Mānuka honey is a monofloral honey produced in Australia and New Zealand from the nectar of the mānuka tree. The honey is commonly sold as an alternative medicine. While a component found in Manuka honey has demonstrated antibacterial properties in vitro, there is no conclusive evidence of benefit in medical use and no evidence that the whole honey has any benefit beyond its nutritional content.
Mānuka honey is produced by introduced European honey bees (Apis mellifera) feeding on the mānuka or tea tree (Leptospermum scoparium) which grows uncultivated throughout New Zealand and southeastern Australia.
Mānuka honey is markedly thixotropic and has shown the highest viscosity among a range of studied honeys. This property is due to the presence of a protein or colloid and is its main visually defining character, along with its typical dark cream to dark brown colour. To be labelled New Zealand mānuka honey, at least 70% of its pollen content should come from Leptospermum scoparium.
The mānuka tree flowers more or less at the same time as Kunzea ericoides, another Myrtaceae species also called Kānuka, which often shares the same growing areas as the former species. Some apiarists cannot readily differentiate these two species from each other. Both flowers have a similar morphology and pollen differentiation between the two species is very difficult. Therefore, melissopalynology as identification for the type of honey is valid only in association with other identification tests. In particular, L. scoparium honey is dark, whereas K. ericoides honey is pale yellow and clear, with a "delicate, sweet, slightly aromatic" aroma and a "sweet, slightly aromatic" flavour, and is not thixotropic.
Heather (Calluna vulgaris) honey is also thixotropic, but the plant flowers in late summer and its montane distribution in north temperate Europe and central Asia does not correspond with that of Leptospermum scoparium. Therefore, its harvest cannot be mistaken for that of manuka honey.[clarification needed]
Manuka honey has a strong flavour, which has been characterised as, "earthy, oily, herbaceous", and "florid, rich and complex". It is described by the New Zealand honey industry as having a "damp earth, heather, aromatic" aroma and a "mineral, slightly bitter" flavour.
A 2008 Cochrane Review found that there was insufficient evidence from existing studies to conclude that honey helps improve superficial burns compared to some types of standard dressing. However, very few studies within the review included Mānuka honey. The review concluded that the use of any honey, including Manuka honey, for leg ulcers provides no benefit, and that there was insufficient evidence for any benefit in other types of chronic wounds. The studies of higher quality demonstrated honey had no significant effect or had a worsened effect on healing time. Mānuka honey does not reduce the risk of infection following treatment for ingrown toenails.
The correlation between UMF and MGO in Manuka honey is as follows:
UMF5+ = MGO 83+ mg/kg UMF10+ = MGO 263+ mg/kg UMF15+ = MGO 514+ mg/kg UMF20+ = MGO 829+ mg/kg UMF25+ = MGO 1200+ mg/kg
Official UMF website 
In the wake of the high premium paid for mānuka honey, the majority of product now labelled as such worldwide is counterfeit or adulterated. According to research by UMFHA, the main trade association of New Zealand mānuka honey producers, whereas 1,700 tons of mānuka honey are made there annually representing almost all the world's production, some 10,000 tons of produce is being sold internationally as mānuka honey, including 1,800 tons in the UK.
In governmental agency tests in the UK between 2011 and 2013, a majority of mānuka-labelled honeys sampled lacked the non-peroxide anti-microbial activity exclusive to mānuka honey. Likewise, of 73 samples tested by UMFHA in Britain, China and Singapore in 2012-13, 43 tested negative on the same count. Separate UMFHA tests in Hong Kong found that 14 out of 55 mānuka honeys sampled had been adulterated with syrup. In 2013 the UK Food Standards Agency asked all trading standards authorities to alert all mānuka honey vendors to the need for legal compliance.
There is a confusing range of systems for rating the strength of mānuka honeys. In one UK chain in 2013, two products were labelled “12+ active” and “30+ total activity” respectively for “naturally occurring peroxide activity” and another “active 12+” in strength for “total phenol activity”, yet none of the three was labelled for the strength of the non-peroxide antimicrobial activity specific to mānuka honey.
One reason for bona fide mānuka honeys to vary in the last regard is that the bees cannot be forced to forage only on mānuka flowers, especially given the pressures toward maximal exploitation of known blooms. So intense is the demand for the correct trees that New Zealand honey farmers have been using helicopters to locate them and deploy hives nearby. There have been increasing turf disputes between producers operating close to large mānuka tree clumps, and also cases reported of many hives being variously sabotaged or stolen.
At least one British supermarket has taken to stocking jars of the honey in tagged security cassettes, such were the losses from shoplifting.
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It (Leptospermum scoparium) is native to New Zealand and Australia"
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