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Hormones and Diet
Part Two: Testosterone

By Gary F. Zeolla

Note: This article was revised and expanded and incorporated as a chapter in the book God-given Foods Eating Plan: For Life-long Health, Optimization of Hormones, Improved Athletic Performance.

Part One of this article looked at the relationship of diet to growth hormone. This second part will focus on testosterone. Testosterone (T) is the primary "masculine" hormone. It is the hormone that is primarily responsible for the muscular and sexual differences between males and females. And enhancing testosterone can have a profound beneficial effect on a man's physique, strength, and sex drive and performance.

This is why the lure of steroids is so great. But steroids carry great risks of side effects. But there are ways a man can naturally enhance his own body's production of T. This article will focus on dietary practices that do so.

However, women have testosterone as well, but in much lesser amounts than men. This is why women simply cannot get as muscular as men. But enhancing a woman's testosterone will have some effect on body composition and sex drive; it just won't be as dramatic as with men. And no ladies, unless you use steroids, you will not develop a muscular, man-like physique by enhancing your testosterone. But it will help you develop the shapely, toned figure that you want.

So although this part of this article is mainly directed towards men, it will benefit women as well, just to a lesser degree.

Caution: Some medical authorities believe that elevating testosterone levels will increase the risk of prostrate cancer. This would be due to the elevation of dihydrotestosterone (DHT), a metabolite of testosterone implicated in prostrate cancer. But many factors irrespective of total T levels are involved in the conversion of testosterone to DHT. So increasing testosterone levels will not necessarily elevate the levels of DHT (Faigin, pp. 327-328). But if you have concerns in this regard, consult your doctor. And if you have or are at high risk for prostrate cancer, definitely consult your doctor before making any dietary changes.

Testosterone Background

When testosterone levels are tested in men, the first item usually tested is total testosterone. But total T is only part of the picture. Another item that should be tested for is sex hormone binding globulin (SHBG). As the name implies, this hormone binds to T rendering it not bioavailable to the body. Free T is the next item that should be tested for. This is the amount of T that is not bound to SHBG and thus is "free" to be used by the body.

It would also be good to test for some of the T precursors. "Testosterone is made through a complex series of steps, which can be simplified as follows: cholesterol to pregnenolone to progesterone/ dehydroepiandrosterone [DHEA] to androstenedione ["andro"] to testosterone" (Faigin, p.329).

This background is important when looking at studies on the relationship of diet and testosterone as some of these different items are often mentioned in the reports. Also, the term "androgens" is often used to refer collectively to T and its precursors.

Research on Testosterone and Fat

The first issue to consider in regards to diet and testosterone is fat intake. A study conducted in 1997 at my alma mater looked at this issue.

In the Penn State study, the subjects eating moderate fat exhibited higher testosterone levels than the subjects eating low fat - this finding merely confirmed previous studies demonstrating that dietary fat is positively linked with testosterone levels.

More impressively, the Penn State researchers showed that the effect of dietary fat on testosterone levels depended on the kind of fat consumed. Specifically, they found that monounsaturated and saturated fat raise testosterone levels, but polyunsaturated fat does not (Faigin, pp. 329-330, emphasis in original).

Other studies confirm these results. For instance, in a 2005 study, "39 middle-aged white, healthy men (50 to 60 yr) were studied while they were consuming their usual high fat, low fiber diet and after 8 weeks modulation to an isocaloric low fat, high fiber diet." The results of the dietary change were a reduction in total T and free T and some of the T-precursors.

The researchers concluded, "Metabolic clearance rates of T were not changed and production rates of T showed a downward trend while on low fat diet modulation. We conclude that reduction in dietary fat intake (and increase in fiber) results in 12% consistent lowering of circulating androgens levels without changing the clearance" (Wang).

A 1984 study had similar results. "The possible effect of dietary fat content and the ratio of polyunsaturated to saturated fatty acids (P/S-ratio) on serum sex hormones was studied in 30 healthy male volunteers. The customary diet of the subjects, which supplied 40% of energy as fat (mainly from animal sources, P/S-ratio 0.15) was replaced for a 6 weeks period by a practically isocaloric experimental diet containing significantly less fat (25% of energy) with a higher P/S-ratio (1.22) and other environmental factors were stabilized."

As a result of the dietary change, there was a 15% drop in total T, with corresponding drops in free T and androstenedione. The researchers concluded, "Our results indicate that in men a decrease in dietary fat content and an increase in the degree of unsaturation of fatty acids reduces the serum concentrations of androstenedione, testosterone and free testosterone" (Hamalainen).

