Manuka honey is known and prized for its supposed ‘health benefits’. Are there any?
But with more sold than produced – some dodgy dealing going on?
What is Manuka Honey?
Manuka honey originated in New Zealand. It is made from nectar collected by bees that forage on the wild manuka tree.
Most honey has some bacteria killing properties because of: its high sugar content; it contains chemicals that produce hydrogen peroxide; Munka honey conatins all this plus methylglyoxal (MGO), which has antimicrobial properties.
Why is it reputed to have health benifits?
A 1991 study from the Honey Research Unit in New Zealand, showed that when hydrogen peroxide is removed from honey; manuka honey alone is the only type that retained its ability to kill bacteria. This is because of the presence of MGO.
Medical grade honey is licensed around the world for wound care. Research from Cardiff University shows that honeys in general, and particularly manuka honey, are effective with chronic wounds and MRSA (antibiotic-resistant infection).
However, honey used in this capacity is medical-grade with the impurities removed.
People buy Manuka honey thinking that helps with sore throats, gut problems or even allergies. There no evidence that MGO survives being eaten or that it does any good at all inside the body.
There is a small bit of evidence that honey can soothe a sore throat, but none to suggest that eating shop-bought manuka honey is any more effective than a cheaper honey. There isn’t any scientific evidence to show it can ease indigestion.
The labelling on Manuka honey jars is confusing.
Manuka honey is marketed with a UMF number – “Unique Manuka Factor” – this indicates how many bacteria the honey could kill, once the hydrogen peroxide has been removed because of the MGO. Some jars show MGO.
Other labels show NPA or TA. NPA (non-peroxide activity) is based on the amount of MGO the honey contains and TA (total activity) includes the both the MGO and hydrogen peroxide activity. Some jars have ‘Activity’ / ‘Active’ next to numbers; and some have numbers alone with no explanation.
This is a confusing and poorly regulated area; the U.K. Food Standards Agency are meant to be investigating.
For the non biochemists – hydrogen peroxide
Hydrogen peroxide H2O2) kills bacteria by oxidizing their cell walls; this means ‘stealing’ an electron. This damages the bacteria.
Hydrogen peroxide is made up of two hydrogen atoms and two oxygen atoms. It is similar to water ((H2O) two hydrogen atoms and one oxygen atom)) but it has an extra oxygen atom, which makes it very reactive and unstable.It is known as a ‘free radical’ (there are many other free radicals produced by the body).
The extra, destructive, oxygen, has an unpaired electron and because molecules are only stable when electrons are paired, it reacts with other bio molecules (as well as bacteria) stealing their electrons (and damaging them).
In the body an enzyme (catalase) breaks hydrogen peroxide down before it does much damage. Nearly all free radicals are formed naturally in the body during aerobic respiration (the process of using oxygen to make energy); few arise from environmental pollution. The focus on dietary antioxidants (mostly vitamins) is because free radicals can damage human cells and DNA.
However, most of the research has shown that anti oxidant supplements have done more harm than good (see post on supplements).
Hope it’s not too complicated.