On Short Notice: Teas & Prostate, Metformin & Amenorrhea, Stevia & High, Omega-3 & Low Cortisol, Aminos & Weight Control, Nordic Hamstring Exercise & 20% More Power!

Image 1: This would be a case where metformin probably won't help you to get your menses back - unless this is just one of your "yous" and you are taking high doses of anti-psychotics, of course.

In view of the fact that I have piled up way more "On Short Notice" items than I can possibly squeeze into one installment, today's news on the right tea (green or black) for prostate cancer, the purported anti-obesity effects of leucine and alanine, which turn out to be inferior to those of whole protein, the anti-amenorrhea and weight loss effects of metformin in women on anti-schizophrenic drug and how this relates to PCOS, the surprising N=1 cortisol-raising, high blood pressure and water retaining effects of stevia, the stress and weight loss reducing effects of omega-3s and high DHA levels in the brain, and an effective yet rarely used hamstring exercise, the "Nordic hamstring exercise", will be complemented by another installment of "On Short Notice" either tomorrow (in case I don't find the time to write the next installment of the Circadian Rhythm Series) or earlier next week... but enough of these organizational matters, let's see what we have in stock, here:

• Differential effects of green and black tea on prostate cancer risk While we are, yet again, only dealing with epidemiological shenanigan in a population living in a, if not the juggernaut of the far east, the >50% increase in hazard risk in the 27,293 men from the Singapore Chinese Health Study Julia A. Montague and her colleagues report for men who drink 1 cup of black tea per day is somewhat alarming (Montague. 2012). The fact that the hazard risk decreases to +17% with more than 2 cups of black tea does yet suggest that this is nothing but a statistic outlier. That said, black tea is (at least based on the results of this study) overall probably as benign as green tea, which is totally devoid of statistical beneficial or detrimental effects on prostate cancer risk in this cohort of normal-weight men in their middle to late 50s.
  This result does by the way not conflict with previous research, which did - if anything - only suggest a "borderline significant" beneficial effect of green tea and absolutely no effect of black tea on prostate cancer risk (Zheng. 2012). Apropos prostate cancer, just in case you missed it I highly suggest you take a look at my brief write-up on the recently published "red meat will give you prostate cancer study" before you decide on whether or not you got to stop eating meat for the sake of your prostate.

• 

  Figure 1: If  ~50g of leucine and alanine /kg chow are good, then 500g of whey are magic; makes you wonder, why you would want to add just one amino acid, instead of more protein, no?

  "Dietary L-leucine and L-alanine supplementation have similar acute effects in the prevention of high-fat diet-induced obesity",  that's the somewhat ill-chose title of a recently published paper by Anne Freudenberg, Klaus J. Petzke, Susanne Klaus from the German Institute of Human Nutrition in Potsdam-Rehbruecke which does not show that the ingestion of l-leucine or alanine, but rather an isocaloric high protein diet version of the high-fat diets the researchers fed their 10-week-old male C57BL/6 mice, prevented them from getting obese (Freudenberg. 2012).
  While the high fat + complete protein mice hardly gained any body fat, the high fat + leucine and high fat + alanine (both diets were "adequate" in protein and contained 100g whey + 60g leucine and 100g whey + 45g alanine, respectively)  got only significantly less fat compared to their peirs on the 100g whey only diet control HFD diet. Now, the high protein mice (500g of whey per kg chow; =5x over baseline) simply consumed less energy, but so did the mice on the leucine and alanine enhanced diets, so that the title of the study is not just misleading, it also disguises the most important result of the study, which is high protein diets keep mice lean.
• "Cure-it-all-drug" metformin helps with anti-psychotic induced amenorrhea and weight gain, as well. If metformin was not (a) no longer protected by patent rights and (b) would not basically work via similar mechanisms as exercise I would really begin to smell fraud over the ever-extending list of pathologies this 1920s medication is good for (this is when it was originally discovered, it took however until 1958 before researchers realized the potentials and a pharma company introduced it to the UK market). New to the list are the negative side-effects women experience in response to anti-psychotic treatments. In a recently documented experiment, 48 women (ages 18-40 years) with amenorrhea and weight gain in response to clozapine, olanzapine, risperidone, or sulpiride (all anti-psychotic drugs administered to treat schizophrenia) received a dose of 1,000mg of the wonder-molecule per day (Wu. 2012). After 2 months 25% of the women had resumed menstruation, after another 2 weeks it were 80% and after 3 months all women were eumenorrheic, again (of the placebo group only 2 resumed menstruating). Instead of gaining another 2kg of body weight, they had lost 2kg and the previously thwarted prolactin, LH, and testosterone levels, as well as the LH/FSH ratio had normalized.
  Probably, some of you may now ask themselves: Will this work for me as well - though I am not taking anti-psychotics? I would love I could answer this question, but aside from polycystic ovarian syndrome (PCOS), where we have a couple of trials in which metformin was used with success (cf. Velazquez. 1998; Bela. 2009; Palomba. 2009), the scientific evidence is scarce and in view of the fact that we know even less about the underlying mechanisms by which risperidone & co cause amenorrhea and weight gain than about the almost magical omnipotence of metformin I honestly can't tell. One thing that comes mind, where metformin is yet very unlikely to of any use is diet or exercise induced amenorrhea (overtraining and undereating), because this form of amenorrhea presents with a totally different hormonal profile, with low levels of basically all reproductive hormones.
• Stevia as cortisol promoter? Case study: Bloating, high blood pressure and malaise in a young previously healthy woman. Before I go on, let me briefly remind you that the events that are described in a recent case report from the University of Iowa Hospitals and Clinics may should be regarded with the degree of caution that is indicated whenever we are talking about case reports, specifically because stevia does actually have a pretty decent safety profile (aside from the occasional allergic reactions you will see with almost every foreign molecule you put into your body, obviously).

