The DNP effect of anacardic acid in cashew nuts

The most effective and also most dangerous slimming aid available on the black market is dinitrophenol, or DNP for short [structural formula on the right]. Fifteen years ago researchers at Tohoku University in Japan discovered that cashew nuts contain substances that work in the same way as the illegal DNP.

DNP deregulates cells at a fundamental level, causing the mitochondria – the cellular power stations – to stop converting nutrients into energy providing molecules of ATP. Uncoupling oxidative phosphorylation is the term used for this effect.

As a result cells are not as thrifty in their energy expenditure. They convert much larger quantities of nutrients into energy, but a relatively large proportion is released as heat. At the same time the mitochondria produce unusually large quantities of free radicals, which can cause damage to some structures. In the period between the two world wars DNP was a popular slimming aid all over the world, but governments put a stop to this when users started to turn blind.

Nevertheless DNP continued to circulate after the Second World War. Every so often there was a guru who rediscovered DNP, trumpeted its slimming effects far and wide, thereby helping several careless or unfortunate users to an early death.

Some of the gurus were more creative and discovered a substance that had the same effect as DNP. An example of this is usnic acid. At the start of this century usnic acid was found in a couple of slimming supplements, which caused so much damage in some users at least that they had to have a liver transplant. And anacardic acid is also a naturally occurring substance that might also turn up soon in a slimming aid.

In 2000 Masaaki Toyomizu published a study in which he performed experiments with anacardic acids from a cashew nut product. One of the compounds was 6-pentadecylsylic acid [structural formula shown below] [1].


Toyomizu extracted mitochondria from rats’ liver cells and exposed some of these to DNP and others to 6-pentadecylsylic acid. Toyomizu discovered that both substances had similar effects.

They both reduced the ADP:oxygen ratio and the respiratory control ratio [RCR]. Both of them also brought the mitochondrial material into the state 4 phase as molecular biologists call is.

To cut a long and complicated story short: as a result of both compounds the mitochondria started to burn more energy, but became less efficient in how they used the energy. They were less capable of storing it in the form of energy phosphates.



The Japanese were enthusiastic about their discovery, as they believed they’d discovered a new, natural slimming aid.

“Certain uncoupling agents were once used to treat obesity by lowering the efficiency of ATP production”, they wrote. “These agents proved to be extremely toxic, however and their use has long since been discontinued. […] Note that anacardic acids are one of the natural products found not only in the cashew nut shell oil but also the nut and fruit juice, which have long been consumed by many people as both food and drink.”

Substances that in they natural food form are harmless and may even be healthy can turn into a pretty risky substance when isolated. Perhaps we should just leave anacardic acids in cashew nuts and cashew apple juice.

Uncoupling effect of anacardic acids from cashew nut shell oil on oxidative phosphorylation of rat liver mitochondria.

Toyomizu M1, Okamoto K, Ishibashi T, Chen Z, Nakatsu T.


Anacardic acids are one of natural products found in not only the cashew nut shell oil but also the nut and fruit juice. The present study was conducted to investigate the uncoupling effect of anacardic acids on oxidative phosphorylation of rat liver mitochondria using succinate (plus rotenone) as a substrate. Four anacardic acids with C15:0, C15:1, C15:2 or C15:3 as an alkyl side chain exhibited uncoupling effects similar to the classical uncoupler, 2,4-dinitrophenol on ADP/O ratio, state 4 and respiratory control ratio (RCR). Anacardic acid with C15:1 side chain was most effective for uncoupling of these compounds. Salicylic acid, which has no alkyl side chain, exhibited a very weak uncoupling effect on oxidative phosphorylation. When the carboxyl group in anacardic acids was lost converting them to the corresponding cardanols, uncoupling activity dramatically decreased regardless of the number of double bonds in the long alkyl chain. These results suggest that the C15 alkyl side chain as well as the carboxyl group may play an important role in assisting the uncoupling activity of anacardic acids in liver mitochondria of animals. This study provides the first evidence of an uncoupling effect of anacardic acids on liver mitochondria

PMID: 10665998 [PubMed – indexed for MEDLINE]