Winnie the Pooh’s favourite snack is attracting a lot of research attention, especially the health benefits of Manuka honey. Manuka honey has unique antibacterial properties that can help treat acne, sore throats, eradicate the bacterium, Helicobacter pylori which causes stomach ulcers and, in the form of a sterilised gel, is used medically to treat skin and wound infections. The British National Formulary includes at least 12 different brands of wound dressings impregnated with medical grade honey, which are available for NHS prescription. The majority specify they are made with Manuka honey.
Blossom honey versus honeydew honey
Honey is a sweet, syrupy liquid that consists of water plus two simple sugars, fructose (typically around 42% by weight) and glucose (35%). The clearer the honey, the higher the proportion of fructose, and the runnier the honey, the higher its water content.
Honey is made by bees that have fed on plant nectars and secretions and (look away now if you’re squeamish) the ‘honey-dew’ excretions of plant-sucking insects.
Honeys also contain antioxidant polyphenols and other beneficial components derived from the plants. The flavour and colour of each batch of honey therefore varies depending on the flowers and trees the bees have visited.
Blossom honey is mainly derived from the nectar of flowers. This is described as monofloral honey if the bees have mainly foraged on one type of plant (eg Manuka honey) and multifloral (or polyfloral) honey if the bees feed on a variety of plants (eg forest or meadow blossom honey).
Where bees have mainly harvested their ingredients from plant-sucking aphids, the product is described as honeydew honey.
Labels usually coyly describe the honey as derived from the sap of trees which, ultimately, is true. Honeydew honey tends to be dark, reddish and, in some cases, looks almost black.
What is Manuka honey?
Manuka honey is a monofloral honey made by bees that feed almost exclusively on the nectar of the New Zealand Manuka or tea tree (Leptospermum scoparium) and the closely related Australian Leptospermum polygalifolium. Hives are placed within dense stands of Manuka bush so bees don’t have to go far in their search for the choicest nectar.
Manuka trees produce unique polyphenols with antiseptic and antibiotic actions that give Manuka honey a medicinal edge over other honeys. These include flavonoids such as pinobanksin, pinocembrin and chrysin and phenolic acids.
Some, but not all, Manuka honeys contain an antibacterial agent called methylglyoxal, which is formed by a caramelizing interaction between the sugars and the other natural ingredients derived from the Manuka tree.
Manuka honey contains methylglyoxal (MGO) in concentrations that are up to 1000 times greater than those found in other honeys and provides the most important non-peroxide, antibacterial activity.
Manuka honey UMF and NPA ratings
The antibacterial activity of Manuka honey is assessed by how well it kills the skin bacterium, Staphylococcus aureus, compared to a known strength of phenol (a strong, carbolic disinfectant).
A Manuka honey whose antibacterial activity is equivalent to a 10% phenol solution is traditionally said to be ‘Active’ as this is the minimum inhibitory concentration to combat bacteria in laboratory tests. This may be labelled on some brands as a Unique Manuka Factor rating of 10, or UMF10.
A Manuka honey with a UMF rating of between 10 and 11.9 is described as UMF10+.
A Manuka honey with a rating between 12 and 14.9 is described as UMF12+ and so on.
To obtain the medicinal benefits of Manuka honey, select a product with a rating of at least UMF 15+. Any genuine Manuka honey with a valid UMF15+ rating will have the same antibacterial activity as another with a UMF15+ rating, regardless of its cost.
Because UMF is a quality trademark in New Zealand, other measures were developed to assess the antibacterial activity of Manuka honey. Non-Peroxide Activity (NPA), for example, measured the antibacterial activity of the Manuka honey against phenol. A Manuka honey rated as NPA10+ is equivalent in antibacterial strength to one labelled UMF10+.
Manuka honey MGO ratings
New Zealand has now adopted a more empirical approach and labels must declare the methylglyoxal (MGO) concentration present in each batch of Manuka honey (measured in mg/kg or parts per million). This may be displayed as a UMF, MG or MGO rating. Terms such as Non-Peroxide Activity (NPA), ‘Active’ and ‘Bioactive’ are no longer permitted, although these terms are still seen on Manuka honeys produced in other countries.
A honey with a methylglyoxal level of 300+ MGO contains a minimum methylglyoxal concentration of 300mg/kg, which is roughly equivalent to the UMF10+ and NPA10+ ratings.
To obtain the medicinal benefits of Manuka honey, select a product with an MGO, rating of at least 250+.
Honeys with higher MGO ratings have greater antibacterial properties but also have a more medicinal taste, which is not to everyone’s liking.
Low-grade Manuka honeys
Manuka honeys without a minimum methylglyoxal (MGO) level on the label are likely to be low-grade honeys.
These may be labelled as ‘Active’ or ‘Bioactive’ and the number shown (eg 24+ Bio Active Manuka Honey) is a measure of the hydrogen peroxide activity present – this occurs in almost all honeys. There may be little MGO activity present, and the honey will usually be significantly cheaper than a high-grade Manuka honey with greater antibacterial action.
If you are just buying honey to spread on toast or dollop into porridge, this grade is fine (and likely to taste delicious). But, if you are seeking the health benefits of Manuka honey, only select a genuine raw Manuka honey, with a declared MGO level of at least 250+.
Honeys that are pasteurised are best avoided as heat inactivates some of the active antibacterial components.
Honey contamination with Campylobacter
Low grade honeys may be contaminated with the spores of Campylobacter – a bacterium that is the source of botulism poisoning.