  

  Figure 2: If you block the 11bHSD2 enzyme that will convert cortisol into inactive cortisone, you are in trouble and a bloated tummy is certainly your least problem, not because "cortisol is bad", as common sense would dictate, but because not being able to manage it is bad (img. Michael. 2008)

  When a 32 year old Caucasian woman presented with generalized edema (feet, hands and face) that had persisted for over six months at her Dr office and was found to to suffer from pre-hypertension (138/88 mmHg) and hypokalemia (3.4 mM/l) that was brought about by a decline in serum aldosterone and plasma renin activity and corroborated by a concomitant  increase in the plasma cortisol/cortisone ratio, most Dr.'s would probably have thought of licorice intoxication. As it turned out, it were neither the glycyrrizinic acid, not the glycyrrhetinic acid from licorice which brought about these problem, but rather the stevia the lady had been using for over 9 months, now. Obviously, the sweetener (from an undisclosed brand) had blocked the 11 beta-hydroxysteroid dehydrogenase Type 2 (11-beta-HSD 2, see figure 2) enzyme that's responsible for the conversion (="deactivation") of cortisol to cortisone - with all the negative side effects of the subsequent 12x elevation of the ratio of active to inactive corticosteroids (Esmail. 2012).
  Now, I am certainly not suggesting that this is going to happen to everyone, but it could well be that the frequent reports of headaches people are developing after a couple of days "on stevia", could also be related to the effects the sweetener has on people with a certain genetic disposition. So, if you get a headache or start holding water like crazy, when you use stevia / stevia sweetened products, first try using a different brand (there have been issues with toxins in some products), make sure you have a pure stevia sweetener and not one with other sweeteners added (thx. to Amit for the reminder about erythritol that's in many products), switch to another preparation, e.g. from pure stevisoids to a a more "natural" extract and if all that does not help, just turn your back on it - you can live without it, I guarantee ;-)
• Omega-3's modulate adrenal activity What many people know from going overboard on fish oil has now been established in a recently published rodent study by Marie Hennebelle and her French (resident) colleagues (Hennebelle. 2012). The researchers fed a group of rodents a totally ALA free energetically restricted diet to produce male rats with brain phospholipid DHA levels that were 50% lower than those of the normal control. The 6 month-old rodents were then subjected to chronic restraint stress (6 h/d) for 21 days. As expected the rodents on the alpha linolic acid deficient diets had a much harder time coping with the torture they were exposed to and showed higher corticosterone levels, more pronounced behavioral abnomalies and slightly more pronounced weight loss in the 3-4 week of the 1-month experimental period. What's intriguing though is the the remarkable stress resistance (one could also say adrenal hypofunction ;-) in the rodents in a third experimental group, who had received an omega-3 enriched diet that boosted their brain DHA levels to 10% above normal: Compared to both the normal, as well as the omega-3 deprived rodents they had ~30% lower cortisol levels during week two and three of the experiment and lost only 50% of the weight their normal and ALA deprived peers did.
  That this is not necessarily a good thing for everyone is probably nothing I have to tell you. After all, the number of people who are hardly functioning due to over-supplementation with fish oil and (as this study would suggest) below normal stress responses is ever increasing. As with so many nutrients and supplements, it thus comes down to specificity and hitting the right ratios for you as an individual, again. And what's most important: Before you even start thinking about "fixing your adrenals" you should first take a look at the various stressors in your life. After all, the aforementioned fatigue is not simply a result of two much fish oil, but of its combination with a lifestyle which simply requires a robust and healthy cortisol response. You would not smoke weed to calm yourself down minutes before running away from a saber-toothed tiger, either, would you?

