Composed almost entirely of sugars and water, it is apparent that many of the extraordinary properties ascribed to honey must rely on the multitude of other components present in mere trace proportions.
Defensin-1 is an antibacterial protein derived from bees that is present in both honey and royal jelly and can assist to heal wounds. But what about the celebrated medicinal qualities of Manuka honey – where do they come from? One of the ingredients critical to honey’s antimicrobial activity is hydrogen peroxide, which is produced via the oxidation of glucose catalyzed by an enzyme produced by bees.
Hydrogen peroxide is used as a bleach, but to gain some perspective, the concentration in honey may be 1,500 times less than that found in household disinfectants. Manuka honey also exhibits non-peroxide antimicrobial activity that is largely attributed to methylglyoxal (MGO), a naturally occurring compound that is produced from dihydroxycetone (DHA) as honey matures.
Both MGO and DHA, along with leptosperin (or methyl syringate β-d-gentiobioside, which is found only in the nectar of Manuka plants!), are signature compounds used to grade the authenticity and quality of Manuka honey by ascribing a ‘unique manuka factor’ or UMF which ranges from 5+ to 24+ (the higher the number, the better the product). A confusing variety of rating systems has arisen through marketplace competition, but as an example, UMF-16 honey contains approximately 0.6 grams of MGO per kilogram of honey.
Honey is also known as a rich source of antioxidants, which help negate premature ageing and the development of some chronic diseases. These consist of plant-produced compounds including flavonoids and polyphenols, along with Vitamin B3 (niacin) and Vitamin C (ascorbic acid), which also has antibacterial properties.
Honey is the only food known to contain pinocembrin, a flavonoid associated with improved brain functioning, and with the potential to treat a variety of diseases. Darker honey may contain more antioxidants than lighter varieties, but just how much are we talking about? One study determined the phenolic antioxidants contained in buckwheat honey to total approximately 0.75 milligrams per gram.
Several other important vitamins are derived from plants. In addition to Vitamin C, which is important for immune function and to prevent scurvy, and Vitamin B3, which converts nutrients into energy and repairs DNA, honey also contains thiamine (or Vitamin B1, vital in the growth and function of cells) and riboflavin (Vitamin B2, also essential for growth), as well as other B vitamins. Honey contains around 2-2.5 milligrams of Vitamin C per 100 grams, compared to the daily human requirement of around 80 milligrams. The other vitamins are present in minute concentrations of 0.02 milligrams per 100 grams or less.
Honey also contains a variety of minerals, including sodium, potassium, iron, magnesium, calcium and zinc. Most of these may also be measured in terms of fractions of a milligram per 100 grams of honey, the exception being potassium, which may be as high as 3.5 grams per 100 grams.
Lastly, traces of a diverse array of volatile organic compounds sequestered from nectar sources are responsible for influencing taste and aroma, and offer a unique fingerprint that may also be used to determine the honey’s floral and geographical origin.
Although a low pH and lack of free water are undoubtedly contributing factors, overall it may be concluded that a large part of honey’s legendary therapeutic, healing and antimicrobial powers are attributable to a diverse range of substances, all present in extremely small concentrations, and none of which, acting completely alone, would amount to much. In other words, it is a multifactorial product; like all great recipes, the end result is far greater than the sum of its ingredients.
Finally, although raw honey may contain small amounts of a large number of beneficial factors, it is important to remember that the same cannot be said for honey that has been heated or commercially processed in other ways. Heating, or pasteurisation, is used to improve clarity and texture, and to reduce crystallisation, but it also destroys many of the naturally occurring enzymes and vitamins. Commercial honey may also be filtered and chemically refined, and this results in the removal of advantageous phytonutrients.