by Densie Webb
Spices are used by civilizations worldwide for both flavoring and healing.1 Phenolics, especially flavonoids, are thought to be essential bioactive compounds in spices' health benefits.2 Research demonstrates that several culinary spices possess disease-preventing and antimicrobial properties when taken in large quantities.
Commercial saffron is produced from dried pistils of Crocus sativus, a member of the large family Iridaceae, and is cultivated in Azerbaijan, France, Greece, India, Iran, Italy, Spain, China, Israel, Morocco, Turkey, Egypt and Mexico.3 Saffron is the world's most expensive spice, primarily because it is still cultivated and harvested by hand, as it has been for thousands of years.3,4
Saffron is studied for its potential as an anticancer agent, memory enhancer, depression treatment and premenstrual syndrome reliever. Both laboratory and animal studies indicate that saffron and its pharmacologically active components possess anticarcinogenic and antitumor activities.3 In mice, saffron extract (200 mg per kg of body weight) inhibits the growth of tumors and increases life span two- to three-fold.5 One study found that crocin, a carotenoid isolated from saffron, increased survival time and decreased tumor growth in female rats, but had no effect on male rats; this suggests hormones may influence saffron's therapeutic effectiveness.6 The scarcity and expense of obtaining large quantities of saffron may impede its use in cancer treatment.3
Studies have tested the effectiveness of saffron extract in the treatment of depression and compared it with commonly used antidepressants (e.g., imipramine and fluoxetine). In one study, 30 people diagnosed with mild to moderate depression were given either 30 mg per day of saffron extract or 100 mg per day of imipramine for six weeks.7 Both groups improved equally. In a similar study, the same dose of saffron was compared with fluoxetine for six weeks. Again, both groups improved.8 Researchers from both studies concluded that saffron may be beneficial in treating depression. Crocin and safranal, two major components of saffron, may inhibit the re-uptake of the neurotransmittters dopamine, norepinephrine and serotonin,8 which are widely believed to improve mood.
Similarly, 30 mg per day of saffron extract relieved PMS symptoms in a double-blind, randomized, placebo-controlled trial over the course of two menstrual cycles. PMS symptoms were measured using the Hamilton Depression Rating Scale. A responder was defined as a woman showing 50 percent reduction in severity of symptoms. Sixty percent of the 25 women in the saffron group were responders, compared with 4 percent of the 25 women in the placebo group.9
The ancient Sumerians and Egyptians used Thymus vulgaris as a medicine and to embalm the dead.10 The ancient Romans used thyme to flavor cheese and alcoholic beverages, and they bathed in it to "provide vigor."10 Thyme is the most popular medicinal plant in Morocco and has been used in traditional medicine for thousands of years in African and European countries.11,12
Thyme is an antimicrobial, antifungal, antitussive, spasmolyitc and antioxidant.12,13 The essential oil derived from thyme is a mixture of monoterpenes, which are nonnutritive dietary compounds believed to have anticancer activity; one of the main monoterpenes is thymol, which has anti-inflammatory, immunomodulating, antioxidant, antibacterial, antifungal and free-radical-scavenging properties.14 Thymol makes up almost 49 percent of the total essential oil of thyme.15
Traditionally, thyme has been used as an expectorant and cough suppressant, and as an antiseptic or antimicrobial.16 In vitro studies show that a water-soluble extract of thyme is effective against Helicobacter pylori, the bacteria that causes most stomach ulcers.17,18 Recently, researchers observed that the essential oil of thyme prevented chemotherapy-resistant ovarian tumor cells from multiplying.12 In addition, laboratory studies found that thyme's phenolic compounds thymol and carvacrol, as well as thyme extracts, inhibited DNA damage in human white blood cells.19
Thyme oil and thymol improve the antioxidant status of the aging rat brain. Thyme oil and thymol may increase the concentrations of the omega-3 fatty acid docosahexaenoic acid. DHA is important for the proper growth and functioning of nervous tissue and may help protect against oxidative stress in the brain.15,20
Germany's Commission E approves thyme as a treatment for coughs and upper respiratory tract congestion and also for symptoms of bronchitis and whooping cough.21 However, there are no well-defined, controlled clinical trials for the use of thyme to treat these diseases.10,13 Despite a lack of controlled clinical evidence, thyme also has been used as a treatment for fingernail and toenail fungus.10
Thyme is safe in food and for limited medicinal use. However, it should never be used orally or in undiluted form.10 Controlled clinical trials for thyme's traditional medicinal uses are still needed.