• 

  Video 1: These young ladies show you how it's done - well almost, you better go a little slower (click image to watch.

  Scientists confirm efficacy of nordic hamstring exercise - up to +20% increase in peak torque! What? You don't know the nordic hamstring exercise - I bet you do, but probably not by this name. Check out video 1 to the right and you will know what the 18 male players from a club in the English professional soccer leagues (mean±SD; age, 22.9±3.6 years; stature, 1.81±0.08 m; body mass 78.0±9.7 kg) did for 1x 2x5, 2x 2x6, 3x 3x6 and 3x 3x8 (sessions per week x sets x reps) during week 1-4 of the study period to improve their peak torque by up to 21% in all assessment conditions (90-61°, 60-31° and 30-0° of knee extension; cf. Iga. 2012).
  What is yet important is that you stick to an adequate temp and don't mess around and hurt yourself. In the study at hand, the velocity of the movement was standardized to 30°/s. If we assume that you go over the full ROM it must therefore take you 3s until your nose hits the ground (if you are afraid to hurt your nose, you may be interested in the SuppVersity EMG Series and the Best Leg + Hamstring Exercises ;-)

I hope you enjoy this more digestible format, having 20 of these items in one installment is - at least in my view - somewhat beside the point. Not that this would not be possible, but if I go by the average attention span of my real-life students, multiply it by 2x to accommodate for your superior cognitive abilities and personal interest in the topic, it appears prudent to call it a day for today. And if can't stand the 24h for the next SuppVersity news to be released, I suggest you simply like the SuppVersity Facebook Wall, where you will find another seven allegedly shorter news-items... about the wheat-allergens in soap (+ scary pic of what can happen, when you use those), for example or the news photo-based cholesterol test (a photo of your hands is all it takes), which is probably going to give the sales of statins another boost.

References:

• Billa E, Kapolla N, Nicopoulou SC, Koukkou E, Venaki E, Milingos S, Antsaklis A, Adamopoulos DA. Metformin administration was associated with a modification of LH, prolactin, and insulin secretion dynamics in women with polycystic ovarian syndrome. Gynecol Endocrinol 2009; 25:427–434
• Esmail S, Kabadi UM. Edema, Enigma: 11 B-Hydroxysteroid dehydrogenase Type 2 Inhibition by Sweetener “Stevia”. Open Journal of Endocrine and Metabolic Diseases, 2012, 2, 49-52.
• Freudenberg A, Petzke KJ, Klaus S. Dietary L-leucine and L-alanine supplementation have similar acute effects in the prevention of high-fat diet-induced obesity. Amino Acids. 2012 Jul 31.
• Hennebelle M, Balasse L, Latour A, Champeil-Potokar G, Denis S, Lavialle M, Gisquet-Verrier P, Denis I, Vancassel S. Influence of omega-3 Fatty Acid status on the way rats adapt to chronic restraint stress. PLoS One. 2012;7(7):e42142.
• Montague JA, Butler LM, Wu AH, Genkinger JM, Koh WP, Wong AS, Wang R, Yuan JM, Yu MC. Green and black tea intake in relation to prostate cancer risk among Singapore Chinese. Cancer Causes Control. 2012 Aug 3.
• Palomba S, Falbo A, Zullo F, Orio F Jr. Evidence-based and potential benefits of metformin in the polycystic ovary syndrome: a comprehensive review. Endocr Rev 2009; 30:1–50
• Wu RR, Jin H, Gao K, Twamley EW, Ou JJ, Shao P, Wang J, Guo XF, Davis JM, Chan PK, Zhao JP. Metformin for treatment of antipsychotic-induced amenorrhea and weight gain in women with first-episode schizophrenia: a double-blind, randomized, placebo-controlled study. Am J Psychiatry. 2012 Aug 1;169(8):813-21. 
• Velazquez EM, Mendoza S, Hamer T, Sosa F, Glueck CJ. Metformin therapy in polycystic ovary syndrome reduces hyperinsulinemia, insulin resistance, hyperandrogenemia, and systolic blood pressure while facilitating normal menses and pregnancy. Metabolism 1994; 43:647–654
• Zheng J, Yang B, Huang T, Yu Y, Yang J, Li D. Green tea and black tea consumption and prostate cancer risk: an exploratory meta-analysis of observational studies. Nutr Cancer. 2011;63(5):663-72.

