Originally Posted by Eric3237
it's gonna take a huge amount of those weak plant estrogens to effect you test, and its gonna take that extended period of time.
Now, do those phyto-estrogens do more than just bind to estrogen receptors thereby blocking them, or do they initiate estrogen production?
I'm sure you've read that they do on a lot of the BB web sites. But the studys that found this were done on mice and rats. If you want to believe that than we have to relax the criteria that has been initiated on this thread. If verb's rhesus monkeys weren't good enough, then...
And all those consclusive
studies? Remember the words statistically insignificant? Add this:
Agency for Health Care Research and Quality (AHRQ)
Authors: Balk E, Chung M, Chew P, lp s, Ramon G, Kupelnick B, Tafsioni A, Sun Y, Walk B, Devine D, Lau J
Measures of endocrine function were reported from 50 trials in 47 articles. Five studies with a total of 179 participants reported testosterone levels in healthy males before and after soy consumption. Four of these trials found a statistically non-significant decrease in testosterone levels. The small total number of subjects as well as the low quality of these studies precluded any meaningful conclusion. No statistically significant effect was found on FSH level, which is commonly measured in the initial evaluation of male and female infertility; results were conflicting.
Look, I've done a lot of this kind of research. It used to be my job to do this kind of research. Things are just never simple and cut and dry. People can believe what they want to believe. But I would never tell someone, "Look, soy is gonna lower your test." Because I don't base things on what I believe.
I either know or don't know. And I don't know if soy really effects your test.
I do think it is likely that a large amount of soy can lower test, but I don't know just based on a bunch of faulty studies.
Do we understand the term statistically insignificant? It means the the results can be explained by normal metabolic processes, i.e. natural fuctuations in test level that stay within a normal range.
You can make an informed decision based on the info you have. I certainly never use soy powder and only eat some soy in my diet. But I'm not gonna sublime an entire industry or make claims on the bio-availibility of soy based on outdated research.
Here is a good overview of some of the problems with this kind of food research:
This report dealt with a broad range of health conditions and endpoints, thus it is difficult to focus research recommendations on a specific area. Common to most bodies of evidence regarding medical fields, better quality, well-reported, larger and longer duration studies are needed to address the questions of interest. Future studies should fully report the components of soy products being tested; compare different doses, soy products, and populations; more closely evaluate the effects of different soy components, including non-protein, non-isoflavone components; fully consider the types of foods being replaced by soy products and the controls being used; and use the CONSORT statement as a guide to designing and reporting studies. 3,4
Conducting clinical trials in the area of health effects of food substance is fraught with difficulties. There is a complex interplay among the various components and potentially active substances within the foods and with other foods, dietary variations, as well as with other lifestyle and clinical variations among individuals. Controlling for these factors is difficult within a trial. Interpreting discrepant results among trials is even more difficult. Isoflavones are believed to be the key active substance in soy, but this is by no means certain. Little data suggest that the amount of soy isoflavones is associated with an incremental effect and studies of soy protein with little or no isoflavones frequently had similar effects as isoflavone studies. Difficulties with attempting to ascribe a food health benefit to a specific component of the food are highlighted by the recent spate of disappointing results from antioxidant trials, which suggest that the evaluation of potential nutrient benefits may need a paradigm different from the traditional clinical trial model.
The bioavailability of an ingested nutrient may also be an important factor in the determination of the beneficial effect. Several factors may affect the bioavailability of ingested nutrients:
- Absorption rate, affected by the interactions with competitive nutrients, the usual diet compositions, and types of foods or supplements.
- Incorporation rate into the blood stream, in which complex mechanisms might be involved, such as the functions of facilitated transporters, receptors on the membrane, or cellular binding proteins.
- Metabolism of the intestinal bacterial environment.
Any one of these factors alone does not determine the bioavailability. In order to gain insights on the question of dose-response relationship, we not only need the information on the soy isoflavone contents, including types and amount, but also on the bioavailability of the ingested soy isoflavones.
Unfortunately studies that attempt to control for the myriad factors that interfere with clear interpretation of the effect of food products such as soy tend to be highly artificial, with little applicability to the average person. Clarity is needed to define what study questions are of interest. Metabolic laboratory studies or investigations of highly structured or restricted diets (such as those where soy protein constitutes the bulk of daily protein consumption) are of potential value only to possibly determine which components of soy are bioactive or to determine what extremes of diet may be necessary to achieve a benefit. Studies that substitute practical amounts of soy products into average people's diets would better address the question of whether people should make the effort to include more soy in their diets, but these studies will invariably be difficult to interpret. An exception to this may be studies of soy isoflavone supplements (e.g., non-food capsules), which may be interpreted more like usual drug trials.
Carefully controlled efficacy studies (those conducted under the artificial conditions of a clinical trial) may still be useful to pin down the relative effects of various components of soy. Once this is better clarified, more practical effectiveness studies (that aim to test the value of an intervention in more real-world scenarios) with feasible interventions might be more important.
Hey, for every "expert" who says soy is not good for bodybuilders you can find another who say it is, or advocates mixing soy and whey in you diet, so on and so forth.
Who really knows? I say don't be too paranoid about soy. The jury is still out, and will be for a good long time.