Sage is a perennial shrub, native to the Mediterranean rim, especially around the Adriatic Sea; it is cultivated in Albania, Turkey, Greece, Italy, France, the United Kingdom and the U.S.22 Sage tea is the most common form of sage consumed by humans.23 The leaves from Salvia officinalis are reported to prevent the growth of bacteria, fungi and viruses, and also have cholinesterase-inhibiting properties, which may improve mood.24,25 Sage-leaf extracts exhibit strong antioxidant activity, probably due to phenolic constituents such as carnosol and rosmarinic acid.26 Commission E has approved the internal use of sage leaf for stomach upset and excessive perspiration and external use for inflammation of the mucus membranes of the nose and throat.22 It has also traditionally been used to suppress lactation in nursing mothers.27
Sage has been found to improve mood and cognition. In a double-blind, placebo-controlled crossover study, 30 healthy young men and women were given either 300 mg or 600 mg of dried sage leaf or placebo on three separate days at seven-day intervals. A single 600 mg dose of sage improved mood and cognitive performance.25 Sage's ability to inhibit acetylcholinesterase, the enzyme that breaks down the neurotransmitter acetylcholine, could explain the effects. Patients with dementia and depressed mood have reduced levels of acteylcholine, a chemical that carries messages in the brain. Inhibiting acetylcholinesterase could help increase acetylcholine levels.
Sage also has potential to treat Alzheimer's disease and dementia. In a randomized, double-blind, placebo-controlled study, 42 patients age 65 to 80, diagnosed with mild to moderate dementia and probable Alzheimer's disease, were given 60 drops per day of sage extract (1 kg of dried leaf to 1 liter of alcohol) or a placebo for four months.28 The sage extract produced a significantly better outcome on cognitive function tests than placebo. A 2008 study found memory-enhancing effects of a single dose of sage extract at 333 mg a day in 20 older adults, whose average age was 73.29 In vitro studies of rat brain cells suggest rosmarinic acid is one of the components of sage responsible, at least in part, for sage's neuroprotective effects.30
Sage also may help decrease blood glucose and prevent type 2 diabetes. Sage tea lowered blood-glucose levels in healthy rats given the tea in place of water for 14 days, but not in diabetic rats. The effects were similar to Metformin, a medication commonly prescribed for people with type 2 diabetes.23 In another experiment, both sage oil and sage extract were tested in diabetic rats. Sage extract decreased serum glucose in the rats within three hours of dosing, but the sage oil had no effect, suggesting that the active compound(s) are water-soluble and not found in the oil.24
The amount of sage leaf consumed as a culinary herb in foods is not hazardous, but larger amounts are toxic due to the presence of thujones and camphor in the essential oil. Neither ethanolic extracts nor the essential oil from sage leaf have shown mutagenic potential.26
Ginger, or Zingiber officinale, is a large tuberous perennial plant native to southern Asia and now cultivated extensively in almost all tropical and subtropical countries,31 though China and India are the world's leading producers of ginger.31 Ginger's medicinal use, which was recorded in early Sanskrit and Chinese texts, may date back 2,500 years.31 In Asian medical practices, dried ginger has been used to treat stomachache, diarrhea and nausea.31 Ginger is approved in the Commission E monographs as a component of anti-emetic stomach medicines. In Germany, Switzerland, Austria and Finland, a standardized extract of ginger is approved as a nonprescription medicine to prevent motion sickness.31
The mechanism underlying ginger's anti-emetic activity is unclear, but its aromatic properties, as well as its ability to relax muscles and reduce flatulence, suggest it has direct effects on the gastrointestinal tract. Ginger contains more than 400 chemicals. However, only a few—mainly gingerols, shogaols and paradols—have been evaluated for their pharmacological properties.32 Studies suggest that short-term use of ginger can safely relieve pregnancy-related nausea and vomiting.33 Though the Commission E monograph on ginger does not recommend it for morning sickness, reviews of the literature conclude that ginger is an effective, low-risk treatment for these symptoms, compared with placebo.34,35 The typical dose used in the studies reviewed was 1,000 mg per day. This dose effectively relieved nausea, even among women with severe nausea and vomiting leading to dehydration. Studies have also found ginger to be an effective treatment for nausea resulting from motion sickness (1 g to 2 g per day) and surgery (500 mg to 1,000 mg per day). 36,37 One study in dogs found that doses of 100 mg, 200 mg and 500 mg per kg of body weight effectively reversed the delay in gastric emptying caused by chemotherapy, which can cause nausea.38
