGE), the recommended daily zinc intake ranges from 11–16 mg for men and 7–10 mg for women. The exact recommendation depends, among other factors, on the phytic acid content of the overall diet. Because phytic acid can reduce zinc absorption, individuals consuming diets high in phytic acid should generally aim for the upper end of the recommended intake range. As a rule of thumb, the greater the consumption of whole grains, legumes, and plant-based protein sources, the higher the intake of phytic acid is likely to be. Whether adequate zinc status is consistently achieved cannot always be determined with certainty, partly because of the influence of phytic acid and the limited reliability of individual zinc measurements in the body. An increased risk of inadequate zinc intake exists particularly among people consuming predominantly plant-based diets with a high phytic acid content. Young children, individuals with malabsorption syndromes, and people taking chelating agents, orlistat, laxatives, or proton pump inhibitors may also be at increased risk. According to the German Federal Institute for Risk Assessment (BfR), there is a relevant risk of excessive zinc intake through dietary supplements, although not through conventional foods. This is due to the relatively small margin between the recommended intake and the tolerable upper intake level of 25 mg per day. Consequently, the BfR recommends a maximum daily zinc intake of only 6.5 mg from dietary supplements. For consumers, this means that the phytic acid content of the diet should be taken into account, while zinc supplementation should be approached with caution. In many cases, obtaining zinc primarily from natural food sources is the more prudent strategy. Chronically high zinc intake through supplements may lead to adverse effects. Clinical studies have reported reduced white blood cell counts, impaired immune function, lower hematocrit values, and alterations in lipid metabolism with daily zinc intakes ranging from 50 to 300 mg. In addition, epidemiological studies have associated very high zinc intakes exceeding 75 mg per day with an increased risk of prostate cancer. It is unlikely that zinc supplementation provides additional health benefits in individuals with an adequate zinc status. Positive effects of zinc supplementation have primarily been observed in studies involving insufficient dietary zinc intake, including improvements in acne, depressive symptoms, and blood lipid profiles. One frequently discussed exception is respiratory tract infections, where several meta-analyses have shown that zinc supplementation may shorten the duration of illness. Zinc is essential for normal testicular function and male fertility. It also plays an important role in the body's production of male sex hormones. For this reason, zinc is commonly included in dietary supplements marketed to athletes and in products intended to support muscle growth. What is scientifically well established is that zinc deficiency can impair hormone synthesis and fertility, and that correcting such a deficiency may restore these processes. However, there is currently no convincing evidence that additional zinc supplementation increases male sex hormone levels in individuals who already have an adequate zinc status. The central focus of current scientific research is therefore to determine under which health conditions and chronic diseases difficult-to-detect zinc deficiency may occur—and in which cases targeted zinc supplementation can provide meaningful health benefits. References Further information and scientific studies on the active ingredient zinc can be found here. Zinc: An Essential Micronutrientwww.pubmed.ncbi.nlm.nih.gov/20141096 Bioavailability of Iron, Zinc, and Other Trace Minerals from Vegetarian Dietswww.pubmed.ncbi.nlm.nih.gov/12936958 A Guide to Human Zinc Absorption: General Overview and Recent Advances of In Vitro Intestinal Modelswww.ncbi.nlm.nih.gov/pmc/articles/PMC7146416 Dietary Factors Influencing Zinc Absorptionwww.pubmed.ncbi.nlm.nih.gov/10801947 Revised D-A-CH Reference Values for Zinc Intakewww.pubmed.ncbi.nlm.nih.gov/32380426  

What Is Vitamin K? Vitamin K (quinone) is an essential nutrient and, together with vitamins A, D, and E, belongs to the four fat-soluble vitamins. In the 1920s, unexplained bleeding in cattle and chickens puzzled veterinarians until scientists discovered the role of vitamin K in blood clotting (coagulation). The vitamin was simply named "K" after coagulation. Vitamin K plays an important role in the body as a cofactor for numerous enzymes involved in calcium metabolism. It is commonly supplemented to support cardiovascular health and is often taken together with vitamin D. Where Does Vitamin K Naturally Occur? There are two natural sources of vitamin K: green plants provide vitamin K1, while bacteria produce vitamin K2. Humans obtain vitamin K through their diet, but vitamin K produced