Laboratory studies show that high-grade Manuka honey can inhibit Campylobacter at dilutions of as much as 1 in 100 (1% strength). This suggests that Manuka honey may still inhibit the growth of Campylobacter after dilution by digestive fluids but this is still under investigation.
NB Honey should not be given to infants under the age of 1 year (not even the smallest amount, and not even Manuka honey) as any botulism spores present may reactivate to produce their toxin in their immature gut. Once an infant reaches the age of 12 months, their digestive and immune system are mature enough to fight off this threat.
Manuka honey and wound infections
All honeys absorb fluid due to their high concentration of natural sugars. This strong osmotic effect makes it difficult for bacteria to thrive. Most honey also contains natural antiseptics such as hydrogen peroxide and gluconic acid. In addition, high-grade Manuka honey contains known amounts of antibacterial methylglyoxal.
Honey has been used as a poultice since ancient times. By absorbing fluid from a wound and suppressing bacterial growth it can both prevent and treat infection as well as promoting healing. The natural growth factors and sugars present also stimulate cell renewal.
Manuka honey is active against a wide range of common skin bacteria, including Staphylococcus aureus (a bacterium that triggers pus formation to form boils and abscesses), and Group A Streptococcus pyogenes (which can cause spreading cellulitis infections). Manuka honey can even inhibit the growth of methicillin-resistant Staphylococcus aureus (MRSA) by preventing bacterial division. Manuka honey can eradicate MRSA from 70% of colonized, chronic venous ulcers and it also has a synergistic effect with antibiotics such as oxacillin that are used to treat MRSA infections.
According to a medical paper published in 2010, no honey-resistant bacteria have been isolated from wounds, and even when bacteria are incubated with sub-lethal doses of Manuka honey, no permanent honey-resistant mutants developed. This makes Manuka honey a highly effective treatment for infected wounds, which is rapidly gaining ground in clinical practice.
Absorbent dressings impregnated with Manuka honey are used under medical supervision to draw fluid out of the infected area and inhibit the growth of skin bacteria. Dressings are usually changed at least three times a day.
Clinical trials show that Manuka honey acts as a biological dressing to deodorize wounds, reduce infection and pain, and promote wound healing with less risk of scarring by:
- Providing a moist healing environment, though which new cells can readily ‘leapfrog’ to grow into an open wound
- inhibiting bacterial growth
- stimulating immune responses
- reducing inflammation
- providing a non-stick surface to minimise disturbance of new cells during dressing changes
- Promoting tissue growth and providing nutrients to ‘feed’ new cells.
In people with diabetic foot ulcers, average healing time with Manuka honey-impregnated dressings was 31 days compared with 43 days with conventional dressings. Infected ulcers became sterile during the first week in 78% of those using the Manuka honey dressings, compared with 35% of those using conventional dressings.
Manuka honey has also been used to treat acne, cracked nipples, burns, eczema, cuts and grazes, impetigo, radiation-induced inflammation, and to treat fungal skin infections.
Medihoney Wound Gel is a medical grade topical treatment that is used to treat skin conditions such as acne, wounds and burns.
NB Do not apply raw, edible Manuka (or other honeys) to wounds. Only use sterilised medicinal honey gels that are available from pharmacies, such as Medihoney.
Manuka honey and sore throats
Most of us have used honey to sooth a sore throat. Its thick consistency coats the throat to ease pain, its antibacterial properties start working against any causative bacteria, while its immune boosting properties help to fight cold viruses. And as a bonus, it tastes good! You can slowly dissolve a tablespoon of Manuka honey in your mouth, or add it to warm water with the juice of half a lemon to make a soothing drink.
Although no clinical trials have assessed the effectiveness of Manuka honey in treating sore throats, researchers have found that Manuka honey stimulates immune cells and that it can prevent the growth of Streptococcal bacteria that can cause sore throats and tonsillitis.
In fact, as I write this, I’m slowly dissolving a tablespoon of Manuka honey in my mouth to see off a sore throat that’s doing the rounds.
Manuka honey is also used to soothe mouth and throat inflammation following radiotherapy and chemotherapy.
Steens Raw Manuka Honey is an unpasteurised, cold-pressed 100% pure New Zealand Honey. It is a best seller for treating sore throats, cough and to aid digestion.
Manuka honey and Helicobacter pylori
Helicobacter pylori is a motile bacterium that burrows into the mucous lining of the stomach, leaving a breach that exposes the stomach wall to acid attack. H. pylori also produces ammonia gas to surround itself in a cocoon-like bubble that protects it from stomach acid. This ammonia irritates the stomach wall, and increases secretion of hydrochloric acid.
Although Helicobacter infections doesn’t cause symptoms in everyone, virtually all patients with duodenal ulcers are infected, plus 90% of those with gastric ulcers. In laboratory studies, Manuka honey is the only honey able to kill Helicobacter even when diluted twenty-fold to form a 5% solution.
When used to help eradicate Helicobacter pylori, Manuka honey is usually taken on an empty stomach at a dose of four teaspoons, four times per day, for eight weeks. NB check with your doctor before trying this remedy if you are on medication, or have diabetes. This treatment provides around 80 kcals per dose.
If a wound fails to heal rapidly, or becomes infected, seek medical advice.
Always seek medical advice about persistent or recurrent indigestion.
If you have diabetes, consult your doctor before trying any honey treatments.