As with anything else, many manufacturers are motivated by profit. A claim on 0.3% hypericin is no guarantee that you will actually get this amount. The Los Angeles Times commissioned a private laboratory to analyze several of the most popular brands of St. John's Wort in the US. The results were shocking. Three out of ten had less than 50% potency. Four had less than 90%. Sundown Herbals, a leading supplier of herbals in the US, had an abysmal 20% of the labeled potency. Why does this occur? Herbals aren't considered medications, and are not regulated as such.
Actually before I even read this article I found out the hard way that it is true. I had been taking a brand called Nature's Fingerprint (now called Herbal Plus Fingerprinted) from GNC with good success. I decided, however, that I would try out one of the less expensive alternatives. Big mistake! Within a few weeks I was very depressed. I went back to my regular brand and soon recovered. Although I'm sure there are other good brands out there, you won't catch me trying them. Not until they are more strictly regulated and I can be assured of their quality.
Once you have a good product, you may use the recommended dosage as a guideline. Just as with prescription medications, however, you will need to fine tune it, adjusting up or down until you get the dose that works best for you. You may even need to fine tune it from bottle to bottle if you are not using a brand that is standardized. I prefer using the pure powdered herb, rather than the standardized capsules or tinctures. When I switch to a new lot number, I find that I may need to adjust up or down one capsule.
As far as frequency of dosage, many products recommend taking it three times a day. This is not necessary. Simply combine the total amount for the day and take it as one dose. It works just fine this way and is much more convenient.
Safety During Pregnancy
This is a question very much on my mind right now, but there doesn't seem too that much data out there. The general consensus seems to be we just don't know so we're not going to recommend it. Peg Plumbo at Parent's Place provides the best answer I've seen. She states that while information about St. John's Wort during pregnancy is scant, there are a few case reports in The Journal of the American Medical Association of women taking it during their pregnancies. In one particular case, the woman case birth to a healthy baby, but had a low platelet count herself during the last trimester. The baby developed jaundice on it's fifth day, but was treated successfully. Ms. Plumbo further states that there is some evidence that St. John's Wort may cause uterine contractions in animals, thus predisposing a woman to pre-term labor.
My own opinion is that one should avoid antidepressants of any type during the first trimester. In the second and third trimester, if a woman becomes sufficiently depressed that she requires an antidepressant she should by all means take one. If a woman is too depressed to adequately take care of herself and the baby inside her, this may pose a greater risk to the baby than the drug itself. Certain antidepressants, such as Prozac, have been used widely enough by now that a picture of their relative safety is now developing. It would appear that St. John's Wort is also relatively safe, but sufficient data does not exist to say this with any certainty. Until more is known, women should opt for prescription antidepressants with known track records during their pregnancies.