by bacteria in the intestinal microbiota is also believed to contribute to the body's supply.Vitamin K1 (phylloquinone) is particularly abundant in photosynthetically active plant tissues such as spinach leaves, lettuce, and parsley. This form accounts for the majority of dietary vitamin K intake but has relatively lower bioavailability.Animal-derived and fermented foods such as liver, muscle meat, cottage cheese, cheese, and eggs contain high concentrations of vitamin K2 (menaquinone). Microorganisms in fermented foods—including the traditional Japanese dish natto as well as cottage cheese and cheese—produce this vitamin themselves. Animal products contain vitamin K2 because animals convert vitamin K1 from plant-based feed into vitamin K2.Vitamin K2 comprises a group of menaquinones with side chains of varying lengths, designated as "MK-n." The most common forms are vitamin K2 MK-7 (with seven isoprene units in its side chain), which is synthesized by bacteria, and MK-4 (with four isoprene units), which is produced in animals through the conversion of plant-derived vitamin K1. Vitamin K2 MK-7 is regarded as the form with the highest bioavailability. There is also the synthetic form, vitamin K3, which is biologically active as well. However, only vitamin K1 and vitamin K2 are approved for use as food additives.Vitamin K is heat-stable, and its absorption can be enhanced when consumed together with dietary fats and oils. Within the body, vitamin K is stored primarily in the liver. Total body stores are relatively small, amounting to approximately 70–100 micrograms. According to the German Nutrition Society (DGE), the recommended daily intake is 70–80 micrograms for men and 60–65 micrograms for women. From the age of 50 onward, the higher intake recommendation applies. What Is the Primary Function of Vitamin K in the Body? According to the European Food Safety Authority (EFSA), vitamin K has been scientifically proven to contribute to normal blood clotting and the maintenance of normal bones. Vitamin K fulfills these functions as a cofactor in the synthesis of proteins involved in blood coagulation and bone formation. These proteins include clotting factors, plasma proteins, and the Gla proteins found in bone-forming osteoblasts, all of which require vitamin K for their production.These observations have led to the hypothesis that vitamin K status may be associated with the risk of arterial calcification and bone loss. In arterial calcification, medically referred to as atherosclerosis, calcium, blood lipids, and other substances form plaques that reduce blood flow, increase blood pressure, and damage blood vessel walls. In osteoporosis, bone minerals such as calcium are progressively lost, resulting in fragile bones and an increased risk of spontaneous fractures.It is therefore well established that adequate vitamin K levels are necessary for the normal function of these physiological processes. Whether specific doses of vitamin K can help prevent the development of atherosclerosis, osteoporosis, or other diseases remains an important area of ongoing scientific research and has not yet been conclusively established. What Are the Benefits of Vitamin K Supplementation? Several cross-sectional studies and randomized controlled trials (RCTs) have shown that vitamin K status or supplementation can improve certain markers of bone health. In particular, low vitamin K intake appeared to be associated with bone loss in female participants. Overall, however, the available evidence is inconsistent, and the level of scientific evidence remains limited. In a meta-analysis of nine randomized controlled trials conducted by a Canadian research group investigating the effects of vitamin K supplementation on arterial calcification and vascular damage, vitamin K increased the activity of an enzyme that helps prevent calcium deposition within blood vessels. However, the authors found no strong evidence that vitamin K supplementation effectively prevents or treats atherosclerosis. Further research is needed to determine whether vitamin K can prevent vascular calcification or improve existing atherosclerotic disease. Like vitamin K, vitamin D is an essential nutrient for bone health. Studies have demonstrated that combining both vitamins in a single supplement enhances their beneficial effects on bone mineral density. Particularly in individuals with a high calcium intake—as is common in Western societies—the combination may help protect against calcium deposits that could develop as a result of excessive vitamin D intake. Because there is currently no reliable biomarker for assessing the body's vitamin K status, nor sufficiently reliable data on the vitamin K content of foods, the German Federal Institute for Risk Assessment (BfR) classifies vitamin K as a Category 2 nutrient. According to the BfR, there is a certain degree of uncertainty regarding vitamin K supply and the potential