Honey is a carbohydrate food that contains mainly glucose and fructose at around 80g per 100g. The ratios of glucose and fructose can vary based on the botanical origins of the honey, and as a result the glycaemic index can vary considerably with the monosaccharide composition (from 35 to 74). Compared to sucrose, honey ingestion may produce a reduction in glycaemic response and an increase in satiety, and this may explain honey’s anti-obesity effects. In addition to carbohydrate, honey also contains a number of other compounds such as micronutrients, polyphenols, acids, proteins and free form amino acids. This nutritional profile is believed to give honey unique properties and specific health benefits against a number of diseases and conditions. The exact benefits of honey appear to depend on the origin of the honey as differing compositions can affect the health benefits to the consumer.
Honey contains glucose oxidase, an enzyme that catalyses the conversion of glucose to hydrogen peroxide, and this gives honey a general antimicrobial activity. However, some types of honey can contain catalase, an enzyme that can catalyse hydrogen peroxide to water, thus decreasing its activity. Honey is particularly effective against gram positive bacteria, but can inhibit the growth of other microorganisms including fungi and viruses. Some of the microorganisms that are affected by honey include Escherichia coli, Helicobacter pylori, Salmonella sp., Shingella sp., Staphylococcus aureus, Streptococcus sp. and Vibrio cholerae. Various aromatic acids and flavonoids may also possess antimicrobial activity, based on results from in vitro studies. The antimicrobial effects of honey may provide protection against dental caries, dental plaque, peptic ulcers caused by Helicobacter pylori and other gastric lesions. The low pH of honey can also contribute to its antimicrobial activity.
Honey possess antioxidant effects that are beneficial at lowering systemic oxidative stress, and may therefore protect against certain diseases such as cancer, cardiovascular disease and diabetes. Honey likely possesses antioxidant activity because of the polyphenol and vitamin C content. The total polyphenol concentration is correlated with the oxygen radical absorbance capacity (ORAC) suggesting that the polyphenols are the main contributor to the antioxidant activity of honey. Subjects fed 1.5g/kg of buckwheat honey had an increase in the antioxidant capacity of serum and the reducing capacity of serum. In another study, supplementation of subjects with honey caused an increase in a number of plasma antioxidants including vitamin C (47%), β-carotene (3%), uric acid (12%) and glutathione reductase (7%). The antioxidant capacity of honey depends on the geographical origin of the honey, as the surrounding flora influences the polyphenol content substantially.
Other effects of honey include anticancer effects, antiinflammatory effects and immune modulatory effects. Honey may be able to protect against cancer because it has in vitro antitumor and antimutagenic effects. For example various type of honey have been shown to protect against cellular damage from heterocyclic amines using an Ames assay, and the antimetastatic effects of honey in cell culture models has also been demonstrated. Ingestion of 70g of honey caused a reduction in inflammatory eicosanoids in humans and reductions in the inflammatory diseases of the gut, including colitis and inflammatory bowel disease, in animal models. These gut antiinflammatory effects may relate to the antimicrobial activity of honey, described earlier. Some evidence also suggests that honey can modulate immunity, with suppressive effects being effective against pollen hypersensitivity and stimulatory effects increasing plasma concentrations of white blood cells.
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