DHEA the Slimming Hormone? Study Finds: Dehydroepiandrosterone Directly Inhibits Cortisol Synthesis in Rodent Adipocytes

After initially being hailed as the fountain of youth, the pharma-financed medical sciences dropped DHEA, when investors realized that a naturally occurring hormone would not be patentable. This and some discouraging and/or inconclusive results from long-term studies had DHEA literally disappear from the research scene for quite some time. Therefore, I am positively surprised that on the forthcoming European Congress of Endocrinology 2011 researchers from the Kobe University in Japan are going to present a paper (Tagawa. 2011) that shows that there may in fact be more to the initial findings of DHEA induced weight loss than follow-up studies would have it.

Tagawa et al. investigated the possible mechanism behind the weight loss effects of DHEA and found that there is a direct inhibitory effect of DHEA on glucocorticoid (re-)synthesis in adipose tissue:

Using differentiated 3T3-L1 adipocytes, we demonstrated that DHEA inhibited 11β-HSD1 activity at a concentration of 1 μM within 10 min. Inhibition was also observed in a cell-free system comprised of microsomes prepared from rat adipose tissue and NADPH, a coenzyme of 11β-HSD1. A kinetic study revealed that DHEA acted as a non-competitive inhibitor of 11β-HSD1. Further, DHEA did not inhibit 11β-HSD type 2, which inactivates cortisol or corticosterone in tissues involved in water and electrolyte metabolism, in rat kidney microsomes at a concentration <25 μM. Moreover, no conversion from DHEA to other sex steroid hormones or their precursors was observed under the present experimental conditions.

These are three significant observations. Firstly, the presence of DHEA inhibits the synthesis of cortisol via 11Beta-HSD1. Secondly, it does not prevent exogenous cortisol to be converted to the "inactive" cortisone via 11Beta-HSD2 and thirdly, the dreaded conversion into estrogen, testosterone or DHT does not take place. All this would make the naturally occurring hormone DHEA a perfect selective 11β-HSD1 inhibitor, of which Stewart et al. from the University of Birmingham write (Stewart. 2011):

Selective 11β-HSD1 inhibitors lower blood glucose, improve insulin sensitivity and cause weight loss in animal models. Biomarkers have been validated to confirm target inhibition in primate and human studies. Recent clinical trials show reduction in HbA1c and blood pressure in obese patients with diabetes mellitus who have failed on metformin therapy. Potentially the therapy offers a ‘magic bullet’ for patients with Metabolic syndrome with reduced blood glucose accompanying improved insulin sensitivity, lower lipids and blood pressure and reversal of hepatic steatosis secondary to reduced autocrine generation of cortisol in liver, adipose tissue, pancreas and muscle. Liabilities include activation of the HPA axis secondary to increased cortisol clearance with hyperandrogenism, though the extent and significance of this is debated.

One thing, though, before you now go about eradicating cortisol to zero. Your body needs a healthy level of cortisol to function. It goes hand in hand with thyroid hormone, helps you manage stress, perform in the gym and is even necessary to "burn" body fat. Again, moderation is key and you certainly want to know where you stand before you start tweaking your cortisol levels into the wrong direction.

A Relaxing, Cortisol Reducing, Testosterone Manipulating Cup of Roiboos Tea, Anyone? Plus: From Herpes, Over Liver-Toxicity to Cancer - Things Rooibos Can Do For You!

"Decallerate" your life - drink tea!?

