Não bastasse não funcionar para o tratamento da ARTROSE DE JOELHO, a CARTILAGEM DE TUBARÃO pode conter uma toxina causadora de sérios problemas neurológicos, segundo estudo de cientistas da Universidade de Miami. Leia a reportagem publicada do jornal New York Times:


Barbara Walton/ New York Times, March 8th, 2012

Shark cartilage, which has been hyped as a cancer preventive and joint-health supplement, may contain a neurotoxin that has been linked with Alzheimer’s and Lou Gehrig’s disease.

CARTILAGEM-TUBARÃOScientists at the University of Miami analyzed cartilage samples collected from seven species of sharks off the coast of Florida. The specimens all contained high levels of a compound called beta-methylamino-L-alanine, or BMAA, which has been linked to the development of neurodegenerative diseases. Sharks accumulate the compound because of their status at the top of the oceanic food chain, consuming fish and other sea creatures that feed on BMAA-containing algae. The small tissue samples were obtained from sharks that were caught, tagged and released for tracking research, and no sharks were harmed for the study.

The findings are important because of the growing popularity of supplements that contain cartilage from shark fins. The products are widely sold and remain popular with consumers who view them as cancer fighters or as a remedy for joint and bone problems. The notion that shark cartilage can prevent cancer grew largely from the popularity of the 1992 book “Sharks Don’t Get Cancer.”

Although a number of studies have discredited shark cartilage as a cancer fighter, supplement makers have nonetheless made bold claims. In 2000, two supplement makers settled a federal suit as a result of hyping shark cartilage and paid restitution to customers.

In 2011, Americans spent about $3 million on shark cartilage supplements, a decline of about 15 percent from the previous year, according to the Nutrition Business Journal, a market research firm. Because shark cartilage supplements are “broadly connected to cancer prevention,” many consumers may wrongly assume that they can prevent or treat cancer, said Carlotta Mast, the editor in chief of NewHope360.com, which is owned by the parent company of the nutrition business journal.

Although the Miami scientists didn’t examine shark cartilage supplements directly, their findings add further cause for concern about the popularity of shark fin supplements. In the study, published in the journal Marine Drugs, the researchers found levels of BMAA ranging from 144 to 1,836 nanograms per milligram of cartilage in seven shark species, including hammerhead, blacknose, nurse and bull sharks. The toxin initially is produced by bacteria in large algae blooms that are brought on by agricultural runoff and sewage pollution.

CARTILAGEM DE TUBARÃOEarlier studies have suggested that BMAA may be common in the brains of people with degenerative diseases. One in 2009, for example, found that brain samplesfrom people who died of Alzheimer’s or Lou Gehrig’s disease had BMAA levels as high as 256 ng/mg. The brains of control subjects who died of other causes had only trace amounts or none at all. While BMAA has never been definitively cited as a cause of degenerative diseases in humans, some scientists hypothesize that it may be a contributing factor.

An amino acid produced mainly by aquatic bacteria, BMAA is harmful to neurons and produces muscle atrophy and nerve degeneration in primates. It first came to light as a neurotoxin when researchers cited it as a possible cause of unusually high rates of neurodegenerative disease among the Chamorro people of Guam, who get high amounts of BMAA in their diets.

Whether the substance can affect people who eat shark or take supplements made from their cartilage is unclear, but consumers may want to be cautious, said Dr. Deborah Mash, an author of the new study and a professor of neurology and pharmacology at the University of Miami Miller School of Medicine.

“We don’t want to scare people,” she said. “This is a first, and it needs to be replicated. We need to look at a wide array of shark products and fins.”

Sharks are also known to accumulate high levels of chemical pollutants and heavy metals like mercury and cadmium. At least 26 million sharks are killed each year to support the high demand for fins used in supplements and in shark fin soup, a delicacy served in restaurants throughout Asia. Environmentalists say the practice is contributing to steep declines in shark populations worldwide.