Selenium is a trace mineral that the human body requires in small amounts to function properly. It is obtained through diet and is involved in various bodily processes that support systemic balance.
Understanding Selenium’s Basic Role
Selenium performs its functions primarily by being incorporated into a group of proteins called selenoproteins. Many selenoproteins act as antioxidants, helping to protect cells from damage caused by unstable molecules known as free radicals. Selenium also supports the immune system.
How Selenium Supports Liver Health
Selenium contributes to liver health by enhancing the organ’s antioxidant defenses. Many selenoproteins, such as glutathione peroxidases (GPx), directly neutralize reactive oxygen species (ROS). This action reduces oxidative stress within liver cells, which is a significant factor in the progression of various liver conditions. By mitigating oxidative damage, selenium helps maintain cellular integrity and function in the liver.
The mineral also plays a role in modulating inflammatory responses within the liver. Studies indicate that selenium can reduce the expression of pro-inflammatory genes, such as cyclooxygenase-2 (COX-2) and tumor necrosis factor-alpha (TNF-α). It can also suppress the activation of certain inflammatory pathways, contributing to an anti-inflammatory effect in liver tissue. This modulation helps prevent overreactions that could lead to chronic inflammation and subsequent liver damage.
Selenium further aids the liver’s natural detoxification processes by supporting the reduction of oxidative stress. For instance, in conditions like alcoholic liver disease (ALD), ethanol-induced oxidative damage can deplete the body’s selenium levels. Supplementing selenium can restore GPx activity in liver cells, reduce ROS, and alleviate oxidative stress, inflammation, and lipid peroxidation, which are all factors in ALD progression.
Selenium’s mechanisms can be beneficial in supporting the liver when faced with conditions such as non-alcoholic fatty liver disease (NAFLD) and viral hepatitis. Patients with NAFLD often exhibit lower selenium levels than healthy individuals. Supplementation can help alleviate metabolic disorders in NAFLD by reducing anti-oxidative stress and anti-inflammatory responses. While selenium is not a cure for these conditions, its supportive role through antioxidant and anti-inflammatory actions helps protect liver cells and maintain their function.
Getting Enough Selenium
Obtaining sufficient selenium typically occurs through a balanced diet. Brazil nuts are particularly rich, with just a few nuts providing a substantial amount. Seafood, including yellowfin tuna, sardines, shrimp, cod, halibut, and salmon, also serves as an excellent source. Other common dietary sources include various meats like beef, pork, poultry, and eggs.
Whole grains such as breads, cereals, and brown rice, along with beans, lentils, and other nuts, also contribute to selenium intake. The selenium content in plant foods can vary significantly based on the mineral levels in the soil where they are grown. For adults aged 14 and older, the recommended daily allowance for selenium is approximately 55 micrograms. Pregnant individuals typically need around 60 micrograms per day, while those who are lactating require about 70 micrograms daily.
Most people in developed countries get enough selenium from their diet. Therefore, routine supplementation is not advised unless a deficiency is identified. If considering a selenium supplement, it is advisable to do so cautiously and ideally under the guidance of a healthcare professional to ensure appropriate dosage and avoid excessive intake.
Safety and Usage Guidelines
While selenium is beneficial, both deficiency and excessive intake can have adverse effects. Selenium deficiency can lead to symptoms such as infertility, muscle weakness, fatigue, and hair loss. Severe deficiency has been linked to conditions like Keshan disease, a cardiomyopathy affecting the heart muscle, and Kashin-Beck disease, which impacts joints and bones. Myxedematous endemic cretinism, characterized by intellectual disability, is also associated with insufficient selenium.
Conversely, consuming too much selenium can result in toxicity, a condition known as selenosis. Symptoms of selenosis include a garlic-like odor on the breath, a metallic taste in the mouth, hair loss, and brittle nails. Other signs can involve skin rashes, nausea, diarrhea, extreme tiredness, irritability, and even neurological issues. The Tolerable Upper Intake Level (UL) for selenium in adults is 400 micrograms per day, and exceeding this amount consistently can lead to these toxic effects.
Brazil nuts, due to their high selenium content, can easily contribute to excessive intake. Given the narrow range between beneficial and potentially harmful levels, it is highly advisable to consult with a healthcare professional before starting any selenium supplementation. This consultation can help determine if supplementation is necessary, establish an appropriate dosage, and avoid potential adverse effects or interactions with other medications.