What is NF-κB (nuclear factor kappa B)?
NF-κB (nuclear factor kappa B, also NF-kB) is a transcription factor: a protein complex that switches certain genes on and off in cells, above all those for inflammation and immune response. It is therefore often called the “master switch” of inflammation.
NF-κB explained simply
In resting cells NF-κB is bound to inhibitor proteins in the cytoplasm and inactive. On a stimulus – pathogens, cell stress or messengers such as TNF-α – this brake is released, NF-κB moves into the cell nucleus and switches genes on. These include inflammatory messengers such as interleukin-6 and enzymes such as COX-2.
That is basically useful, as it is how the body responds to infection and injury. A permanently overactive signalling chain is the problem, and it is linked to chronic inflammatory processes, for example silent inflammation.
The fire-alarm picture
A helpful image: NF-κB is like the main switch of a fire alarm. In real danger it has to trigger. If it triggers constantly for no reason, you get permanent alarm. This picture is a simplification, because NF-κB is a network of several proteins with many tasks, including outside inflammation.
NF-κB and curcumin
In cell and animal experiments curcumin inhibits the NF-κB pathway. It is one of the most frequently cited mechanisms when explaining how curcumin might act in the body. Similar effects are discussed for some pungent compounds of other spices.
Important context:
- Many of these findings come from laboratory experiments with partly very high concentrations that are not reached in human blood.
- An inhibited pathway in a cell is no proof of a particular effect in people. Clinical studies are what count.
- How long curcumin would need to be taken to show an effect is unclear.
For curcumin to reach any target at all, it must be absorbed. Ordinary curcumin reaches the blood only to a very small extent. More under bioavailability.
How is NF-κB built and activated?
NF-κB is not a single protein but a family of five related proteins that pair up. The best-known combination is p50/p65. At rest an inhibitor protein called IκB keeps them in the cytoplasm. Signals such as cytokines, bacterial components or oxidative stress activate an enzyme (IKK) that tags IκB for degradation. The way into the nucleus is then open.
This cascade is fast and can reinforce itself, because NF-κB switches on genes for messengers that in turn activate NF-κB. That is why the pathway is studied so intensively in chronic inflammation research – and why the simplification of “one switch” should be treated with caution.
Frequently asked questions
How is NF-κB written? The “κ” is the Greek letter kappa. In plain texts you also find NF-kB or NF-kappa-B; the same factor is meant.
Is it good to inhibit NF-κB? Not across the board. The pathway matters for fighting infections. Targeted influence on overactive processes is a research topic; a general “switch-off” would not be desirable.
What does this have to do with daily life and diet? Various plant compounds are linked to NF-κB in lab studies. Health statements for humans, however, require clinical studies.
