A high level of testosterone is closely related to the presence of muscle mass, a lower percentage of body fat and stronger bones.
In addition, an optimal level of testosterone is associated with a good libido, improved cognitive abilities, and of course a higher level of athletic performance.
Unfortunately, nowadays your natural testosterone production is at threat. Here is a short list of things that can affect testosterone levels negatively, ranging from food choices and lifestyle to environmental factors:
Extreme low-calorie diets used for weight loss
Tobacco smoke, even in the case of passive smoking: cigarette smoke contains cadmium, which has been found to reduce testosterone levels.
Alcohol consumption: The body converts alcohol into acetaldehyde, which acts on the testicular cells, reducing the production of testosterone.
Environmental pollution present, for example, in industrial areas, where metal welding, lead or copper smoke is present.
Supplements and Foods That Increase Testosterone
Fortunately, you can improve your testosterone levels by consuming several readily available foods and dietary supplements.
Studies have shown that regular consumption of garlic increases testosterone levels, while reducing the level of cortisol. This is due to a chemical contained in garlic, known as diallyl sulfide. 
Recommended intake: 900 mg per day, preferably divided into several doses throughout the day.
Numerous studies have shown that magnesium has a positive effect on the overall level of testosterone. Unfortunately, most people usually do not get enough magnesium from food. 
Magnesium increases the bioavailability of testosterone. As a result of the natural aging process or as a result of a low-protein diet, the concentration of globulin hormones increases in the body, and these hormones bind to testosterone, making it inaccessible to the body. Magnesium prevents this, thereby preserving the free level of testerone.
However, one study showed that testosterone preferentially binds to magnesium rather than SHBG, thus preserving free testosterone levels and, consequently, its anabolic effects.
In another study, 30 men aged 18-22 years (leading both a sedentary and active lifestyle) received 10 mg / kg of magnesium for four weeks, which led to an increase in free and total testosterone levels.
It is worth noting that the participants of the experiment who intensively performed physical exercises had an even greater increase in the level of testosterone in combination with the addition of magnesium.
Recommended intake: The RDA norm is about 420 mg. per day for an adult male. You can try taking 750 mg. a day for several weeks and see how you feel.
Dietary sources of Magnesium:
Dark green vegetables (spinach, broccoli, cabbage)
Fish (halibut, salmon, mackerel, tuna, pollock)
Nuts (cashews, peanuts, almonds, brazil nuts)
Seeds (pumpkin seeds, sunflower seeds, flax seeds)
Legumes (black beans, edamam, beans)
Low testosterone levels are usually associated with zinc deficiency, since androgen receptors are often altered in people with zinc deficiency. The addition of zinc to the diet has been shown in various studies to increase the level of luteinizing hormone, the pituitary hormone that stimulates the production of testosterone. Studies have also shown that zinc is a strong aromatase inhibitor that can block the conversion of testosterone to estrogen. 
Recommended intake: 30 mg per day
Dietary sources of zinc:
Shellfish (oysters, crabs, lobsters, shrimp)
Dairy products (Swiss cheese, yogurt, milk, cheddar cheese, mozzarella)
Nuts (cashews, almonds, pistachios, pecans, walnuts)
Seeds (pumpkin, squash, pine nuts, chia, flaxseeds)
One of the many functions of vitamin K is to increase the activity level of enzymes that synthesize testosterone. 
It has been proven that the chemical menaquinone-4 (a synonym for vitamin K2) stimulates the production of testosterone through the activation of protein kinase, and also participates in steroidogenesis in the testicles.
Recommended intake: approximately 30-50 mg per day
Dietary sources of vitamin K2:
Hard and soft cheeses
Animal organs (chicken and cow liver)
Fermented foods (sauerkraut, natto, miso, kimchi)
To ensure optimal testosterone levels, consume enough calories for your activity level, with an emphasis on dark green leafy vegetables, protein from animal sources, including internal organs, garlic and zinc / magnesium supplements.
1. Y. Oi, M. Imafuku, C. Shishido, Y. Kominato, S. Nishimura, K. Iwai, Garlic supplementation increases testicular testosterone and decreases plasma corticosterone in rats fed a high protein diet, retrieved from https://pubmed.ncbi.nlm.nih.gov/11481410/
2. Vedat Cinar, Yahya Polat, Abdulkerim Kasim Baltaci, Rasim Mogulkoc, Effects of magnesium supplementation on testosterone levels of athletes and sedentary subjects at rest and after exhaustion, retrieved from https://pubmed.ncbi.nlm.nih.gov/20352370/
3. A. S. Prasad, C. S. Mantzoros, F. W. Beck, J. W. Hess, G. J. Brewer, Zinc status and serum testosterone levels of healthy adults, retrieved from https://pubmed.ncbi.nlm.nih.gov/8875519/
4. Naofumi Takumi, Hitoshi Shirakawa, Yusuke Ohsaki, Asagi Ito, Takaya Watanabe, Puspo E Giriwono, Toshiro Sato, Michio Komai, Dietary vitamin K alleviates the reduction in testosterone production induced by lipopolysaccharide administration in rat testis, retrieved from https://pubmed.ncbi.nlm.nih.gov/21894328/