development of deficiency. If dietary intake is insufficient to meet vitamin K requirements, pharmacy-grade oral supplements providing 50–150 micrograms per day are available. In cases of life-threatening bleeding, up to 10 mg of vitamin K may be administered intravenously. Risk groups for vitamin K deficiency include individuals with eating disorders, inflammatory bowel diseases such as Crohn's disease, patients taking medications that interfere with the vitamin K cycle (including coumarin derivatives and certain antibiotics), as well as newborns and infants. The BfR considers the risk of vitamin K overdose to be moderate and the risk of adverse effects to be low. Toxic reactions such as allergic responses or cardiac arrhythmias have been observed only rarely and primarily after intravenous administration of large doses. For individuals taking anticoagulant medications, the BfR considers a daily vitamin K intake of up to 100 micrograms to be safe. Higher intakes may result in life-threatening complications and should only be taken under medical supervision. References Further information and scientific studies on the active ingredient vitamin K can be found here. The Combination Effect of Vitamin K and Vitamin D on Human Bone Quality: A Meta-Analysis of Randomized Controlled Trialswww.pubmed.ncbi.nlm.nih.gov/32219282 Vitamin K Supplementation for the Prevention of Cardiovascular Disease: Where Is the Evidence? A Systematic Review of Controlled Trialswww.pubmed.ncbi.nlm.nih.gov/32977548 Comparison of Phylloquinone Bioavailability from Food Sources or a Supplement in Human Subjectswww.pubmed.ncbi.nlm.nih.gov/10356087 ,The Role of Menaquinones (Vitamin K2) in Human Healthwww.cambridge.org/core/journals/british-journal-of-nutrition/article/role-of-menaquinones-vitamin-k2-in-human-health/5B9F317B526629D8BA77B6435F1E5509 Vitamin K and Osteoporosis: Myth or Reality?pubmed.ncbi.nlm.nih.gov/28403946

What Is Taurine? In the 19th century, Gmelin and Tiedemann first isolated this amino sulfonic acid from ox bile. Because the Greek word for bull is tauros, they named the substance taurine. Most people know taurine as an ingredient in energy drinks, but it is also an essential endogenous compound that is produced during the metabolism of the amino acid cysteine. Where Does Taurine Naturally Occur? In animal metabolism, taurine is synthesized from the sulfur-containing amino acid cysteine. Foods such as seafood, fish, and meat therefore contain substantial amounts of taurine. Taurine is considered conditionally essential: healthy adults are generally not dependent on dietary intake and typically have 30–70 g of taurine stored in their bodies. However, several medical conditions, including diabetes and cardiovascular disease, are associated with reduced taurine levels.Because cysteine and taurine occur more frequently in animal-derived foods, people following vegetarian or vegan diets generally have lower taurine concentrations in their bodies. Nevertheless, this has not been shown to negatively affect the development of children born to vegan mothers. Taurine is also produced synthetically and is then available as a white powder. What Is the Primary Function of Taurine in the Body? Taurine is involved in numerous metabolic processes. Although it is present in nearly all animal cells, only a few of its biological functions have been clearly defined. One of its best-established roles is the formation of taurocholic acid in the liver, an important component of bile acids that contributes to the digestion and absorption of dietary fats. Taurine is also essential for the development and proper functioning of the brain, nervous system, and neuronal signaling. Taurine deficiency during prenatal and postnatal development can lead to retinal abnormalities and developmental disorders of the brainstem. As an osmoregulator, taurine controls calcium binding to cell membranes as well as the membrane transport of potassium and sodium. Acting as a neuromodulator, it is therefore indispensable for the normal function of the brain, skeletal muscles, musculoskeletal system, and heart muscle. Within the heart, taurine exhibits antiarrhythmic properties and helps maintain a regular heartbeat. It also acts as a potent antioxidant, reducing oxidative stress—presumably by regulating antioxidant enzymes—and supports the body's response to inflammatory processes. What Are the Benefits of Taurine Supplementation? Based on taurine's known physiological functions, researchers are investigating whether supplementation can enhance both physical and cognitive performance. Potential effects on cardiovascular health, eye health, immune function, overall vitality, energy production, and resilience to stress are also major areas of scientific interest. In the past, evidence supporting the benefits of taurine supplementation was limited. The European Food Safety Authority (EFSA) concluded that none of these