I am starting to think that I may have totally underestimated Roiboos tea... I mean, tea without my beloved caffeine? That cannot be good for anything, can it? Well, it looks like it can!

After a couple of database searches, I did eventually have to realize that the most recent study by Schloms et al. is only the tip of an ice-, or rather "paper-berg" discussing various beneficial health effects of Aspalathus linearis infusions (aka Rooibos [/ˈrɔɪbɒs/], "the red bush" tea) that range from anti-viral to anti-cancer and pro-liver to pro-lung effects.

From South Africa to the Netherlands

In view of the fact that even I, as a German am more or less lucky to know what Rooibos is and you (mostly US and UK citizens) are only slowly catching up with my countrymen and our Western neighbors, the Dutch, as far as Rooibos imports and consumption is concerned, I just want to clarify that we are talking about a "popular tisane or herbal tea made from the stems and leaves of the fynbos plant, Aspalathus linearis, which is unique to the Western Cape region of South Africa" (Schloms. 2013).

What else can Rooibos do for you? Decreased incidence of herpex simplex + beneficial effects on other skin diseases (1.5l tea, orally; Shindo. 1991); liver protectant (Bosek. 2003); no inhibition of iron absorption (Hesseling. 1979; Breet. 2005; no ADHD?). Anti-cancer effects (Marnewick. 2005 ⇋ fermented = more effective; Sissing. 2008); antidiarrhoeal activity (Gilani. 2006); bronchodilator and antispasmodic (Khan. 2006); increased CYP3A activity (metabolizes caffeine, for example; Matsuda. 2007); anti-estrogenic effects in breast cancer ➙ reduced growth (Verhoog. 2007b; note: low estrogenic activity of its ow ➙ SERM)... there is more (mostly on anti-oxidant activities), but I think this should suffice.

Rooibos is sold as fermented and unfermented tea. While the latter has a higher anti-oxidant capacity, the former containing unique byproducts of the oxidation process. Contrary to the common perception these molecules are neither metabolic waste nor dangerous toxins, but can have a distinct set of beneficial metabolic effects of their own (Joubert. 2008).

The good thing: Unfermented Rooibos tea increases the testosterone to cortisol ratio

For the study at hand, Schloms et al. used unfermented Rooibos from the South African
Rooibos Council.  We can thus exclude any processing specific effects and simply assume that the results the scientists from the Stellenbosch University in South-Africa observed, when they administered the chloroform-methanol extract from the fresh tea leaves (1g of Rooibos leaves yielded 0.158 g extract) to their "subjects" - male Wistar rats.

The dosage the rodents received by oral gavage, was chosen to contain the rodent equivalent of the amount of soluble solids from one infusion with 15 g Rooibos leaves (six cups of fermented Rooibos per day). This means: If we discard inter-species differences, every serious Rooibos drinker should see changes in his (cortico-)steroid levels which resemble those you see in Figure 1:

Figure 1: Deoxycortisol (precursor), corticosterone (active), 11-dehydrocorticosterone (inactive corticosteroid) and testosterone levels after 10 days on rodent equivalent of six cups of Rooibos tea that was prepared with 15g of unfermented leaves; all values expressed relative to inter-group averages (Schloms. 2013)

Nice!? I'd agree, but I would also ask the one important question: How does this work? The answer is not exactly easy, but basically the arrows in Figure 1 give away parts of the answer, already. To understand what's going on, here we do yet still have to take a closer look at the actual production of cortisol in the andrenal gland and its subsequent metabolism:

"In the adrenal, the biosynthesis of glucocorticoids, min eralocorticoids, and adrenal androgens from the com mon precursor, cholesterol, is catalyzed by the cytochrome P450 (P450) enzymes and 3 -hydroxysteroid dehydrogenases (3 HSD), with cytochrome P450 11 -hydroxylase (CYP11B1) catalyzing the production of corticosterone (CORT) and cortisol from their respective precursors, deoxycorticosterone (DOC) and deoxycortisol." (Schloms. 2013)

Ok, of the hormones mentioned in this explanation you have both, cortisol and deoxycorticosterone in Figure 1. As you can see,...