No side effects have been observed in pregnant women taking ginger at the 1,000 mg-per-day dose. However, researchers express concern about the lack of consistency in levels of active ingredients and dosages, or serving sizes, among commercially available ginger-root powder supplements.39
This gold-colored spice is related to ginger and is the powdered roots and rhizome of the plant Curcuma longa.40 It is used in India and China for medicinal purposes, for the preservation of food and as a yellow dye for fabrics. Turmeric is one of the primary ingredients in curry. Curcumin, the compound that gives turmeric its yellow color and is believed to be the biologically active component of the spice, was first isolated almost two centuries ago.40,41
The Agricultural Research Service of the U.S. Department of Agriculture lists 78 biological activities associated with curcumin, from anti-HIV actions to antiulcerogenic actions.40 Most research with curcumin has been done in animals and in laboratory cell cultures. Substantial laboratory data indicate that curcumin has antioxidant, anti-inflammatory and anti-amyloid activity (i.e., it appears to prevent aggregation of beta-amyloids, believed to play a pivotal role in the development of Alzheimer's).42 Test-tube and animal studies demonstrate that curcumin exhibits significant anticancer activity.
Though inconclusive, studies in humans also suggest that turmeric consumption may reduce the risk
of some forms of cancer and render other protective biological effects in humans.44 A phase 1 clinical trial evaluated the effects of curcumin on people who had one of five high-risk conditions for several kinds of cancer. Researchers gradually increased doses of curcumin from 500 mg to 8,000 mg per day.45 Biopsies of precancerous lesions were performed immediately before and three months after starting curcumin treatment. Histologic improvement of the precancerous lesions was observed in five of the 19 patients taking curcumin.
Curcumin shows anti-inflammatory activity in human and laboratory studies.46 Recent studies show that curcumin also inhibits autoimmune diseases, such as rheumatoid arthritis, by regulating inflammatory cytokines, immune cells that signal other immune cells to act.47 A study of diabetic rats in which the animals were given 15 mg and 30 mg per kg of body weight of curcumin or no treatment for six weeks revealed that renal dysfunction and oxidative stress decreased in the rats receiving the curcumin when compared with the control group.48
Preliminary findings from a study with a group of elderly Asian men and women suggest eating curry more than once a month, but less than once a week, results in better cognitive function than in those consuming less. Cognitive function was assessed using the Mini-Mental State Examination, which measures memory, attention, language, praxis and visuospatial ability.49 However, a study of the curcumin content of turmeric and curry powders found that while the highest curcumin concentration of pure turmeric powder was 3.14 percent by weight, curry powder had a relatively small amount of curcumin, and the variability in content was great.41
Several common culinary spices have beneficial health effects when consumed in large quantities. Most of these spices exhibit some degree of antioxidant, anti-inflammatory, anticancer and antimicrobial activities. Some researchers suggest that future dietary guidelines should include more explicit recommendations about spices' place in a healthful diet.51 Most studies, however, have found beneficial effects from much larger amounts of spices than can be obtained from the diet.
Densie Webb, Ph.D., R.D., is a freelance writer and industry consultant based in Austin, Texas.
Natural Foods Merchandiser volume XXVIII/number 10/p. 108,110