I've just been reading this study and just wanted to know if someone could clear it up for me.
Nutrition-endocrine interactions: Induction of reciprocal changes
in the 4- 5a-reduction of testosterone and the cytochrome
P-450-dependent oxidation of estradiol by dietary
macronutrients in man
The in vivo biotransformations of drugs known
to be metabolized by enzymes localized in the endoplasmic reticulum
of liver can be greatly altered by diet in humans, as we have
shown previously. Steroid hormones also are metabolized extensively
by hepatic microsomal enzymes; therefore, we examined
the possibility that testosterone and estradiol biotransformations,
as assessed with radiolabeled tracer methods, could be influenced
by dietary macronutrients. Normal males were fed a high-protein
diet for 2 weeks, followed by a high-carbohydrate diet for an additional
2 weeks. The A4-5a-reduction of testosterone was considerably
diminished, while the cytochrome P-450-dependent hydroxylation
of estradiol at the C2 position was substantially
enhanced during ingestion of the high-protein diet as compared
with the high-carbohydrate diet. These results indicate that dietary
macronutrients can significantly alter major metabolic pathways
for testosterone and estradiol in man. The mechanism by
which reciprocal changes in the A4-5a-reduction of testosterone
and the cytochrome P-450-mediated oxidation of estradiol are
produced by diet is not known. Similar changes in steroid A4-5areduction
and cytochrome P-450-dependent chemical oxidations
have been observed in circumstances in which the mixed-function
oxidase system in liver is induced by agents such as phenobarbital,
hexachlorobenzene, dioxin, and polyhalogenated biphenyls. Thus,
the alterations in steroid hormone metabolism produced by dietary
macronutrients in man mimic those that can be produced by
drugs and environmental chemicals.
The A4-5a-reductive metabolism of testosterone was measured
in all eight subjects by intravenous injection of a single
2.0-,ACi (1 Ci = 37 GBq) dose of [4-14C]testosterone (50 ,ACi/
mmol), followed by isolation and measurement of its radiolabeled
5a and 5,B metabolites excreted in urine as described (34,
35). This technique has been applied extensively to the study
of steroid A4-5a-reductase activity in man and permits quantitation
of this metabolic pathway for steroid substrates of appropriate
structure
Just for clarity, although its showing up as A4-5a-reductase, in the article its delta4. So my question is whether this delta4-5a-reductase is the same 5a-reductase that turns testosterone into DHT. The study found a 50% increase in the delta4-5a-reductase activity when switched from a high-protein diet (44% calories from protein, 35% from carbs) to a high-carbohydrate diet (70% calories from carbs, 10% from protein). So does a high-protein diet lower DHT? Perhaps someone with a little more of a scientific background can analyze this better for me. Thanks.
Nutrition-endocrine interactions: Induction of reciprocal changes
in the 4- 5a-reduction of testosterone and the cytochrome
P-450-dependent oxidation of estradiol by dietary
macronutrients in man
The in vivo biotransformations of drugs known
to be metabolized by enzymes localized in the endoplasmic reticulum
of liver can be greatly altered by diet in humans, as we have
shown previously. Steroid hormones also are metabolized extensively
by hepatic microsomal enzymes; therefore, we examined
the possibility that testosterone and estradiol biotransformations,
as assessed with radiolabeled tracer methods, could be influenced
by dietary macronutrients. Normal males were fed a high-protein
diet for 2 weeks, followed by a high-carbohydrate diet for an additional
2 weeks. The A4-5a-reduction of testosterone was considerably
diminished, while the cytochrome P-450-dependent hydroxylation
of estradiol at the C2 position was substantially
enhanced during ingestion of the high-protein diet as compared
with the high-carbohydrate diet. These results indicate that dietary
macronutrients can significantly alter major metabolic pathways
for testosterone and estradiol in man. The mechanism by
which reciprocal changes in the A4-5a-reduction of testosterone
and the cytochrome P-450-mediated oxidation of estradiol are
produced by diet is not known. Similar changes in steroid A4-5areduction
and cytochrome P-450-dependent chemical oxidations
have been observed in circumstances in which the mixed-function
oxidase system in liver is induced by agents such as phenobarbital,
hexachlorobenzene, dioxin, and polyhalogenated biphenyls. Thus,
the alterations in steroid hormone metabolism produced by dietary
macronutrients in man mimic those that can be produced by
drugs and environmental chemicals.
The A4-5a-reductive metabolism of testosterone was measured
in all eight subjects by intravenous injection of a single
2.0-,ACi (1 Ci = 37 GBq) dose of [4-14C]testosterone (50 ,ACi/
mmol), followed by isolation and measurement of its radiolabeled
5a and 5,B metabolites excreted in urine as described (34,
35). This technique has been applied extensively to the study
of steroid A4-5a-reductase activity in man and permits quantitation
of this metabolic pathway for steroid substrates of appropriate
structure
Just for clarity, although its showing up as A4-5a-reductase, in the article its delta4. So my question is whether this delta4-5a-reductase is the same 5a-reductase that turns testosterone into DHT. The study found a 50% increase in the delta4-5a-reductase activity when switched from a high-protein diet (44% calories from protein, 35% from carbs) to a high-carbohydrate diet (70% calories from carbs, 10% from protein). So does a high-protein diet lower DHT? Perhaps someone with a little more of a scientific background can analyze this better for me. Thanks.
