Selenium is an essential trace element that plays a critical role in various physiological processes within the human body. It is an integral component of selenoproteins, which have antioxidant functions and are involved in processes such as DNA synthesis, thyroid hormone metabolism, and immune system function. Here are key aspects of selenium:
Functions in the Body:
Antioxidant Defense: Selenium is a crucial component of selenoproteins, including glutathione peroxidases and thioredoxin reductases, which help protect cells from oxidative damage. These enzymes participate in the defense against free radicals and reactive oxygen species.
Thyroid Hormone Metabolism: Selenium is involved in the conversion of thyroid hormone thyroxine (T4) to its more active form, triiodothyronine (T3). This process is essential for the regulation of metabolism.
Immune System Support: Selenium plays a role in the proper functioning of the immune system. It helps regulate immune responses and may contribute to the body's defense against infections and illnesses.
Reproduction: Selenium is involved in male and female reproductive health. It is essential for sperm motility and has been linked to male fertility.
Sources of Selenium:
Selenium is found in a variety of foods, and a well-balanced diet usually provides sufficient amounts. Good dietary sources of selenium include:
Seafood: Fish, especially tuna, halibut, and sardines, are rich sources of selenium.
Meat: Beef, pork, chicken, and turkey are good sources of selenium.
Nuts and Seeds: Brazil nuts are particularly high in selenium. Sunflower seeds and wheat germ also provide selenium.
Whole Grains: Brown rice, whole wheat bread, and oats contain selenium.
Dairy Products: Milk and yogurt are sources of selenium.
Eggs: Eggs, particularly the yolk, contain selenium.
Vegetables: Some vegetables, depending on the selenium content of the soil in which they are grown, can contribute to selenium intake. Examples include broccoli and spinach.
Recommended Daily Intake:
The Recommended Dietary Allowance (RDA) for selenium varies based on age, sex, and life stage. As of my knowledge cutoff in January 2022, the RDAs for selenium are as follows:
- Children (1-18 years): 20-40 micrograms per day
- Adults (19 years and older): 55 micrograms per day
- Pregnant women (all ages): 60 micrograms per day
- Lactating women (all ages): 70 micrograms per day