In a 2006 article in Biological & Pharmaceutical Bulletin, Naganuma et.al. write that both turmeric and curcumin effect certain reactions in cultured cells that indicate the anti-cancer effects of turmeric and curcumin may at least be partly due to how they affect what is known as conjugation in the body.
Conjugation is a critical point
When your body ingests something, such as a drug or chemical, it undergoes various reactions in your body. It can have certain molecules added to it which help the body eliminate the drug or chemical via the urinary system, or it can be detoxified, or it can undergo a reaction which makes it dangerous to the body. The last kind of reaction can turn a pro-carcinogen into a carcinogen.
The scientific name for certain groups of these reactions is conjugation. Conjugation reactions which have been considered important in how procarcinogens are handled by the body include glucuronidation and sulfo-conjugation. These reactions in the body change bioactivate a procarcinogen. Inhibition of these reactions may help with anti-cancer treatment.
Study shows turmeric and curcumin modulate conjugation
The researchers of the study chose to use a known pro-carcinogen, 1-Napthol, as a model. They used cultured Human colonic adenocarcinoma cells, known as Caco-2 cells. These cells are used as tools for studying intestinal cell function.
The work concludes that both curcumin and turmeric strongly inhibit sulfoconjugation. Since curcumin alone achieved the same levels of inhibition, they conclude that the curcumin activity may largely be responsible for this effect.
dmso dimethylsulfoxide health benefits …The levels of glucuronidation of 1-Napthol were different for turmeric and curcumin, however. The turmeric effect was actually larger than the curcumin effect, possibly suggesting that turmeric contains other ingredients besides curcumin that help inhibit glucuronidation. This could be interesting news, as it implies that the natural spice could do as well if not better in helping the body’s natural detoxification system than the purified curcumin.
The research studied to the level of gene expression the effects of curcumin and turmeric. Other studies have also claimed that turmeric and curcumin can affect the way drugs or chemicals are handled by the body by regulating how they affect gene expression.
This means that not only the biochemical activity of curcumin as an anti-oxidant could be the source of the chemoprotective activity of curcumin and turmeric. It could be that curcumin and turmeric actually affect how the body’s natural genetic defenses are rallied.
That’s the good news, now the bad news
There are serious experimental design problems with this research work as reported. The most glaring problem is a lack of reported data for a control on the DMSO (dimethyl sulfoxide) used to dissolve the curcumin and turmeric. DMSO is itself a very bioactive molecule. DMSO in its own time was examined for many potential health effects, both beneficial and negative.
Perhaps the reviewers of the article had access to more data which was not shown in the published article. If so, it should have been mentioned in the text whether a DMSO only sample was examined.
Another problem is the concentration claimed for the curcumin and turmeric in the materials and methods. An attempt to repeat the stock of 10 grams of turmeric in either 100 ml distilled water or DMSO showed that turmeric is largely left as a sludge at this concentration. It is almost impossible to filter the turmeric in water solution at this concentration.
Where does that leave us?
The results of this study are very interesting, and would need to be investigated more thoroughly and with proper controls. The effects on the conjugation system were definitely observed, we just lack proof that it was indeed curcumin and turmeric which caused the effects.
One of the most interesting aspects of this study is that in comparing the naturally occurring turmeric with the purified curcumin, at least one system seems to react stronger to turmeric. Around the world, interest in curcumin was aroused due to the fact that populations which ingest large amounts of turmeric have lower incidences of certain diseases. The scientific community always prefers to narrow down active biochemicals in plants and try to characterize them.
However, nature often packages bioactive molecules with other beneficial molecules which are not easily defined at first in the laboratory. This study should be the basis of a scientific inquiry into the benefits of whole powdered turmeric. As a treatment, it would be far cheaper than the purified curcumin. If the health benefits exist after cooking, then simply adapting ethnic cuisines heavily using turmeric could be a natural chemopreventive recommendation.
Sources: Biol Pharm Bull. 2006 Jul;29(7):1476-9. Turmeric and curcumin modulate the conjugation of 1-naphthol in Caco-2 cells. Naganuma M, Saruwatari A, Okamura S, Tamura H.