Scientific Name(s): Simmondsia californica Nutall., Simmondsia chinensis (Link) Schneider.
Common Name(s): Jojoba, K-20W Jojoba
The toxicity of the constituent simmondsin in jojoba seed meal and some oil components limits the likelihood of clinical applications. Jojoba oil is commonly used in dermatological preparations.
There is no clinical evidence to guide dosage of jojoba or its oil; it is primarily used as a vehicle for oxidation-sensitive substances in ointments.
Although absolute contraindications have not been identified, jojoba should not be ingested by humans due to potential toxicity.
Information regarding safety and efficacy in pregnancy and lactation is lacking. Adverse toxicological studies in rodents and birds exist.
None well documented.
Case reports of contact dermatitis, confirmed by skin patch tests, exist for jojoba oil.
Constituents of jojoba are toxic. Studies demonstrate hematological toxicity, histological abnormalities, and other adverse effects.
S. chinensis is a desert shrub indigenous to Arizona, California, and northern Mexico that grows in a number of deserts worldwide. It is a woody, evergreen shrub with thick, leathery, bluish-green leaves and dark brown nut-like fruit. An equal number of male and female flowers are borne on separate plants. The plant can withstand extreme daily fluctuations of temperature and thrives in well-drained, desert soils and coarse mixtures of gravel and clay. The mature plant produces about 5 to 10 pounds of seeds, which range in size between the coffee bean and peanut. It is an important forage plant for desert bighorn sheep and mule deer.1, 2 A synonym is Simmondsia californica Nutall.
For a long time, American Indians and Mexicans have used jojoba oil as a hair conditioner/restorer and as a medicine, as well as in cooking and rituals. In the United States, jojoba is considered a viable cash crop for the southwestern Indians, and the Bureau of Indian Affairs has funded most of the studies in this area. With the banning of the sale of sperm whale oil in the 1970s, the cosmetic industry turned to jojoba oil for use in shampoos, moisturizers, sunscreens, and conditioners. It has further potential as an industrial lubricant because it does not break down under high temperature or pressure. A disadvantage to its use is its relatively high cost.2, 3, 4, 5
Jojoba seeds produce 50% to 55% by weight of a colorless, odorless oil or liquid wax. The wax is almost completely (97%) composed of straight chain monoesters of C-20 and C-22 acids and alcohols with 2 double bonds. The acids have been identified as a mixture of cis-11-eicosenoic (C-20) and cis-13-docosenoic (C-22, erucic) acids. The alcohols have been identified as mixtures of cis-11-eicosenol, cis-13-docosenol, and cis-15-tetracosenol (C-24). Also included are small quantities of sterols (less than 0.5% total of campesterol, stigmasterol, and sitosterol). Jojoba oil is essentially triglyceride free.6, 7, 8
Seed meal, the fraction left after the wax has been extracted, is protein-rich with albumins and globulins. The group of simmondsin compounds (10% to 20%) in this fraction, recognized as food-intake inhibitors, are removed before the meal can be used as animal feed. Processes for detoxification include chemical inactivation (ammonia), heat treatment, enzymatic hydrolysis, and solvent extraction. Analysis by gas chromatography and high-performance liquid chromatography have been described.5, 9, 10, 11
Uses and Pharmacology
The toxicity of the constituent simmondsin in jojoba seed meal and of some of the oil components limits the likelihood of clinical trials.
Topical administration of the refined wax to guinea pigs for 20 weeks resulted in no systemic effects. A reversible swelling accompanied by reduced skin flexibility and an increased sensitivity to shaving was observed. However, there were no histological changes in skin tissues. These effects were most likely due to an occlusive-like action created by the wax.12
Jojoba is most commonly recognized as an ingredient in cosmetics and other topical preparations at concentrations varying from 1% to 20%.13, 14 Limited clinical studies show skin hydrating effects of hydrolyzed jojoba esters similar in magnitude to glycerol.15, 16
In 2013, a 10-week randomized controlled field study in Madagascar documented rapid and significant improvements in tungiasis outcome measures in subjects treated twice daily with a coconut oil-based herbal repellent that includes jojoba oil and aloe vera. Tungiasis is a parasitic sand flea skin disease that can cause significant morbidity in many resource-poor tropical communities. At 2 weeks, the sand flea attack rate was zero and the intensity of infestation as well as the severity scores for acute and chronic tungiasis were significantly decreased. Within 10 weeks, the degree of tungiasis-associated morbidity approached zero.33
Anti-inflammatory effects have been demonstrated in experiments with induced rat paw edema, and in granulation models; these effects have also affected neutrophil activity.17
Jojoba exhibits antioxidant activity, probably related to the content of alpha-tocopherol found in the leaves.18
In a rabbit study, ingestion of jojoba oil as a 2% supplement to an atherogenic diet produced a 40% reduction of blood cholesterol, although the mechanism by which this occurred was not determined.19 Simmondsin is a recognized anorectic, affecting the satiety response, as well as causing a conditioned taste aversion.20, 21, 22 Jojoba seed meal has been used as animal feed once detoxified. The treated meal is nontoxic to mice, poultry, sheep, and cattle.23, 24
There is no clinical evidence to guide dosage of jojoba or its oil; it is primarily used as a vehicle for oxidation-sensitive substances in ointments.5
Pregnancy / Lactation
None well documented.
The oral median lethal dose of crude jojoba wax is more than 160 g/kg in mice.28 Subcutaneous injection of 1 mL/kg for 7 weeks in test animals resulted in no systemic effects, although some systemic accumulation was observed.12
In experiments in rats, jojoba meal as a feed showed no changes in liver, kidney, or spleen histology; however, reversible depression of red blood marrow cells was observed.29 Histological changes in the small intestine and increases in serum transaminases have also been reported in rodents.30
Jojoba oil is 14% erucic acid, a causative factor in myocardial fibrosis. Although no direct relationship has been established between this compound and jojoba toxicity in humans, jojoba should not be ingested in any form.19, 31
Limited experiments in rodents suggest effects of jojoba meal on the developing fetus related to decreased maternal food intake.25, 32 In female broiler chickens, jojoba meal decreased feed intake and controlled body weight; however, the birds were unable to produce eggs due to small oviducts. No effect on the ovaries or follicle development was observed.26
- Simmondsia californica Nutall
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