New study of pine nuts leaves mystery of 'pine mouth' unsolved

Ali Reza Fardin-Kia, Sara M. Handy and Jeanne I. Rader note that more than 20,000 tons of pine nuts are produced each year worldwide. "Pine mouth," first reported in Belgium in 2000, is a bitter metallic taste that develops within one to two days of eating pine nuts and can last from one to two weeks. In 2009, the French Food Safety Administration reported a possible link between "pine mouth" and consumption of nuts of Pinus armandii, a pine species whose nuts are not traditionally eaten by humans. Researchers have identified certain fatty acids whose levels vary among pine species, making them a potentially useful tool for telling different species apart. To determine the source of pine nuts sold in the U.S., the first such effort, they measured the ratio of these compounds to the overall amount of fatty acids in the nuts.

Using fatty acid composition and a fatty acid diagnostic index (DI) along with DNA analysis, they found that most pine nuts sold in the U.S. are mixtures of nuts from different pine species, including Pinus armandii. They report that combining the fatty acid DI and DNA analysis is a useful way to determine which samples of pine nuts are mixtures of nuts from several species, but that this information itself may not definitively predict which pine nuts may cause "pine mouth." Its cause remains a mystery.

More information: Characterization of Pine Nuts in the U.S. Market, Including Those Associated with “Pine Mouth”, by GC-FID, J. Agric. Food Chem., 2012, 60 (10), pp 2701–2711. DOI: 10.1021/jf205188m

Abstract
Taste disturbances following consumption of pine nuts, referred to as “pine mouth”, have been reported by consumers in the United States and Europe. Nuts of Pinus armandii have been associated with pine mouth, and a diagnostic index (DI) measuring the content of ?5-unsaturated fatty acids relative to that of their fatty acid precursors has been proposed for identifying nuts from this species. A 100 m SLB-IL 111 GC column was used to improve fatty acid separations, and 45 pine nut samples were analyzed, including pine mouth-associated samples. This study examined the use of a DI for the identification of mixtures of pine nut species and showed the limitation of morphological characteristics for species identification. DI values for many commercial samples did not match those of known reference species, indicating that the majority of pine nuts collected in the U.S. market, including those associated with pine mouth, are mixtures of nuts from different Pinus species.

Provided by American Chemical Society (news : web)

The unsolved mystery of kava toxicity

 A major new review of scientific knowledge on kava — a plant used to make dietary supplements and a trendy drink with calming effects — has left unsolved the mystery of why Pacific Island people can consume it safely, while people in the United States, Europe, and other Western cultures sometimes experience toxic effects. The article appears in ACS' journal Chemical Research in Toxicology.

Line Olsen and colleagues point out that for centuries, people of the Pacific Islands have safely consumed a beverage made from crushed kava roots. Kava'scalming effects made it popular in Western cultures in the 1990s, when people also began to use a herbal supplement for the treatment of anxiety, emotional stress and sleep problems. But in 2001, reports of liver damage among Westerners who took kava supplements gained widespread attention. Many Western countries, including the United States, the United Kingdom, and Canada, ban or regulate the sale of kava products. To determine why kava is toxic to some people but not to others, the researchers sifted through the scientific studies published on the topic.

Their review of 85 scientific studies on kava toxicity found no consensus on kava toxicity, despite several theories that have emerged over the years. Culprits include methods for preparing kava, the particular species of kava used, the possible toxicity of substances produced by the body when kava is digested and genetic differences among consumers. "To date, there remains no indisputable reason for the increased prevalence of kava-induced hepatotoxicity in Western countries," the researchers say.

More information: “Constituents in Kava Extracts Potentially Involved in Hepatotoxicity – A Review” Chem. Res. Toxicol., Article ASAP DOI: 10.1021/tx100412m

Abstract
Aqueous kava root preparations have been consumed in the South Pacific as an apparently safe ceremonial and cultural drink for centuries. However, several reports of hepatotoxicity have been linked to the consumption of kava extracts in Western countries, where mainly ethanolic or acetonic extracts are used. The mechanism of toxicity has not been established, although several theories have been put forward. The composition of the major constituents, the kava lactones, varies according to preparation method and species of kava plant, and thus, the toxicity of the individual lactones has been tested in order to establish whether a single lactone or a certain composition of lactones may be responsible for the increased prevalence of kava-induced hepatotoxicity in Western countries. However, no such conclusion has been made on the basis of current data. Inhibition or induction of the major metabolizing enzymes, which might result in drug interactions, has also gained attention, but ambiguous results have been reported. On the basis of the chemical structures of kava constituents, the formation of reactive metabolites has also been suggested as an explanation of toxicity. Furthermore, skin rash is a side effect in kava consumers, which may be indicative of the formation of reactive metabolites and covalent binding to skin proteins leading to immune-mediated responses. Reactive metabolites of kava lactones have been identified in vitro as glutathione (GSH) conjugates and in vivo as mercapturates excreted in urine. Addition of GSH to kava extracts has been shown to reduce cytotoxicity in vitro, which suggests the presence of inherently reactive constituents. Only a few studies have investigated the toxicity of the minor constituents present in kava extract, such as pipermethystine and the flavokavains, where some have been shown to display higher in vitro cytotoxicity than the lactones. To date, there remains no indisputable reason for the increased prevalence of kava-induced hepatotoxicity in Western countries.

Provided by American Chemical Society (news : web)

The unsolved mystery of kava toxicity

A major new review of scientific knowledge on kava — a plant used to make dietary supplements and a trendy drink with calming effects — has left unsolved the mystery of why Pacific Island people can consume it safely, while people in the United States, Europe, and other Western cultures sometimes experience toxic effects. The article appears in ACS' journal Chemical Research in Toxicology.

Line Olsen and colleagues point out that for centuries, people of the Pacific Islands have safely consumed a beverage made from crushed kava roots. Kava'scalming effects made it popular in Western cultures in the 1990s, when people also began to use a herbal supplement for the treatment of anxiety, emotional stress and sleep problems. But in 2001, reports of liver damage among Westerners who took kava supplements gained widespread attention. Many Western countries, including the United States, the United Kingdom, and Canada, ban or regulate the sale of kava products. To determine why kava is toxic to some people but not to others, the researchers sifted through the scientific studies published on the topic.

Their review of 85 scientific studies on kava toxicity found no consensus on kava toxicity, despite several theories that have emerged over the years. Culprits include methods for preparing kava, the particular species of kava used, the possible toxicity of substances produced by the body when kava is digested and genetic differences among consumers. "To date, there remains no indisputable reason for the increased prevalence of kava-induced hepatotoxicity in Western countries," the researchers say.