|
From The February 2001 Issue of Nutrition Science News
At the Counter
with Dan Lukaczer, N.D.
The Yam Cream Conundrum
Is there really progesterone in those wild yam creams? And if not, are the creams just a big hoax?
The answer is both simple and complex. The first part is simple: There is clearly no progesterone found in wild yam (Dioscorea spp.). Wild yam contains a phytochemical called diosgenin. When extracted from wild yam, diosgenin can be chemically changed in a laboratory to bioidentical human progesterone. In fact, much of the USP-grade progesterone used for hormone replacement therapy is formed by this process. However, using wild yam either orally or as a cream will not deliver progesterone because our bodies do not have the enzymes necessary for that conversion. So when companies try to sell yam cream as a source of progesterone, it is a scam.
But here's where it starts to get complex. Some companies add USP-grade progesterone to natural yam cream, enabling them to say they do have progesterone in their product—it's added to the yam extract. Under FDA guidelines, yam creams (or any creams) are allowed to add progesterone and be sold as a dietary supplement or cosmetic. However, such products must contain only 5 mg or less progesterone per ounce. If they contain more than 5mg/oz progesterone, they are considered drugs (21 CFR Sec.310.530) and therefore must be sold as prescription items.
There has been an explosion of information in the past 10 years—some anecdotal, some published research—suggesting natural progesterone applied as a cream and absorbed transdermally may help manage hormonal problems in premenstrual, perimenopausal, and postmenopausal women.1 If a yam cream states it contains progesterone, that may be true. However, the amount of progesterone is important, because to reap the effects of progesterone, 15-40 mg/day of this hormone is generally recommended—far greater than the amount found in an over-the-counter two-ounce bottle.
Citrus for Cancer
Can limonene be helpful for cancer prevention?
Limonene is what's called a monoterpene and is found most abundantly in the essential oils of citrus fruits and other plants. For example, D-limonene comprises more than 90 percent of the essential oil from orange peels (Citrus sinensis).2 Animal studies have shown monoterpenes in general have anti-tumor activity. The mechanism of action is not entirely clear, but certainly one aspect is their induction of detoxifying enzymes.3 Several clinical trials are currently under way in breast and prostate cancer treatment.4
Inside Broccoli
I've heard quite a bit about a broccoli extract called indole-3-carbinol (I3C). What is the difference between it and the other broccoli extract called diindolylmethane (DIM)?
To answer that question, a little biochemistry is in order. Indole-3-carbinol (I3C) is a secondary metabolite found in cruciferous vegetables such as broccoli, cauliflower, kale, cabbage and brussels sprouts. A secondary metabolite is one not found preformed in vegetables, but formed after an enzyme in the vegetable (myrosinase) is exposed to a phytochemcial in the vegetable (glucobrassicin). This can occur only when vegetable cells are crushed or eaten, and is referred to as enzymatic hydrolysis.
I3C, thus formed, is then broken down in the presence of acid (as in the acid environment of the stomach) to various by-products such as diindolylmethane (DIM), which are then absorbed.
Why is this important? Because I3C has been shown to inhibit cancer cells in animal cancer models of the mammary, liver, and lung.5-7 It is currently being evaluated in human clinical trials as a potential chemopreventive agent against breast and ovarian cancers.8
I3C appears to work by upregulating or modulating certain enzymes that improve the detoxification of various potential carcinogens—although it appears to be the breakdown products that have this effect rather than IC3 itself. Furthermore, it is not clear that DIM is the only breakdown product of importance.9
Certainly DIM by itself has an effect, but these other products may also be important for the overall cancer-inhibiting action. As most of the research to date has focused on I3C, it seems prudent at this time to use supplements containing I3C instead of DIM. Just make sure you take it with meals and have sufficient acidifying capacity in your stomach.
Dan Lukaczer, N.D., is director of clinical research at the Functional Medicine Research Center, a division of Metagenics Inc., in Gig Harbor, Wash.
References
1. Lee J. Use of Pro-Gest cream in postmenopausal women. Lancet 1998;352(9131):905.
2. Crowell P. Prevention and therapy of cancer of dietary monoterpenes. J Nutr 1999;129(3):775s-8s.
3. Elegbede J, et al. Effects of anticarcinogenic monoterpenes on phase II hepatic metabolizing enzymes. Carcinogenesis 1993;14(6):1221-3.
4. Vigushin D, et al. Phase I and pharmacokinetic study of D-limonene in patients with advanced cancer. Cancer Research Campaign Phase I/II Clinical Trials Committee. Cancer Chemother Pharmacol 1998;42(2):111-7.
5. Grubbs C, et al. Chemoprevention of chemically induced mammary carcinogenesis by indole-3-carbinol. Anticancer Res 1995;15:709-16.
6. Oganesian A, et al. Long term dietary indole-3-carbinol inhibits diethylnitrosamine-initiated hepatocarcinogenesis in the infant mouse model. Cancer Lett 1997;118:87-94.
7. Chung F, et al. Inhibition of tobacco-specific nitrosamine-induced lung tumorigenesis by compounds derived from cruciferous vegetables and green tea. Ann NY Acad Sci 1993;686:186-201.
8. Bradlow H, et al. Indole-3-carbinol, a novel approach to breast cancer prevention. Ann NY Acad Sci 1995;768:180-200.
9. Wortelboer H, et al. Acid reaction products of indole-3-carbinol and their effects on cytochrome P450 and Phase II enzymes in rat and monkey hepatocytes. Biochem Pharmac 1992;43(7):1439-47.
|