proposed health effects could be substantiated for taurine supplementation. Nevertheless, many consumers use taurine—alone or in combination with caffeine—to enhance mental alertness and physical performance regardless of the available scientific evidence. More recent meta-analyses, however, provide initial evidence that daily doses of 1–6 g of taurine may improve endurance performance during exercise while reducing DNA damage and blood lactate levels. Even single doses of as little as 0.05 g taken immediately before resistance training have been shown to reduce muscular fatigue and increase antioxidant capacity. Taurine supplementation has also proven beneficial in several disease states that may be associated with increased taurine utilization. For example, taurine has been shown to lower blood pressure in a dose-dependent manner and has demonstrated promising effects in preliminary studies involving individuals with diabetes. Because cases of cardiac arrhythmias, kidney failure, and even deaths have been reported in connection with taurine-containing energy drinks consumed together with alcohol or during strenuous exercise, the German Federal Institute for Risk Assessment (BfR) recommends that children, pregnant women, and breastfeeding women avoid consuming energy drinks. According to the BfR, however, a causal relationship has not yet been established. In clinical studies, participants consumed 10 g of taurine daily for six months or 1 g daily for one year without experiencing significant adverse effects. A daily intake of up to 3 g of taurine is generally considered safe and well tolerated. References Further information and scientific studies on the active ingredient taurine can be found here. The Effects of an Oral Taurine Dose and Supplementation Period on Endurance Exercise Performance in Humans: A Meta-Analysiswww.pubmed.ncbi.nlm.nih.gov/29546641 The Effects of Oral Taurine on Resting Blood Pressure in Humans: A Meta-Analysiswww.pubmed.ncbi.nlm.nih.gov/30006901 The Role of Taurine in Chemotherapy-Induced Cardiotoxicity: A Systematic Review of Non-Clinical Studieswww.pubmed.ncbi.nlm.nih.gov/33275984 Risk Assessment for the Amino Acids Taurine, L-Glutamine and L-Argininewww.pubmed.ncbi.nlm.nih.gov/18325648

What Is Selenium? Selenium is an essential trace element that humans must obtain through their diet. Its discoverer named it after the moon goddess Selene because of its silvery appearance. The United States was the first country to recommend selenium intake in 1989.Selenium follows a U-shaped risk curve: adequate intake is protective, whereas both deficiency and excessive intake increase the risk of conditions such as cancer, diabetes, and cardiovascular disease. Since the body also excretes selenium through the breath, excessive intake or selenium poisoning (selenosis) can cause hair loss, fatigue, and the characteristic "garlic breath." Where Does Selenium Naturally Occur? Selenium is a mineral that occurs naturally in the Earth's crust and has also been detected on the Moon and in meteorites. It enters the food chain because plants absorb it from the soil. However, selenium concentrations in soils vary greatly around the world. Some soils contain almost no selenium, while others produce plants and crops with significant selenium levels.Brazil nuts, seeds, organ meats, and mushrooms are well known for their particularly high selenium content. However, because selenium concentrations vary considerably, obtaining a reliable intake through food alone is difficult. Depending on the region of cultivation and soil composition, a single Brazil nut may provide only a negligible proportion of the daily requirement—or, conversely, potentially toxic amounts of selenium.For this reason, dietary selenium intake depends primarily on where foods are grown and the selenium content of the soil. European soils are generally considered to be low in selenium. Since 1985, Finland has been the only European country to fortify mineral fertilizers with selenium in order to enrich agricultural soils and foods. As a result, the selenium content of Finnish wheat and onions has increased more than tenfold. What Is the Primary Function of Selenium in the Body? The European Food Safety Authority (EFSA) considers it scientifically established that selenium contributes to protection against oxidative stress, the normal function of the immune system, normal thyroid function, and normal spermatogenesis. Adequate selenium status reduces the risk of miscarriage, supports fertility, and promotes healthy thyroid function. Within the thyroid gland, selenium is essential for the activity of the thyroid hormones T3 and T4. As a component of the amino acid selenocysteine, selenium is crucial for the function of several enzymes, including the selenoprotein glutathione peroxidase. In this role, selenium helps maintain oxidative balance between reactive oxygen species (ROS), which are generated