What are the health benefits of manuka honey, and is it safe?

Answer:

Manuka honey has unique chemical characteristics and is promoted for use topically for wounds, orally for constipation, and as a mouthwash for gum disease. However, the clinical evidence supporting these uses is weak and, in some cases, based on evidence with honey other than manuka, as described below.

What Is It?
Manuka honey is produced from the nectar of flowers of the manuka bush (Leptospermum scoparium), which is native to New Zealand. It differs from other types of honey due to its high concentration of methylglyoxal (MGO), an antibacterial compound.

New Zealand's manuka honey industry has developed a grading system for manuka honey called the Unique Manuka Factor (UMF). The UMF is a function of the levels of methylglyoxal and other marker compounds for manuka honey. Manufacturers of manuka honey typically advise consumers to choose brands that include a Unique Manuka Factor (UMF) of 15 or greater to ensure that it contains high levels of the antibacterial compound, methylglyoxal.

What does it do?
Topical use for wounds and burns
Since ancient times, honey has been used in topical treatment of wounds and burns. A review in 2015 of published studies concluded that honey appears to heal partial thickness burns more quickly than conventional treatment as well as leaving burns exposed, as well as heal infected post-operative wounds more quickly than antiseptics and gauze. However, the review noted that three studies using manuka honey did not find sufficient evidence that it was more helpful than standard wound care for healing chronic wounds or leg ulcers (Jull, Cochrane Database Syst Rev 2015).

The FDA permits a patented, sterilized manuka honey-based wound dressing called MediHoney to be sold by prescription and over-the-counter for leg ulcers and other wounds (Simon, Evid Based Complement Alternat Med 2009).

As a mouthwash to reduce gum disease
A 22-day, randomized controlled trial of 124 school children in India found that both a manuka honey mouthwash and one made with raw honey each led to a decrease in plaque and gingivitis (gum inflammation) though neither was as effective as standard treatment with chlorhexidine (Singhal, Journal of Indian Society of Periodontology, 2018). The researchers pointed out that, unlike chlorhexidine, honey does not stain teeth, contains no alcohol, artificial colors or sweeteners, and may be more palatable to (and therefore more regularly used by) children.

Oral use
- For cough
Although promoted as a cough reducer, there are no clinical studies with manuka honey for cough. There is, however, a one-day survey study of the parents of 105 children (age 2 to 18) with upper respiratory infections that compared buckwheat honey (1/2 to 2 teaspoons, depending on age) to equivalent amounts of the cough suppressant dextromethorphan or to no treatment. The honey was statistically superior to no treatment. Although its effects were also better rated than those of dextromethorphan, this difference was not statistically significant (Paul, JAMA Pediatrics, 2007).

- For gastrointestinal disorders
Manuka honey is promoted as a treatment for constipation, although, again, there are no published studies in people. However, evidence from other studies suggest a laxative role. One such study was in rats and showed that enema infusions of methylglyoxal (the antibacterial compound in manuka honey) increased diarrhea and other symptoms of irritable bowel syndrome (IBS) (Zhang, PLoS One, 2014). Another study, which used honey that was not manuka but was conducted in people, found that honey may have a laxative effective, likely caused by a high concentration of fructose -- a simple sugar that draws water into the gut and is known to cause diarrhea, bloating, and other digestive symptoms when consumed in excess. Like other honey, manuka honey is high in fructose and this, coupled with the potential laxative effect of methylglyoxal, may help explain why it is promoted for the relief of constipation (Ladas, The American Journal of Clinical Nutrition, 1995).

Manuka honey is also promoted for the treatment of gastric/stomach ulcers caused by Helicobacter pylori (H. pylori). However, a study of 12 individuals with active H. pylori infections who took one tablespoon of manuka honey four times per day showed that all of the participants continued to have the bacteria at the end of two weeks (McGovern, J R Soc Med 1999).

How much does it cost?
Manuka honey costs about $2 to $11 per ounce depending on brand, UMF factor, and other features. This is about six to 31 times the cost of common, store-bought honey (which is about 35 cents per ounce).

Is it safe?
Manuka honey is generally safe but may have a laxative effect when consumed in large amounts. Infants younger than 12 months should not consume honey of any kind due to the risk of infant botulism. Topical administration is also inadvisable for infants.

Although honey has been used on wounds, there is a risk that the honey itself could have microbial contamination, so, unless sterile, it may not be safe for this use. The manufacturers of MediHoney, which is sterile, warn consumers not to use their product if they have a known sensitivity to honey not to use it on third-degree burns or to control heavy bleeding.

All types of honey are high in sugar, making excess consumption inadvisable for use by those with diabetes. The high concentration of fructose in honey may also elevate LDL ("bad") cholesterol and triglycerides.

The American Cancer Society advises people undergoing cancer treatment who have low white blood cell counts to "Avoid Raw honey or honeycomb. Select a commercial, grade A, heat-treated honey instead." The British Dietetic Association also suggests avoiding raw honey for people with low white blood cell counts, as such people are more susceptible to infection from microbes that may be in raw honey.

The bottom line: What makes manuka honey special is a high level of the anti-bacterial compound methylglyoxal, although it can cost six to 31 times as much as common, store-bought honey. Manuka honey, like other honey, may have a laxative effect. Topically, when sterile, it may help heal wounds and burns. It may also be used in mouthwash to reduce gum inflammation, but it is no more effective than standard care. It is generally safe to use (except by infants), but its high sugar content must be considered. Raw honey should not be consumed by people undergoing cancer treatment who have low white blood cell counts.