I found a bodybuilding web page, which lists natural ways to increase testosterone. Apparently, zinc is very important. The page is called "ways-to-increase-testosterone-levels-naturally-without-using-steroids.htm" which you could google to find -- I won't post the link because it's also advertising this guy's business, but here is the things he lists (which should be verified as safe before you do any of these, obviously).
14 ways to naturally Increase your testosterone
1. Get more Zinc
Zinc is very important for the production of natural testosterone because Zinc prevents testosterone from being converted into estrogen (the female hormone) by making the enzyme aromatase not work (see #3 below).
Zinc itself turns estrogen into testosterone and helps produce healthier sperm and higher sperm counts so, low levels of zinc can cause low testosterone levels.
Foods high in Zinc include oysters, beef, liver, crab, seafood, poultry, nuts and seeds, salmon, brown rice, cheese, pine nuts, beans, turkey, milk, yogurt, and cottage cheese or supplement with 50-to-100mg Zinc daily.
2. Eat healthy fats
Research has shown that men who ate diets rich in healthy fats like monounsaturated fats & Omega-3 fats had the highest testosterone levels.
Add more nuts & seeds, fatty fish like salmon & tuna, avocados, olives, vegetable oils, and natural peanut butter.
A very low-fat diet can actually lead to lowered testosterone levels - your body needs healthy fats in order to produce testosterone. This doesn't mean you should eat a REAL HIGH fat diet - Just make sure at least 20-to-30% of your total daily calories comes from healthy fats.
3. Lose body fat
The more overweight you are or the higher your body fat percentage is = the higher your estrogen levels will be. Body fat contains an enzyme, aromatase, that converts your testosterone into estrogen.
Do fat burning workouts to lower body fat, reduce estrogen and increase testosterone.
Try not to cut too many calories when trying to lose body fat because you don't want your body going into starvation mode and cause your body to stop making testosterone.
Make sure you focus on losing 1-to-3 pounds of fat a week mainly thru fat loss workouts and a basic diet plan
4. Get rid of excess estrogen
To get rid of excess estrogen that makes you fatter & weaker so your body can naturally produce more testosterone...
* Eat more RAW cruciferous vegetables (broccoli, cabbage, cauliflower, etc.). Cruciferous vegetables contain a chemical called diindolylmethane (or DIM) that helps you rid excess estrogen from your body. You can supplement with DIM to flush out excess estrogen.
* Eat more fiber to naturally cleanse your body and flush out toxins that cause you to have excess estrogen (like the xenoestrogens from #5 below).
* You can also supplement with Red grape skin extract (resveratrol) to help your liver remove excess estrogen.
5. Try to avoid Xenoestrogens
Xenoestrogens are manmade estrogens found in things like pesticides, artificial growth hormones & steroids, air fresheners and plastic containers and these xenoestrogens will increase your levels of the female hormone estrogen while lowering testosterone.
* Eat more organic fruits & vegetables that are free of pesticides. If you buy your fruits & vegetables at a grocery store, make sure you wash them to lower your chances of consuming any xenoestrogens.
* Eat more naturally raised meats without artificial growth hormones and steroids.
* Use glass products to store food & water. Plastic products tend to produce xenoestrogens that'll get into your water & food especially when heated. Even some canned foods contain plastic coatings that contain xenoestrogens.
* Don't use any perfumes, colognes, or air fresheners that have parabens listed as one of the ingredients. Parabens are xenoestrogens.
Note: It's hard to completely avoid all xenoestrogens but if you follow the other tips on this page (especially tips #3 & #4), you can still naturally increase your testosterone while getting rid of excess estrogen without having to worry so much about trying to avoid xenoestrogens.
Note: Since most xenoestrogens accumulate in your body fat - your best defense against xenoestrogens is to lose body fat.
6. Get at least 6-to-8 hours of Sleep every night
A study showed that men who got little sleep had way lower testosterone levels than men who got 6-to-8 hours of sleep and... According to a University of North Carolina study... Your testosterone levels can drop down by as much as 40 PERCENT when you don't get enough sleep.
Testosterone levels tend to be 30% higher in the morning than in the evening and this is why you may be more horny in the mornings.
