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.
Vegetarianism
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).
Moreover:
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).