And, "An interesting 1987 study put men on a high-fat (about 50 percent of calories from fat) for 2 weeks, then had them switch to a low-fat diet (about 10 percent fat) for 2 weeks. Their free testosterone-the part that's available for use in building muscle-dropped 21 percent on the low-fat diet" (Schuler, p.86).


The overall consensus of these studies and others that could be cited is that a low fat diet lowers total T and/ or free T levels while a moderate to high fat diet raises T levels. This is why Men's Health magazine reported, "… despite the antifat message we're bombarded with, it turns out that diets too low in dietary fat are actually harmful to healthy T levels" (Thorton, p.154).

Moreover, it is not just any fat, but saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) that raise T levels. Polyunsaturated fatty acids (PUFA) do not.

As such, "… restricting total fat intake ­and replacing saturated fat with polyunsaturated fat (exactly what the experts are telling you to do) would appear to be the perfect prescription for lowering your testosterone levels! (Faigin, p.330; emphases in original).

However, it is not necessary to consume a lot of saturated fat. A response to a letter on asking about how to raise T levels on reported about a study that showed, "Men with the highest testosterone levels ate nuts! Yes, monounsaturated fat seems to increase testosterone levels, so include nuts, olive oil, canola oil, and peanut butter!"

Moreover, foods high in healthy Omega 3s fatty acids would also be good sources of T-raising fat. The best sources of omega 3s are fatty fish like mackerel, herrings, sardines, tuna, sturgeon, and salmon. But they are also found in plant foods like walnuts, pumpkin seeds, flax seeds, flax seed oil, and canola oil (Collins).

It is for this reason that Men's Health magazine recommends, "… keep your consumption of fat-preferably in the form of monounsaturates and omega-3s-up around 35-40 percent, the amount research shows to be optimal for robust T levels" (Thorton, p.154).

In my book , God-given Foods Eating Plan, I discuss in detail the health benefits of a moderate fat diet. For instance, "Specifically, this would be a diet that has about 30-40% of calories from fat, but, and this is important, the majority of these fat calories should be in the form of the ‘good' monounsaturated kind."

I then cite a study from Penn State that showed such a diet reduced the risk of heart disease by 21% while a low fat diet reduced it by only 12%. I then concluded that such a diet, "could be the most heart-protective of all." So it is possible to have a healthy, moderate-fat diet.

Protein Intake

Part One of this article discussed that a high protein intake raises growth hormone levels. But when it comes to testosterone, it is difficult to draw a firm conclusion from the evidence. Some studies find that a high protein intake lowers T levels. For instance, in the following study, a "r=" that is negative (-) means the item was associated with lower T levels, while a "r=" that is positive means it is associated with higher T levels.

Significant correlations were observed between preexercise T and percent energy protein (r = -0.71), percent energy fat (r = 0.72), saturated fatty acids (g.1,000; r = 0.77), monounsaturated fatty acids (g.1,000; r = 0.79, the polyunsaturated fat-to-saturated fat ratio (r = -0.63), and the protein-to-carbohydrate ratio (r = -0.59). (Volek).

So a positive association was seen with total fat and saturated fat, while a negative association was seen with protein and polyunsaturated fat. However, studies such as this one only look at total T levels. When free T is considered, a somewhat different picture emerges.

For instance:
Testosterone concentrations in seven normal men were consistently higher after ten days on a high carbohydrate diet (468 +/- 34 ng/dl, mean +/- S.E.) than during a high protein diet (371 +/- 23 ng/dl, p less than 0.05) and were accompanied by parallel changes in sex hormone binding globulin (32.5 +/- 2.8 nmol/l vs. 23.4 +/- 1.6 nmol/l respectively, p less than 0.01). By contrast, cortisol concentrations were consistently lower during the high carbohydrate diet than during the high protein diet (7.74 +/- 0.71 micrograms/dl vs. 10.6 +/- 0.4 micrograms/dl respectively, p less than 0.05) (Anderson).

So the high carb diet raised total T levels and lowered cortisol levels. These are both beneficial effects. However, the raising of SHBG is problematic. This is discussed further in the next study.

A 2001 study was conducted that looked at the relationship of protein intake to SHBG, "Using data from the Massachusetts Male Aging Study we examined cross-sectional relationships between dietary components and SHBG levels in 1552 men (aged 40-70 yr) for whom these factors were known." The study found that the higher the protein intake the lower the levels of SHBG.

