Testosterone production is influenced by a variety of factors including age, training status, amount of body fat stores and one crucial part that most men don’t think about…DIET. Dietary manipulation can also increase testosterone as well. As early as 1979, researchers reported that when men consumed isocaloric diets (i.e., diets containing the same amount of calories) that were low-fat and from vegetarian sources (~25 percent kcals from fat), it resulted in significant decreases in plasma testosterone compared to men receiving moderate-fat diets (~40 percent kcals from fat).
Men have been misled into following low-fat diets/high fiber for cardiovascular health, not realizing that low-fat/high-fiber diets cause reductions in testosterone. For example, reducing dietary fat from a moderate-fat diet (greater than 30 percent calories from fat and low fiber less than 20 g/day) to a low-fat diet (less than 15 percent calories as fat and 25-30g fat per day) significantly reduced total and free testosterone levels and adrenal androgens (androstenedione and DHEA) . Here are a couple of other studies suggesting that low-fat diets are not conducive for testosterone levels.
Fats and Protein Increase Bioavailable Testosterone
A 2007 study in the International Journal of Sports Medicine highlights the importance of having adequate protein and fat in your diet and its effects on testosterone production. In the study, men completed 21 weeks of resistance exercise and were assigned to two groups: one group received nutritional counseling (instructing clients to eat healthier monounsaturated fats) plus strength training and the other group was assigned to strength training alone, with no nutritional help (worked out but ate whatever they wanted). Here are some really interesting findings of the study. At the end of 21 weeks, the average intake of energy (total calories), protein and fat determined the participants’ testosterone levels during the training period. Changes in protein content of diet correlated with the changes in the acute post-exercise concentrations of total and free testosterone after training in the counseling group. Here is what’s really interesting: The degree of muscle mass increased in direct proportion to the level of increase of testosterone. Additionally, researchers from Penn State University conducted a similar study in which they compared the dietary intake of fat and testosterone of 12 men with at least one year of weight training. The researchers found significant correlations between testosterone levels and total fat and testosterone.
SHBG Binds Testosterone!
Remember, when testosterone levels are tested in men, testosterone is only part of the picture. Another part of the equation is sex hormone-binding globulin (SHBG). As the name implies, this hormone binds to testosterone, rendering it not bioavailable to the body. Having high testosterone levels is not going to do you a whole lot of good if you have lot of SHBG binding to it rendering it unavailable. The goal of a testosterone-enhancing diet would be to lower SHBG, allowing more binding of free testosterone to the receptor. SHBG is increased (binds more testosterone) in response to increased fiber intake and decreased (more bioavailable to receptors) with high protein and fat intake. To be more precise, saturated fats have been found to inhibit SHBG activity and increase free testosterone levels. SHBG was found to be significantly decreased after a two-week, high-fat diet (i.e., 100g fat per day) compared to a low-fat diet (i.e. < 20g fat per day).
High Fiber Increases SHBG and Lowers Testosterone
In addition to diets with insufficient fats, which may have deleterious effects on testosterone production, diets that are high in fiber also seem to play a role. For many years, doctors thought that high testosterone causes prostate cancer, but if you have been reading FitnessRx for Men, you would have read testosterone does not cause prostate cancer. Nevertheless, for many years doctors were looking at dietary ways to reduce testosterone to prevent prostate cancer; in their quest to reduce testosterone, two parts of the diet had the greatest impact on reducing testosterone: low-fat/high-fiber diets. It was considered an anti-testosterone diet. When vegetarians with high-fiber diets were compared to Western low-fat diets, vegetarians had lower testosterone levels and when the data was closely analyzed, there was an inverse relationship between dietary fiber intake and T production (the higher the fiber intake, the lower the testosterone production). Others researchers have hypothesized that high intakes of dietary fiber may influence circulation of steroid hormones by altering the absorption of androgen precursors such as cholesterol from the intestines. Vegetarians consuming ~ 50g of fiber a day excrete in stool samples…approximately twice as much estrone, estradiol-17-beta and testosterone compared to omnivores consuming 20g of fiber a day. So, high fiber may be binding testosterone and causing excretion much like cholesterol.
Natural fibers (i.e., brans or oats hulls) as well as purified fibers (e.g., cellulose and lignin) have the ability to bind natural steroid hormones. Studies have suggested lignin has the greatest impact on binding steroid hormones. Each natural fiber bound the following percentage of hormones: lignin (87 percent) followed by wheat and oat bran (45 percent each), corn bran (44 percent) and oats hulls (32 percent). So fiber is needed for health, but there is also too much of a good thing.
Combination of Olive Oil and Saturated Fats Best for Raising Testosterone
Just like proteins have different biological effects on the body slow- (casein) and fast- (whey) digesting proteins, the types of fats differentially regulate testosterone levels as well. Saturated fats and monounsaturated fats have been shown to increase testosterone, whereas polyunsaturated fats seem to lower testosterone levels. Polyunsaturated are divided into two types: omega-6 and omega-3 polyunsaturates. Omega-6 can be found in vegetable oil, corn oil, safflower oil, sunflower oil, peanut oil and sesame oil. Polyunsaturated omega-3 can be found in fish oil, flaxseed oil, canola oil, walnut oil and green leafy vegetables. For many years, people thought that saturated fats were the most important for raising testosterone, but it turns out they were only partly right. Researchers compared the effects of several types of fats on blood pressure, testosterone and cardiovascular parameters. The consumption of the combination oil (mono and saturated fats) was the only group that led to significant increases in testosterone in conjunction with improved markers of cardiovascular disease (reduction in total and LDL cholesterol and a decrease in blood pressure).