• 

  Illustration 1: Interconversion of cortisol and cortisone as well as CORT and 11-DHC by 11 HSD-type-1 and type-2

  the consumption of the Rooibos tea lead to a significant reduction of DOC;
• the inactive CORT metabolite 11- dehydrocorticosterone (11-DHC), on the other hand did not change much;
• the latter would yet have been the case if the reduction in cortiosterone was a result of an increased metabolism of this rodent-specific corticosteroid

... which means that whatever the tea does, must block the production, not increase the deactivation of corticosteroids, and as a SuppVersity reader you probably already know how that works!? Right!

Rooibos tea is a 11 HSD1 inhibitor

In plain English you would probably say: Some of the active ingredients in Rooibos tea have the marvelous ability to block the enzyme that's responsible for the conversion of in-active to active corticosteroids.

Figure 2: In the corresponding 6-week (6 cups of tea per day) human study, none of the measured sex- nor corticosteroids changed significantly (Schloms. 2013)

The bad thing: This doesn't really work in human beings! For all the 7-keto lovers out there, this may sound awesome. It would after all mean that you could stop buying the overpriced DHEA-metabolite and start drinking some cheap Rooibos tea, unfortunately, Schloms et al. hid the results of a human study they conducted so cleverly in the abstract of their latest paper, that you one will easily overread that the 6-week intervention in which  24 women and 16 men between the ages of 30 and 60 years, with at least two or more risk factors for coronary heart disease (e.g. hypercholesterolemia, hypertension, or an increased BMI) consumed six cups of fermented Rooibos per day (15 g Rooibos leaves/subject) sucked, i.e. did not produce the desired results.

While there were significant decreases in the cortisone : cortisol (active : inactive corticosteroid) levels in both, men and women, there were no significant changes in cortisol, alone, testosterone, or the testosterone : cortisol ratio. With to the large inter-subject variations for testosterone, there is yet a chance that it worked for some, but not all male study participants.

 
References:

• Bosek, P., and M. Nakano. "Hepatoprotective effect of rooibos tea (Aspalathus linearis) on CCl4-induced liver damage in rats." Physiol. Res 52 (2003): 461-466.
• Breet, P., Kruger, H. S., Jerling, J. C., & Oosthuizen, W. (2005). Actions of black tea and Rooibos on iron status of primary school children. Nutrition Research, 25(11), 983-994.
• Gilani, Anwarul Hassan, et al. "Antispasmodic Effects of Rooibos Tea (Aspalathus linearis) is Mediated Predominantly through K+‐Channel Activation." Basic & clinical pharmacology & toxicology 99.5 (2006): 365-373.
• Hesseling, P. B., J. F. Klopper, and P. D. R. Van Heerden. "The effect of rooibos tea on iron absorption." (1979).
• Joubert, E., et al. "South African herbal teas: Aspalathus linearis, Cyclopia spp. and Athrixia phylicoides—A review." Journal of Ethnopharmacology 119.3 (2008): 376-412.
• Khan, Arif-ullah. "Selective bronchodilatory effect of Rooibos tea (Aspalathus linearis) and its flavonoid, chrysoeriol." European journal of nutrition 45.8 (2006): 463-469.
• Marnewick, Jeanine, et al. "Inhibition of tumour promotion in mouse skin by extracts of rooibos (< i> Aspalathus linearis</i>) and honeybush (< i> Cyclopia intermedia</i>), unique South African herbal teas." Cancer Letters 224.2 (2005): 193-202.
• Matsuda, Kazuhiro, et al. "Effects of continuous ingestion of herbal teas on intestinal CYP3A in the rat." Journal of pharmacological sciences 103.2 (2007): 214-221.
• Schloms, Lindie, et al. "Rooibos influences glucocorticoid levels and steroid ratios in vivo and in vitro: A natural approach in the management of stress and metabolic disorders?." Molecular nutrition & food research (2013).
• Shindo, Y., and K. Kato. "Effect of rooibos tea on some dermatological diseases." Proceedings of the international symposium on tea science. 1991.
• Sissing."Investigations into the cancer modulating properties of Aspalathus linearis (rooibos), Cyclopia intermedia (honeybush) and Sutherlandia frutescens (cancer bush) in oesophageal carcinogenesis." M.Sc. (Physiology) Thesis. University of the Western Cape, Bellville, South Africa (2008).
• Verhoog, N. J. D., E. Joubert, and Ann Louw. "Screening of four Cyclopia (honeybush) species for putative phyto-oestrogenic activity by oestrogen receptor binding assays." (2007).