The researchers concluded, "Thus, diets low in protein in elderly men may lead to elevated SHBG levels and decreased testosterone bioactivity. The decrease in bioavailable testosterone can then result in declines in sexual function and muscle and red cell mass, and contribute to the loss of bone density" (Longcope).

So a high protein intake lowers total T levels and raises cortisol levels. These are both detrimental effects. However, protein lowers SHBG and increases GH secretion. These are both beneficial effects. Given these conflicting effects of protein on hormone optimization, the best recommendation would probably be to keep protein intake at a moderate level. But before discussing what "moderate" would be, another issue in regards to protein needs to be addressed.


The source of protein can make a difference as to its effect on T levels. Specifically, is the protein from meat or non-meat sources?

A 1989 study looked at this issue. "The purpose of this study was to determine the levels of unconjugated steroids and steroid glucuronides as well as sex hormone-binding globulin (SHBG) among normal adult men who were either omnivorous or vegetarians."

Blood tests were done on "white volunteers ranging from 25-35 years of age." The levels of total T, DHEA, and other T-precursors were similar in the two groups. But, "Vegetarian group showed a higher levels of sex hormone-binding globulin (SHBG) while the free androgen index (FAI; calculated by the ratio testosterone/SHBG) was lower in this group."

The researchers concluded, "Our data suggest that in a vegetarian group, less testosterone is available for androgenic action" (Belanger).

Cholesterol is the building block of testosterone, so it would make sense that a meat-eating, cholesterol consuming diet would yield more of the big T that a vegetarian diet would. And indeed, that's what a 1985 study found when it looked at a large cross-section of omnivores and vegetarians. What was surprising was how significant the difference was: The meat-eaters actually had 36 percent more T than the guys who stuck to rabbit food….

A 1989 study found pretty much the same thing: The meat-eaters ate more fat, more cholesterol, more saturated fat, and less fiber than the vegetarians and had 31 percent more testosterone (Schuler, p.86).

Another study had similar results:
A Dutch study published in 1992 looked at changes in T levels on these two diets. A group of young male endurance athletes ate and trained on each diet for 6 weeks. (Half started on the meat-rich diet, half on the vegetarian diet; then they switched.) Total testosterone declined 35 percent when the athletes used the vegetarian diet (Schuler, p.76).

So the consumption of meat raises T levels while a vegetarian diet lowers T levels. Another issue in regards to vegetarians could be that soy is often included as a source of protein on a vegetarian diet. But research shows that soy can lower T levels (Di Pasquale, p.44; see also my article Soy: Health Food or Food to Avoid?).

However, even the inclusion of dairy and eggs would not correct the problem. "Dutch research shows that athletes had higher testosterone levels when eating meat-based protein, compared with other sources, such as dairy and eggs" (Thorton, p.155). So even an ovo-lacto-vegetarian diet would not be good for T levels.

And this shows that it is not the fat and cholesterol in meat that raises T levels as these are found in dairy and eggs. It has something to do with meat itself. And it should be noted that "meat" is usually used in a general sense to refer to red meat, poultry, and fish. So it is not necessary to consume a diet high in saturated fat and cholesterol. A diet rich in healthy fats and lean meats would provide the T raising effects just as well as one high fatty meats and thus high in saturated fat and cholesterol.

Moreover, "… the omega-3s can provide an excellent hedge against worries about cholesterol. Blood pressure, clotting, immune response, insulin resistance, and triglyceride levels are all positively affected. Even in cases where dietary cholesterol is increased, omega-3s may aid in actually lowering cholesterol." And, "… factors that can decrease the tendency of LDL ["bad" cholesterol] to oxidize (such as the use of monounsaturated and marine oils) can negate any harmful effects a higher-[saturated] fat diet may have on CVD [cardio-vascular disease]" (Di Pasquale, pp. 82, 91).

So even if more saturated fat and cholesterol are consumed, if the above recommendation to consume foods high in MUFAs and Omega-3s is followed, then possible negative effects would be negated. A copious consumption of veggies (as was recommended in Part One) would further help to negate any possible deleterious effects.

And with the inclusion of healthy fats and veggies, a meat-based, omnivore diet would be healthier than a vegetarian diet as it would enhance and optimize hormones, rather than having a deleterious effects on hormones like a vegetarian diet does.

