When exploring the unique qualities of Manuka honey, one term that stands out is NPA. In this article, we’ll delve into what NPA is, its significance in Manuka honey, and its role in determining the honey’s potency and quality.
Understanding Non-Peroxide Activity (NPA)
NPA stands for “Non-Peroxide Activity,” a rating specific to Manuka honey that measures its unique antibacterial potency. Unlike most honeys, which derive their antibacterial properties from hydrogen peroxide, Manuka honey has an additional, stable antibacterial activity that doesn’t depend on peroxide.
Non-Peroxide Activity was first identified in 1981 by Dr. Peter Molan, who was studying the peroxide activity in various honeys worldwide. Dr. Molan discovered that while all honeys have some antibacterial effects due to hydrogen peroxide, Manuka honey showed an unusual, more resilient antibacterial activity independent of peroxide. This distinct property, termed Non-Peroxide Activity, was linked to the floral origin of the honey rather than other factors like acidity or sugar concentration.
Over time, both scientists and beekeepers adopted the term ‘NPA’ to describe this phenomenon. Although some other types of honey occasionally show non-peroxide activity, NPA remains particularly prominent in Manuka honey and other Leptospermum species.
Peroxide vs. Non-Peroxide Activity
To better understand NPA, it helps to distinguish it from peroxide activity (PA). Peroxide activity results from the conversion of glucose oxidase to hydrogen peroxide, a naturally occurring antibacterial element in honey.
Dr. Molan investigated what would happen if the hydrogen peroxide activity in honey was neutralized. His research showed that, for most honey types, blocking hydrogen peroxide significantly reduced their antibacterial properties. However, Manuka honey retained strong antibacterial effects even when peroxide activity was suppressed, highlighting its unique Non-Peroxide Activity.
The Link Between NPA and Methylglyoxal (MGO)
The primary compound responsible for Manuka honey’s NPA has been identified as methylglyoxal (MGO), which develops from a compound called dihydroxyacetone (DHA) found in the nectar. As the honey matures, DHA converts to MGO, enhancing the honey’s NPA.
However, Dr. Molan’s studies indicate that MGO alone doesn’t fully account for Manuka honey’s non-peroxide activity. It’s the synergy between MGO and other naturally occurring compounds in Manuka honey that creates its potent antibacterial effects. While MGO levels can provide an estimate of NPA, a more accurate measure is found in the Unique Manuka Factor (UMF®) grading system.
Decoding the NPA Rating
It’s essential to understand that the NPA rating does not directly measure antibacterial activity but rather compares it to a reference antiseptic, phenol, to gauge the honey’s potency.
The NPA rating is often expressed in terms such as 10+, indicating that the honey’s antibacterial effects are equivalent to a 10% phenol solution. While there is a correlation between NPA and MGO levels, it’s not a fixed relationship, so it’s best to consider both metrics when assessing Manuka honey quality.
The Importance of NPA for Medical Use
The high NPA in Manuka honey makes it highly valued in medical-grade products, especially for wound care. Unlike peroxide-based antibacterial activity, NPA is stable, not easily broken down by body enzymes (such as catalase in body fluids), and remains effective even after sterilization processes like gamma irradiation. These qualities make it ideal for clinical applications in treating skin and wound infections.
Studies have shown that NPA can remain stable for up to seven years when the honey is stored in the dark at around 4°C. This stability is advantageous for medicinal honey products, as it ensures long-lasting antibacterial activity, extends shelf life, and reduces waste.
Factors That Influence NPA Rating
Several factors can affect the NPA rating of Manuka honey:
- Harvesting: Honey harvested solely from Manuka blossoms typically has a higher NPA rating, while blends with other nectar sources may dilute it.
- Time: DHA in Manuka honey gradually converts to MGO, enhancing the NPA rating over time.
- Storage and Processing: The conditions under which honey is stored and processed can impact its NPA rating and overall quality.
Consumers should also be aware that some producers may artificially boost peroxide activity or NPA to achieve higher ratings. Requesting a certificate from lab testing can help verify a product’s authenticity.
Conclusion: What Consumers Should Consider
Understanding NPA is essential for appreciating the potency and quality of Manuka honey, though it’s not the only factor to consider. The UMF® grading system, originally based on NPA test results, now provides a more comprehensive assessment of honey quality. UMF® certification guarantees the authenticity, quality, and safety of Manuka honey.
For a well-rounded view of Manuka honey’s efficacy, consider the UMF® rating alongside MGO levels. Remember that factors like nectar source, storage conditions, processing methods, and aging all influence the honey’s performance and potency.
Taking the time to read product labels carefully and, where possible, requesting a lab certificate can help ensure you’re purchasing genuine, high-quality Manuka honey. This attention to detail allows you to make informed choices and enjoy the unique benefits of Manuka honey to the fullest.
