What is NPA and What Does It Mean for Manuka Honey?

When it comes to understanding the nuances of Manuka honey, one term you will likely come across is NPA, or Non-Peroxide Activity. In this article, we’ll dive into the details of NPA, its importance in Manuka honey, and how it relates to the honey’s potency and quality.

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The Origins of Non-Peroxide Activity

Non-Peroxide Activity was first discovered in 1981 by Dr. Peter Molan, who was studying the peroxide activity of honeys worldwide. Molan found that while all kinds of honey have some antibacterial activity due to hydrogen peroxide, Manuka honey possesses a unique and unusual type distinct from other honey types. This particular activity is what we now call Non-Peroxide Activity (NPA).

Peroxide vs Non-Peroxide Activity

To better understand NPA, let’s first explore its counterpart. Peroxide activity (PA) stems from the conversion of glucose oxidase to hydrogen peroxide, a naturally occurring antibacterial property in honey. Low pH levels, high osmolarity, and hydrogen peroxide production contribute to this peroxide activity.

Dr. Molan became intrigued by what would occur when hydrogen peroxide activity (HPA) was intentionally destroyed in honey. His research revealed that most types of honey experienced reduced antibacterial activity in the absence of HPA. However, Manuka honey consistently retained robust antibacterial properties, which are now identified as the unique Non-Peroxide Activity.

NPA and the Methylglyoxal (MGO) Connection

NPA in Manuka honey is largely attributed to the compound Methylglyoxal (MGO), which originates in the nectar of the Manuka plant. As a result, Manuka honey develops non-peroxide antimicrobial activity due to the presence of MGO.

Dr. Molan went on to create the “Molan Gold Standard,” a grading system to define the quality of Manuka honey based on its MGO content, with higher levels being better. However, further studies revealed MGO alone does not account for Manuka honey’s non-peroxide activity, an assertion confirmed by Professor Peter Molan himself.


Understanding the NPA Rating

It is crucial to note that the NPA rating is not a direct measure of antibacterial activity. Instead, it serves as a comparison to a standard reference antiseptic (phenol) with an equivalent level of antibacterial activity.

NPA rating is expressed in percentage, where the index number indicates the % of phenol content in water that’s equivalent to the honey’s antibacterial effects. For example, an NPA 10+ rating suggests the honey’s antibacterial prowess is on par with a 10% phenol solution. The correlation between NPA and Methylglyoxal (MG) levels provides an approximation of the honey’s potency but not a fixed relation.

Factors Influencing NPA Rating

It’s important to note that various factors can impact a honey’s NPA rating, including:

  1. Harvesting: The NPA rating is influenced by the nectar source. Solely harvesting from the Manuka bloom results in a higher rating, while mixing with nectar from other species dilutes it.
  2. Time: Manuka honey’s DHA content transforms into MGO with time, improving its NPA rating and antibacterial properties.
  3. Storage and processing: The conditions under which the honey is stored and processed can alter its quality and NPA rating.

Keep in mind that some producers may artificially add peroxide activity and NPA to achieve higher ratings and increase honey prices. To confirm the claimed quality of a particular product, ask for a certificate from laboratory testing.

Conclusion & Considerations for Consumers

Understanding Non-Peroxide Activity (NPA) is key to appreciating the potency and quality of Manuka honey, but it is not the only benchmark. Remember, the UMF® grading system is another critical indicator to consider.

UMF® (Unique Manuka Factor) is independently certified and internationally recognised as a quality assurance system for New Zealand Manuka honey. Originally based on the NPA test results, it ensures the honey’s authenticity, quality, and safety.


As consumers, it isn’t enough to look at just the NPA values or Methylglyoxal (MG) levels. Always take note of the UMF rating on Manuka honey and use it with the NPA and MG levels to gain a holistic view of the potency and effectiveness of the honey. Also, remember that multiple factors, like the source of nectar, storage conditions, processing methods, and time, can affect the honey’s performance and potency.

Taking the time to read Manuka honey product labels thoroughly and, where possible, requesting a laboratory certificate to confirm a product’s quality is worthwhile. Understanding these elements equips you to make informed decisions, ensuring you buy and enjoy genuinely high-quality Manuka honey, thus reaping its unique benefits to the fullest.

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