What is testosterone?
Testosterone is an anabolic steroid hormone that is present in males and also in females, only in a much lower level. Testosterone is the main male sex hormone-androgen. It is important hormone throughout life and insures many different functions. Testosterone is produced mainly by the testes, but also in small dosages in adrenal glands. Production of testosterone is controlled by the hypothalamus-pituitary system in the brain.
In fetus, testosterone takes part in development of male genitalia. Lack of testosterone during fetal development can lead to development of female genitalia or ambiguous genitalia. During puberty, testosterone levels rise significantly and ensure development of secondary sex characteristics, such as growth of body and facial hair, increase in penis and testicular size. During adulthood, testosterone is responsible for sex drive, fertility and also maintenance of heart wellness, muscle and bone strength amongst other functions .
Causes of low testosterone
Normally, testosterone levels tend to decrease with age and it is a normal part of aging. In some cases, testosterone levels are low even before birth or do not reach sufficient levels during puberty. Mainly, the causes for low levels of testosterone can be divided in primary and secondary. Primary hypogonadism means that testosterone is not produced at all or is in significantly lower levels, due to testis related problems, such as:
- Mumps orchitis
- Undescended testes
- Klinefelter syndrome
- Physical injury to testes
Secondary hypogonadism means that testosterone production is impaired due to lack of brain stimulation to testes. This can be caused by:
- Pituitary disorders
- Inflammatory diseases
- Kidney disease 
Symptoms of low testosterone level
During adulthood, low testosterone levels can cause a variety of symptoms. These symptoms are not specific, and can be caused by another condition. Most commonly seen symptoms include:
- Decreased sex drive
- Low energy, fatigue
- Weight gain
- Heart problems, increased cholesterol levels
- Anxiety, moodiness
- Trouble focusing
- Low self-esteem
- Loss of body hair
- Thinner bones 
How to boost testosterone from Foods?
There are still discussions amongst scientists, what low testosterone levels mean. Currently, American Endocrine Society states that low levels signify amount of less than 300ng/dL (with normal range being up to 1050 ng/dL) and presence of symptoms. National HRT suggests the use of several different synthetic testosterone replacement options, but several home remedies, including food can be used prior.
Testosterone Boosting Foods List
Vitamin D is a very important nutrient that helps the body to absorb calcium. It is important for maintaining healthy immune system, maintenance of bone strength and other functions. Vitamin D also has a role in testosterone production.
Studies have found that low vitamin D levels are linked with low testosterone levels. It has also been found that correcting low vitamin D levels helps to increase testosterone levels. Vitamin D is usually produced by skin cells after exposure to sun. It can also be taken daily as a supplement. It is also found in fatty fish, like salmon and tuna, certain mushrooms, egg yolks and beef liver. Many manufactured foods like milk and cereals also contain extra vitamin D .
Zinc is a very essential mineral during puberty. It helps to keep hormone levels in normal levels, including testosterone. Low levels of testosterone are often seen in men who have low zinc levels, therefore it can help to increase it.
A very good source of Zinc are Oysters. Also, other types of seafood, like shellfish are rich in zinc. It is also found in beef, lamb, seeds and grains and vegetables. Cocoa and chocolate are also good sources of the mineral .
One of the reasons for low levels of testosterone can be that the body lacks fats. Monounsaturated and saturated fats take part in hormone production, therefore are essential in maintaining healthy levels of testosterone.
Foods that contain these fats include red meat, whole dairy products, nuts and seeds, avocados and olive oil .
Carbohydrates play a very important role in regulating normal body functions and hormone levels. Increase in blood glucose levels ensures the proper function of gonadotropin releasing hormones from the brain, which is essential for testosterone production in testicles. Still, not all types of carbohydrates are good. Gluten-rich product increase production of prolactin, which significantly lowers testosterone levels.
To increase testosterone, it is best to use carbohydrates from vegetables, like potatoes, white rice, fruits and fruit juices, as well as cane sugar .
- What is testosterone: http://www.livescience.com/38963-testosterone.html
- Causes of low testosterone: http://www.healthline.com/health/what-is-testosterone#LowTlevels2
- Symptoms: http://www.webmd.com/men/features/low-testosterone-explained-how-do-you-know-when-levels-are-too-low#1
- Vitamin D: http://www.health.com/health/gallery/0,,20504538,00.html#beef-liver-0
- Boosting foods: http://www.healthline.com/health-slideshow/testosterone-boosting-food#promoSlide
- Fats: http://www.livestrong.com/article/308751-how-do-i-reduce-male-testosterone/
- Carbohydrates: https://www.anabolicmen.com/carbohydrates-testosterone/