Many researchers have suspected that saturated fats increase testosterone, but based on the current study, a combination oil resulted in greater testosterone than a high saturated-fat diet. Coconut oil is a fat consisting of about 90 percent saturated fat. The oil contains predominantly medium-chain triglycerides, with roughly 92 percent saturated fatty acids, 6 percent monounsaturated fatty acids and 2 percent polyunsaturated fatty acids. Interestingly, the blend that contained the higher ratio of monounsaturated to saturated fats resulted in the greatest increase in testosterone than coconut, which is high in saturated fat to monounsaturated fats. This work is in conjunction with studies that have found mono and saturated fats are associated with higher testosterone, yet the study suggests that a higher consumption of olive oil in conjunction with some saturated fats led to greater increases than just saturated fats. It seems that the optimal testosterone-producing diet should have the highest percentage of fats from olive oil (rich in oleic acid), followed by red meat or steak (palmitic acid is a dominant saturated fatty acid in red meat), with a small daily serving a fish oil caps (rich in polyunsaturated fats). Additionally, rats that are fed diets rich in monounsaturated fats had greater 17-beta-dehydrogenase activity (a key enzyme in the testosterone synthesis pathway in the male rat) and plasma androgen concentrations compared to rats fed diets rich in polyunsaturated fats.
Polyunsaturated Fats Are Not Good for Raising Testosterone
Polyunsaturated fats seem to have a negative impact on testosterone levels. For example, men had a 15 percent reduction in serum testosterone concentrations along with a decrease in androstenedione levels (a precursor to testosterone) when subjects were switched from a diet rich in saturated fats to a diet high in polyunsaturated fats. Total dietary fat, saturated fats and monounsaturated fats have been found to increase resting testosterone concentrations in men, whereas diets that are high in polyunsaturated fat are shown to be inversely correlated with T levels. It’s interesting that the use of polyunsaturated fat levels have increased substantially in the American diet; a recent study has reported that testosterone levels are dropping in men. This drop in testosterone during the last 20 years is not related to normal aging; could this drop in testosterone be due to the increase in polyunsaturated fats consumption?
The Fat Threshold
Does that mean you should be eating a bucket a greasy KFC chicken and hamburgers all day long? NO…It seems that there may be a threshold in which consuming an excess of fats does not lead to further increases in testosterone. For example, healthy young men were assigned to a high-fat diet. Subjects were consuming approximately 37 percent fat intake at the start of the study and switched to a diet consisting of 67 percent fat. Interestingly, despite an increase in fat intake there were no increases in testosterone responses. The author hypothesized that there may be a threshold in which further increase in fat do not increase testosterone. Another possible reason for no changes in testosterone was the high-fat diet in the study was rich in n-3 polyunsaturated fatty acids from fish oil and low in cholesterol. As mentioned previously, diets rich in polyunsaturated fats are not conducive to raising testosterone levels. Although saturated fats do raise testosterone, a much safer approach is the famed Mediterranean Diet, which has been shown in several studies to be pro-testosterone. Mediterranean diets emphasize monounsaturated fats (from extra virgin olive oil), some polyunsaturated fats (from nuts), moderate red wine consumption and lots of fruits, whole grains and vegetables. I suspect that the optimal testosterone-producing diet consist of a majority of the fats coming from monounsaturated fats (olive oil) and some saturated fats (occasional steak and red meat). If your main objective is testosterone, you may want to try increasing your saturated fats while decreasing polyunsaturated fats and fiber, as an experiment and see if it helps.
Trans Fats= Testosterone Killer
Trans-fatty acids are formed when liquid vegetable fats are hardened through a process of partial hydrogenation. These trans-fatty acids are partially hydrogenated fats that remain solid at room temperature and are more resistant to oxidation and spoilage. Not surprisingly, such partially hydrogenated oils and hence trans-fatty acids are found in shortenings, some margarines, industrial cooking oils and are commonly found in processed foods such as fast foods, French fries, doughnuts, cookies, dry soup powders and pastries. Trans-fatty acids have been shown to lead to a high LDL, low HDL cholesterol profile and have been shown to increase cardiovascular disease and diabetes. Some studies have shown that trans fats can produce a LDL/HDL cholesterol profile that is even less favorable than for saturated fats. Besides being detrimental to your heart, hydrogenated fats or trans fats can decrease testosterone. For example, male rats fed a diet of hydrogenated fats had a significantly higher incidence of abnormal sperm and lower concentration of testosterone compared to other fats.
A diet rich in monounsaturated fats (olive oil) with moderate amounts of saturated fats (lean steak, lean red meat) with a small amount of omega-3 fatty acids seems to be the healthiest combination of fats for increasing testosterone. Fiber is healthy and is needed for optimal health; however, high intakes of fiber can reduce testosterone by raising SHBG and binding total testosterone, resulting in less free testosterone.
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