It is for these reasons that Men's Health magazine declared, "In fact, many of the classic dietary commandments-restrict your overall calories, eat a lot of roughage, avoid animal flesh-are a virtual recipe for lowering T." And "Perhaps the ideal diet to drop your testosterone is high fiber and vegetarian-and the ideal way to raise it is the red-meat approach" (Thorton, p.154).

Another problem with a vegetarian diet is that it lowers IGF-1 levels (Di Pasquale, p.44). Vegetarian diets are also inevitably low in protein and usually high in carbs, which would lead to depressed GH levels.

Given the above, the following study is not surprising:
An interesting 1999 study compared the muscle-building effects of two different diets on 19 overweight, sedentary men ages 51-69. Nine of the men ate a diet in which half of the protein came from meat and other animal sources-a typical Western diet. The other 10 ate a vegetarian diet that included dairy and eggs (but, obviously, no meat). Both groups were put on the same weight-lifting program.

Look at the results that the study found after 12 weeks:
Meat-Eaters: Muscle: Gained 3.74 lb.; Fat: Lost 2.86 lb.
Vegetarians: Muscle: Lost 1.76 lb.; Fat: Gained: 0.22 lb. (Schuler, pp.75,76).

I was hoping to conclude this article in two parts. But this second part is already too long. So a Part Three will be used to conclude this discussion on testosterone. It will also look at how to organize the various recommendations from this article into a dietary plan.

Anderson KE, Rosner W, Khan MS, New MI, Pang SY, Wissel PS, Kappas A. Diet-hormone interactions: protein/carbohydrate ratio alters reciprocally the plasma levels of testosterone and cortisol and their respective binding globulins in man. Life Sci. 1987 May 4;40(18):1761-8. PMID: 3573976.

Belanger A, Locong A, Noel C, Cusan L, Dupont A, Prevost J, Caron S, Sevigny J. "Influence of diet on plasma steroids and sex hormone-binding globulin levels in adult men." J Steroid Biochem. 1989 Jun;32(6):829-33. PMID: 2526906., letters.

Collins, Anne. Omega-3 and Omega-6 Essential Fatty Acids. Essential Fatty Acids in Fish.

Di Pasquale, Mauro. The Anabolic Solution for Powerlifters. N/A. 2002. For details on this book and nutrition program, see the Metabolic Diet Web site.

Faigin, Rob. Natural Hormonal Enhancement. Extique Publishing: Cedar Moutaint, NC. 2000. For details on this book and nutrition program see the Extique Web site.

Hamalainen E, Adlercreutz H, Puska P, Pietinen P. "Diet and serum sex hormones in healthy men." J Steroid Biochem. 1984 Jan;20(1):459-64. PMID: 6538617.

Longcope C, Feldman HA, McKinlay JB, Araujo AB. "Diet and sex hormone-binding globulin." J Clin Endocrinol Metab. 2000 Jan;85(1):293-6. PMID: 10634401.

Schuler, Lou. The Testosterone Advantage Plan. Rodale: USA, 2002.

Thorton, Jim. " Maximum Testosterone." Men's Health. April, 2005, pp. 146-155,182.

Volek JS, Kraemer WJ, Bush JA, Incledon T, Boetes M. Testosterone and cortisol in relationship to dietary nutrients and resistance exercise. J Appl Physiol. 1997 Jan;82(1):49-54. PMID: 9029197.

Wang C, Catlin DH, Starcevic B, Heber D, Ambler C, Berman N, Lucas G, Leung A, Schramm K, Lee PW, Hull L, Swerdloff RS. "Low Fat High Fiber Diet Decreased Serum and Urine Androgens in Men." J Clin Endocrinol Metab. 2005 Mar 1. PMID: 15741266.

Zeolla, Gary. Creationist Diet: Nutrition and God-given Foods According to the Bible. 1stBooks, 2000.


Hormones and Diet: Part Three: Testosterone/ Dietary Plans

God-given Foods Eating Plan:
For Life-long Health, Optimization of Hormones, Improved Athletic Performance

Hormones and Diet: Part Two: Testosterone. Copyright ©  2005 By Gary F. Zeolla.

Disclaimers:  The material presented in this article is intended for educational purposes only. The author is not offering medical or legal advice. Accuracy of information is attempted but not guaranteed. Before undertaking any diet, exercise, or health improvement program, one should consult your doctor. The author is in no way responsible or liable for any bodily harm, physical, mental, or emotional, that results from following any of the advice in this article.

The above article first appeared in the free FitTips for One and All email newsletter.
It was posted on this site October 1, 2005.

Nutrition: Hormones and Diet

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