Diet Herbs: Schisandra Shrub, Senna, Spirulina, Uva Ursi And Yellow Dock


This herb comes from the fruit of the schisandra shrub, cultivated in China.

Schisandra is popular among herbalists as a liver protector. The herb is also used to treat colds, urinary incontinence, and allergies. It is unclear why schisandra is an ingredient in natural weight-loss supplements, since it has no effect on fat loss, nor is it a diuretic.

Schisandra is widely used in China, but very little information is available on its safety or effectiveness.


Senna is derived from the leaves of a shrub grown in India and is the active ingredient in several over-the-counter laxatives.

Senna is a strong laxative. It stimulates contractions of the colon to relieve constipation.

Side effects include severe cramps, violent diarrhea, dehydration, and electrolyte imbalance. Some dieter’s teas contain senna. It may produce a temporary loss of water weight, but it is neither effective nor safe if used as a weight-loss agent. Long-term use can lead to laxative dependence.


Also known as blue-green algae, spirulina has been a popular supplement for years, thanks to its “superfood” reputation. Nutritionally, spirulina is a treasure trove of health-giving nutrients: beta carotene, B-vitamins, magnesium, and zinc.

Spirulina has been touted as a curative for a range of conditions, including diabetes, liver disease, ulcers, and hair loss. But claims are largely without merit.

Spirulina has also been hailed as a weight-loss agent because it supposedly suppresses the appetite by increasing levels of the amino acid phenylalanine. In a Japanese study, diabetic patients were given twenty-one spirulina tablets a day, and within weeks, their symptoms improved, along with significant weight loss. Theoretically, the nutrient-packed spirulina reduced food cravings, which led to weight loss. However, more medical evidence is needed to verify whether spirulina affects appetite in any way.

There is really no harm in supplementing with spirulina. It’s an expensive way to obtain nutrients you can get from food, however. Also, if grown in polluted water, spirulina may contain harmful microorganisms. High levels of mercury and other toxic metals have been detected in some batches.

Uva Ursi

This herb is derived from the leaves of the bearberry, an evergreen plant.

A mild diuretic, uva ursi’s active ingredients are ursolic acid and isoquercetin, two natural chemicals that increase urine output. Other compounds in uva ursi help prevent bacteria from anchoring to the uretha. Thus, the herb may be helpful in treating a mild urinary tract infection. But don’t use it with cranberry juice or other acidic juices. They cancel out uva ursi’s anti-bacterial effect.

Although considered relatively safe, uva ursi tends to turn urine green. If you have a sensitive stomach, this herb can cause nausea and vomiting. The small amounts of uva ursi used in natural diet products are generally harmless, however.

Yellow Dock

The leaves and roots of yellow dock are used in herbal preparations. As a food, it has been used in salads.

This herb is a laxative known for its stimulating action on the gastrointestinal tract. It has been recommended for treating occasional constipation experienced by dieters after altering their eating habits. Still, that’s no reason to supplement with yellow dock. Eating a high-fiber diet and drinking plenty of fluids will usually correct such temporary constipation.

Yellow dock is considered slightly dangerous. Side effects include diarrhea, nausea, vomiting, and skin eruptions.

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