A loss of morning erections or loss of sexual desire in the morning can be a sign that testosterone is declining, so get 6-to-8 hours of sleep every night because while you're sleeping your body produces the most testosterone and the better you sleep the more testosterone your body will produce while you sleep.
7. Stress Less
When you get stressed out - your body releases a "stress" hormone called cortisol that shuts down testosterone production. Research led by Population Council endocrinologist Matthew Hardy found that stress hormones like cortisol overpower the enzymes responsible for ensuring that cells in the testes produce testosterone.
Cortisol makes you gain belly fat and you already know from #3 above that the fatter you are = you'll have more estrogen and less testosterone.
Stop worrying about the little things, avoid overtraining, and control your temper to reduce your stress levels and increase Testosterone.
8. Take 1000-to-1500mg of Vitamin C per day
Now if you have a hard time avoiding stress - you want to start taking 1000-to-1500mg of Vitamin C per day because...
1. Vitamin C has been shown to lower cortisol levels allowing your body to make more Testosterone and like Zinc.
2. Vitamin C reduces the armostase enzyme that converts your Testosterone into Estrogen.
9. Workout like a man
You can force your body to produce a lot of testosterone with exercise.
* Do Compound exercises that train large muscle groups: Power Cleans, Squats, Bench presses, Deadlifts, Chin-ups, Dips, and Military presses and you can still do isolation exercises like triceps extensions, bicep curls or chest flyes for definition but if trying to boost your Testosterone and build more muscle quickly - stick with compound exercises.
* According to a Swedish study, to get the biggest boost in testosterone when you do your compound exercises use heavy weights that will allow you to only do about 3-to-5 reps per set. Do about 5-to-8 sets of each compound exercise.
* Limit your workout time on those compound exercises to 1-to-2 hours so just do only 1-to-2 compound exercises followed by a few optional isolation exercises twice a week (Mon. & Thur. for example) and as for burning fat...
* Avoid 'sissy cardio' where you walk or run for long periods of time and start doing Manly Cardio workouts like Hill sprints and intervals 3-to-4 times a week and limit your long duration sissy cardio workouts to only 2 times a week.
* Rest harder than you workout. Overtraining leads to more cortisol and lowers testosterone. Try to get 8+ hours of sleep to allow your body to recuperate and produce more testosterone after you workout.
10. Get Sexually Stimulated as much as possible
If you're not getting sexual stimulated or sexual aroused very much right now (especially if you're over 40), you can dramatically boost your testosterone levels by getting sexually stimulated more often.
Start doing almost anything you can to get an erection. German scientists found that simply having an erection causes your levels of circulating testosterone to rise significantly.
Not getting sexual stimulated or aroused for long periods of time can actually decrease your testosterone levels so if you find it hard to get sexually stimulated. You can do all the other 12 things on this page to increase your testosterone which will increase your sex drive or libido making you get sexually stimulated much easier.
You can take a supplement like Horny Goat Weed to make you get sexually stimulated more easier to ramp up your testosterone levels.
11. Make sure you're getting enough Vitamin A, B & E
Vitamins A , B & E (with Vitamin C & zinc) are essential in the production of testosterone. Not getting enough A, B, & E Vitamins will lead to lower testosterone levels. If you're eating plenty of fruits & veggies, lean meats and nuts then you shouldn't have to worry too much about supplementing with any extra A, B, & E Vitamins.
12. Don't overheat your testicles
Your testicles need to be 94-to-96 degrees or 2 degrees cooler than your body temperature to function best and produce the most testosterone.
Stop wearing tight underwear, tight pants, taking long HOT baths, or anything else that overheats your testicles. It's best to wear looser clothes like boxers.
Carrying around excess fat also overheats your testicles so look at #3 again for how to burn fat.
13. Don't Drink Alcohol & Don't eat Grapefruit
Even if you had only 2 drinks a day, alcohol makes it hard for your liver to breakdown estrogen making you have more estrogen & less testosterone.
Alcohol decreases zinc levels in your body and grapefruit can make it hard for your liver to breakdown estrogen.
14. Boost Testosterone 40% with D-Aspartate
D-Aspartate is an amino acid that's produced in your pituitary gland and your testicles (or your balls) and it boosts the production of testosterone.
D-Aspartate also increases sperm production . . . men taking 3 grams of D-Aspartate every morning increased their testosterone by 40%.