through cellular respiration and environmental influences, and the body's antioxidant defense systems, such as glutathione and dietary vitamin C. This function explains many of the symptoms associated with selenium deficiency and is one reason why selenium requirements may increase in conditions such as AIDS, cancer, or hepatitis. Accordingly, individuals with chronic diseases may potentially benefit from an increased selenium intake. What Are the Benefits of Selenium Supplementation? Because the selenium content of foods varies considerably, selenium intake across the population is often inconsistent. Approximately one-third of Europeans consume too little selenium, making selenium supplementation an important consideration. Scientific reviews indicate that adequate selenium intake may reduce the risk of cancer and cardiovascular disease while also exhibiting anti-inflammatory and antiviral properties. Recommended selenium intake is based on the concentration of the selenium transport protein in the blood and its relationship with mortality. Researchers assume that the optimal plasma selenium concentration is reached when the selenium transport protein is fully saturated, which occurs at approximately 110–130 micrograms of selenium per liter. However, studies have shown that mortality risk begins to increase again at plasma concentrations exceeding 150 micrograms per liter. Many people achieve the optimal plasma concentration of 110–130 micrograms per liter by consuming approximately 1 microgram of selenium per kilogram of body weight per day. This corresponds to the intake recommendations of the German Nutrition Society (DGE). The EFSA has established a tolerable upper intake level of 300 micrograms of selenium per day. The relatively narrow range between optimal selenium status and toxicity—even with only modest excess intake—makes careful dosing essential. Accordingly, the German Federal Institute for Risk Assessment (BfR) recommends a maximum daily intake of 45 micrograms from dietary supplements. Observations in livestock and conflicting findings regarding disease prevention also suggest that excessive selenium intake may increase, rather than reduce, disease risk. For example, while adequate selenium status lowers the risk of developing type 2 diabetes, both very low and very high blood selenium concentrations are associated with an increased risk. This U-shaped relationship demonstrates that more is not necessarily better. The case of a 50-year-old individual who developed selenium levels up to fifty times above normal, resulting in visual and memory impairment while attempting to strengthen the immune system, clearly illustrates that with selenium, the dose makes the poison. References Further information and scientific studies on the active ingredient selenium can be found here. Selenium in the Environment, Metabolism and Involvement in Body Functionswww.pubmed.ncbi.nlm.nih.gov/23486107 Selenium and Brain Function: A Poorly Recognized Liaisonwww.pubmed.ncbi.nlm.nih.gov/15210302 Brazil Nut Consumption Improves Selenium Status and Glutathione Peroxidase Activity and Reduces Atherogenic Risk in Obese Womenwww.pubmed.ncbi.nlm.nih.gov/22749175 Selenium Deficiency, Thyroid Hormone Metabolism, and Thyroid Hormone Deiodinaseswww.pubmed.ncbi.nlm.nih.gov/8427195 Scientific Opinion on the Substantiation of Health Claims Related to Selenium and Maintenance of Normal Hair (ID 281), Maintenance of Normal Nails (ID 281), Protection Against Heavy Metals (ID 383), Maintenance of Normal Joints (ID 409), Maintenance of Normal Thyroid Function (ID 410, 1292), Protection of DNA, Proteins and Lipids from Oxidative Damage (ID 410, 1292), and Maintenance of the Normal Function of the Immune System (ID 1750) Pursuant to Article 13(1) of Regulation (EC) No 1924/2006www.efsa.europa.eu/en/efsajournal/pub/1727 Natural Variation of Selenium in Brazil Nuts and Soils from the Amazon Regionwww.pubmed.ncbi.nlm.nih.gov/28923728

What Is Quercetin? Quercetin is a natural pigment belonging to the group of polyphenols and flavonoids. Its name is derived from the Latin word quercus, meaning oak, because the yellow natural dye obtained from the dyer's oak was traditionally used for yellow coloring. In plants, quercetin plays an important role in protecting against oxidative stress, which can also cause cellular damage in humans and is associated with numerous chronic diseases. For this reason, quercetin is being investigated for similar beneficial effects in humans. Where Does Quercetin Naturally Occur? As a flavonoid, quercetin is a plant pigment that is widely distributed throughout the plant kingdom and frequently gives flowers and fruit skins their characteristic color. Accordingly, it is found in particularly high concentrations in unpeeled fruits and vegetables such as onions, blackcurrants, and apples. Due to the high quercetin content of oak wood, the skins of red grapes, and the aging