T Nation

I LOVE Sweet Taters BUT!!!


During a search and education on a different subject i am currently dealing with I stumbled upon this. I love sweet potato's and eat them usualy 3-4 times a week with breakfast But this has me possibly rethinking it.

Not in totality as I am still havin my tater in the morning but interesting none the less and just though I would post my finding here for some thoughts??

I know CT and others use sweet potato's as a GREAT complex carb often.

Most noteable to me were the significant rise In SHBG and near significant rise in estrone, estradiol and SHBG. Then no change in things such as T.

So the T has to be further bound and less free T and higher E. Not good eh' at first glance.


Estrogenic effect of yam ingestion in healthy postmenopausal women.

Wu WH, Liu LY, Chung CJ, Jou HJ, Wang TA.

Graduate Program of Nutrition, Department of Human Development and Family Studies, National Taiwan Normal University, Taipei, 106, Taiwan. t10005@cc.ntnu.edu.tw

OBJECTIVE: Yam (Dioscorea) has been used to treat menopausal symptom folklorically. This study was to investigate the effects of yam ingestion on lipids, antioxidant status, and sex hormones in postmenopausal women. METHODS: Twenty-four apparently healthy postmenopausal women were recruited to replace their staple food (rice for the most part) with 390 g of yam (Dioscorea alata) in 2 of 3 meals per day for 30 days and 22 completed the study. Fasting blood and first morning urine samples were collected before and after yam intervention for the analyses of blood lipids, sex hormones, urinary estrogen metabolites and oxidant stress biomarker. The design was a one arm, pre-post study. A similar study of postmenopausal women (n = 19) fed 240 g of sweet potato for 41 days was included as a control study. Serum levels of estrone, estradiol and SHBG were analyzed for this control group. RESULTS: After yam ingestion, there were significant increases in serum concentrations of estrone (26%), sex hormone binding globulin (SHBG) (9.5%), and near significant increase in estradiol (27%). No significant changes were observed in serum concentrations of dehydroepiandrosterone sulfate, androstenedione, testosterone, follicular stimulating hormone, and luteinizing hormone. Free androgen index estimated from the ratio of serum concentrations of total testosterone to SHBG decreased. Urinary concentrations of the genotoxic metabolite of estrogen, 16alpha-hydroxyestrone decreased significantly by 37%. Plasma cholesterol concentration decreased significantly by 5.9%. Lag time of low-density lipoprotein oxidation prolonged significantly by 5.8% and urinary isoprostane levels decreased significantly by 42%. For the control subjects fed with sweet potato, all three hormone parameters measured were not changed after intervention. CONCLUSION: Although the exact mechanism is not clear, replacing two thirds of staple food with yam for 30 days improves the status of sex hormones, lipids, and antioxidants. These effects might reduce the risk of breast cancer and cardiovascular diseases in postmenopausal women.


Boy I figured someone would bite on this. Guess I should have posted one of the HUNDREDS of creatine questions if I wanted interest... Like ah "Will creatine make my heart explode and stuff" LOL



Uh...I don't think you should worry, unless you're a postmenopausal woman : )


So you honestly feel that what gives such a HUGE change in postmenopausal women would have No effect on the average everyday man or woman?? Just because that is what the study was focused on doesnt mean it has no relevance.

I mean many studies that people take as gold are on mice and monkeys, not even the same speices.

I just cant see how it could have some turnover??

Still had a Big old sweet Potato today however.


this is interesting to me Phill, because a sweet potato is always part of my post-Surge(s) monster meal on squat day and deads day.

some things to remember: though their names are used interchangeably, sweet potatoes and yams are actually quite distinct. the study you've referenced used yams (Dioscoreaceae) specifically. sweet potatoes have the clear edge nutritionally and since they are grown here in the US, (yams are not) you can feel quite sure you're getting the good stuff without the possible "bad" stuff this study suggests.

a couple of google's top search results:


Would you guys suggest that one eat sweet potatoes rather than canned yams?


Steven thing is like the above said what is called a Yam here is NOT a yam.Yams are from Africa and you would be HARD pressed to find one here or anywhere in abundance. Yams are much larger have a bit lower GI, and well arenty found much. All thet canned yam etc will be the same sweet potato used in this stude.

Hope that helps,


Chillain, Ah yes but duid you miss this in the studies

This is the one that showed the Worst of the two studies above.

Food for thought (pun intended)



Am I missing something? When I read it it said that yam's changed the hormone levels and sweet potato (which was a control for the study) did nothing!


I do beleive you are right. Nice catch and BAD read on my part.

So steer clear of the REAL yams eat them sweet taters.


The things in the store that are usually labeled "yams" are just orange sweet potatos, as are the yams in the cans. As previously posted, you'd have to go to an exotic foods market for any chance at a true yam.


Side note: those orange sweet potatos make great pie and can even be mixed 50/50 with pumpkin for a great tasting (and lower GI) dessert. My wife watches me cook the pies, but my kids ate them like they were just pumpkin pie (and going out of style).


I am not convinced that this study was conducted with reasonable controls so that anything can be concluded from it. Why did one group eat 60 meals with 390 g over 30 days (that's a lot of yam), while the other ate an unknown number of meals with 240 g for 41 days? I am not convinced that this "one arm" design with a "control study" provides either internal OR external validity here.

And I would not assume that even a true effect on the hormones of postmenopausal women would generalize to healthy young males. Feedback loops generally keep hormone levels within certain limits, and postmenopausal women have very low levels to begin with.


Try caribbean specialty food stores too if you have such a section of town where you live.


Yeah the sweet potatoes we get down here in the Caribbean arnt red or orange. They are plain old white.

That better or worse?


Not sure Just very ODD. LOL Sun bleached from the trip maybe.