Prepared by Dr Carolyn Lister, New Zealand Institute for Plant & Food Research Ltd
The Health Benefits of Antioxidants
The word “antioxidant” is increasingly appearing in the popular press. Food and supplement industries are increasingly using marketing claims that relate to the antioxidant status of specific Foods, e.g. “best source of antioxidants”, “world’s strongest antioxidant”, “superior antioxidant levels compared with red wine”. However, the science behind antioxidant efficacy is complex and may lead to confusion.
Human studies have shown that consumption of plant-based foods (e.g. fruits, vegetables, honey etc) may reduce the risk of various diseases including cancer, cardiovascular disease, cataracts, and other age-related disorders. Among various modes of action it is thought that oxidative stress can cause damage to cells and this may contribute to these diseases. Oxidative stress occurs when free radicals and reactive oxygen species are out of balance with our body’s ability to deal with them. Antioxidants are compounds that act as free radical scavengers, i.e. they can neutralise the damaging free radicals. Because of the huge interest in the role of diet in preventing disease, many thousands of scientific publications on antioxidants have appeared in the last couple of decades. Some studies have examined the antioxidants in honey.
The Composition of Honey
Honey is a natural product produced by bees from the nectar of various flowers or collected from the sticky liquid secreted by aphids and some scale insects as they feed on plant sap. These different botanical origins give rise to nectar honey or honeydew honeys respectively. Honey contains a great variety of different compounds. In particular, it contains different antioxidant substances, such as phenolics, ascorbic acid and other organic acids, hydrogen peroxide, hydroxymethylfurfural, and amino acids. These compounds are found to a different extent in honey, depending mostly on the botanical origin of honey. Phenolics are the main class of compounds in honey and honeydew that have in vitro antioxidant activity. It has been reported that total phenolic content may be more useful than the radical-scavenging assay for reporting antioxidant capacity in honey. Darker honeys usually have more phenolic compounds compared with light-coloured honeys. Studies have shown that honeydews show higher phenolic content and antioxidant activity than nectar honeys.
Measuring Antioxidant Activity/Phenolic Content
The focus on antioxidants has led to a demand for information from diverse end-user groups. In order to make meaningful comparisons between foods and to set standards for regulatory and health claims it is important that data collection is standardised. Numerous in vitro methods are used to evaluate the antioxidant potential of natural products. Studies have shown strong correlations between antioxidant activity and honey colour or Total Phenolic content. It has been concluded that the measurement of Total Phenolics provides the best overall scientific and accurate chemical marker for measuring antioxidants in honey. This method can be compared to the use of methylglyoxal as the chemical marker for Manuka Honey.
The rating system for the Total Phenolic content of honey is as follows:
- BeeBio Standard 5+ = Total Phenolics 50 mg/100 g = 500 mg/kg
- BeeBio Standard 10+ = Total Phenolics 60 mg/100 g = 600 mg/kg
- BeeBio Standard 15+ = total Phenolics 70 mg/100 g = 700 mg/kg
The rating system for the Methylglyoxal content of Manuka Honey is as follows
- BeeBio Standard 5+ = Methylglyoxal 10 /100 g = 100 mg/kg
- BeeBio Standard 10+ = Methylglyoxal 30 /100g = 300 mg/kg
- BeeBio Standard 15+ = Methylglyoxal 55 /100g =550 mg/kg