of wine in oak barrels, red wine also contains quercetin.Within plants, flavonoids perform numerous functions. They provide color to attract pollinators, produce an astringent taste that deters herbivores, protect plant cells from oxidative damage caused by ultraviolet radiation, and help prevent colonization of leaves through their antibacterial, antiviral, and antifungal properties. Humans consume quercetin daily through their diet, with an average intake of approximately half a gram per day. What Is the Primary Function of Quercetin in the Body? In the past, it was believed that quercetin and other flavonoids exerted their effects primarily through their antioxidant properties, such as neutralizing reactive oxygen species (ROS). Today, it is known that compounds in this group also promote vasodilation, help prevent blood clot formation, and inhibit the enzymes responsible for generating ROS. Quercetin also regulates inflammation by influencing cellular signaling pathways, inhibiting inflammatory enzymes (cyclooxygenases, COX enzymes), and stimulating certain immune cells. These actions reduce measurable inflammatory mediators such as prostaglandins. The effects of quercetin may therefore help restore physiological balance that has been disrupted by disease or even prevent such imbalances from developing. Indeed, in vivo studies have demonstrated beneficial effects of quercetin on cardiovascular disease, various forms of cancer, and metabolic disorders. Benefits May enhance physical and mental performance May reduce the risk of injuries May promote muscle growth during high-intensity exercise What Are the Benefits of Quercetin Supplementation? Epidemiological studies have demonstrated beneficial associations between flavonoids such as quercetin and a lower risk of cardiovascular disease as well as reduced cardiovascular mortality. A meta-analysis of seven studies involving a total of 587 participants found that quercetin doses exceeding 500 mg per day significantly reduced blood pressure, an important risk factor for cardiovascular disease. Additional systematic reviews of clinical trials confirmed beneficial effects on hypertension and blood lipid profiles when quercetin was taken for more than eight weeks. Even among individuals with normal blood pressure, quercetin supplementation resulted in measurable reductions. Analyses of preclinical studies have shown that quercetin exerts potent effects against viral respiratory infections by reducing viral load, pro-inflammatory mediators, mucus production, and mortality. Because quercetin inhibits a protease essential for the SARS-CoV-2 virus, researchers have also investigated its potential to suppress coronavirus replication. Initial clinical studies in humans suggest that quercetin may shorten recovery time, reduce the length of hospital stays, and decrease inflammatory markers in the blood. Quercetin has also shown promise in the fields of diabetes, Alzheimer's disease, and cancer. In animal models, quercetin improved kidney function, reduced diabetes-associated inflammation in the kidneys, and demonstrated neuroprotective effects in Alzheimer's disease. Preclinical studies provide compelling evidence for the anticancer properties of quercetin. However, in many cases, convincing evidence from human clinical trials is still lacking. In most clinical studies, quercetin was administered at daily doses ranging from 100 mg to 1,000 mg for periods of up to three months. Within this timeframe, it was generally considered safe and well tolerated. Beyond this duration, however, data on long-term safety in humans remain limited. Animal studies suggest that higher doses and prolonged administration may cause liver or kidney toxicity, promote estrogen-dependent cancers, or interfere with the effectiveness of certain medications. References Further information and scientific studies on the active ingredient quercetin can be found here. Quercetin Suppresses Cyclooxygenase-2 Expression and Angiogenesis through Inactivation of P300 Signalingwww.ncbi.nlm.nih.gov/pmc/articles/PMC3152552 Time-Dependent Protective and Harmful Effects of Quercetin on 6-OHDA-Induced Toxicity in Neuronal SH-SY5Y Cellswww.pubmed.ncbi.nlm.nih.gov/18756631 Comparative Mutagenic Effects of Structurally Similar Flavonoids Quercetin and Taxifolin on Tester Strains Salmonella typhimurium TA102 and Escherichia coli WP-2 uvrAwww.pubmed.ncbi.nlm.nih.gov/19326464 Effect of Quercetin Supplementation on Plasma Lipid Profiles, Blood Pressure, and Glucose Levels: A Systematic Review and Meta-Analysiswww.pubmed.ncbi.nlm.nih.gov/31940027 Quercetin and Endurance Exercise Capacity: A Systematic Review and Meta-Analysiswww.pubmed.ncbi.nlm.nih.gov/21606866 The Effects of Quercetin Supplementation on Blood Pressure: Meta-Analysiswww.pubmed.ncbi.nlm.nih.gov/35948195 Quercetin and Ovarian Cancer: An Evaluation Based on a Systematic Reviewwww.pubmed.ncbi.nlm.nih.gov/27904580