book review

Rational Phytotherapy
by V. Schulz, R. Hänsel, M. Blumenthal, and V.E. Tyler
Reviewed by T.J. Nelson

any people think that phytotherapeutics, known in the USA as herbal supplements, are safer than conventional drugs. And often that is true: the incidence of adverse effects with St. John's Wort in treating depression, say the authors, is only 2.5%, compared with 33% for SSRIs, despite similar efficacy.

But others are not so safe. Feverfew, a herb used for migraines, can cause hemorrhage. Chamomile is even worse. I tried chamomile tea one time. I had to drink two cups of coffee to keep from falling asleep. Awful stuff!

Rational Phytotherapy is a translation of the 4th edition of a German book. The latest reference is from 2003. That's not a big problem, since not much has changed in a while in this field. It's also packed with typos, but they don't affect the accuracy. There are many bar graphs and color photos of the relevant plants.

Much of the focus is on pharmacology and pharmacognosy. It discusses extraction, dosage, stability, concoction, and excipients. But there are lots of interesting facts as well:

• The Egyptians fed their slaves garlic during the construction of the pyramids to ward off febrile illnesses. It was one of the things the Israelites missed after they left.
• Menthol works by stimulating the coldness receptors in the nose, but it can cause fatal respiratory arrest in babies.
• Lovastatin, the anticholesterol drug, has been used in China since 800 A.D. in the Tang dynasty. It comes from red yeast rice, which is a combination of fungus growing on rice that contains monascolin K, aka lovastatin.*
• Linseeds contain small amounts of cyanide, produced by hydrolysis of linamarin by the plant enzyme linamarase. The levels of cyanide are lower than in bitter almonds.

The authors say that a Ginkgo tree was the first green thing that sprouted in Hiroshima after the war. Its survival was attributed to its high antioxidant levels, which also made it a candidate for Alzheimer's dementia and tinnitus. The Alzheimer work petered out, but many still claim that rutin and flavonoids such as quercetin which are abundant in Ginkgo biloba are effective against tinnitus due to their vasodilatory effect.

And that's the state of herbal science today: a twilight zone between popular anecdotes and molecular medicine. This is reflected in the presentation. There are no biosynthetic pathways, no details on purification or analysis, almost no chemical structures, and the dosing, pharmacokinetics, and mechanisms are vague. It's oriented toward pharmacists who deal with herbal supplements; in places it reads like an Adele Davis book, which makes it readable by laymen. For professionals there are many references, though most are in German.

Thousands of natural products are out there waiting to be discovered. But before we test them for human diseases, we must understand how the drug works mechanistically and know what causes the disease. Otherwise, it's hit or miss. That's one reason most of the drugs proposed for degenerative diseases like Alzheimer's have failed, and why they will continue to fail until somebody discovers the cause of the disease. Testing a product without a convincing mechanism of action is a waste of resources. I've seen it happen.

For liver diseases, the authors say that silymarin, the active principle from milk thistle fruits, induces liver regeneration. They make it sound almost miraculous. In one study, they say, survival rates were increased almost two-fold in patients with hepatic cirrhosis.

Later chapters give useful concoctions for dyspepsia, liver diseases, urinary tract infections, and benign prostatic hyperplasia (for which they recommend saw palmetto). There are also chapters on herbal treatments for atherosclerosis, sleep disturbances, arterial and venous insufficiency, gynecological diseases, respiratory infections, rheumatism, pain, joint problems, irritable bowel syndrome, diarrhea, and constipation.

These are all diseases of aging. I plan to hang on to this book for the time, not so far in the future, when all I have to do is lie around by the pool in a loud shirt, Bermuda shorts and golf shoes, sip on strawberry daiquiris, and complain to anyone who will listen about my prostate.

* According to Chen and Chen (Chinese Medical Herbology and Pharmacology p. 528) it is Hong Qu ( 紅麴 ), a concoction used for indigestion and spleen deficiency. The eponymous red color appears after it's fermented. Chen and Chen say Hong Qu is more potent than lovastatin alone.