Sugar (primarily sucrose) has been a part of the daily diet for literally hundreds of years, but research is now suggesting that sugar intake can be detrimental to our health. In particular, excessive consumption of simple sugars with high glycemic index (GI) values have been shown to cause overeating and weight gain. As well, elevated postprandial hyperglycemia can result after consuming sugars and this has been linked to disease formation and progression, the development of advanced glycation endproducts, inflammation and increased mortality rates. Honey has been recognised as having a number of beneficial health properties, including slower uptake into the bloodstream, a pharmacological action of reducing blood glucose levels and a high level of bioavailable antioxidants, all of which may mean that honey could be less harmful to health than sucrose in the diet. This study was therefore designed to investigate the health benefits of honey in the diet as a replacement for sucrose, using small animal studies. As well, because of the interest in using honey as a replacement for sucrose in sweetened dairy foods, a small number of in vitro investigations were carried out to determine whether honey could retain its bioactive properties when combined with milk/dairy products. Using the in vitro studies, it was shown that the combination of milk with honey had no effect on either the antibacterial or antioxidant capabilities of honey. During the animal feeding studies a number of significant findings were observed. In the earlier work it was shown that honey had a significant effect on protein metabolism when fed for 14 days at a level of 600 g/kg diet (comprising 480 g sugars and 120 g water) compared with animals fed an equivalent amount of sucrose. In this study, honey-fed rats exhibited significantly lower weight gains (p less than 0.001), food intake (p less than 0.05) and nitrogen intakes (p less than 0.05) and significantly higher faecal nitrogen outputs (p less than 0.05) compared with sucrose-fed rats. Animals fed a diet consisting of 480 g/kg of mixed sugars as in honey generally exhibited protein metabolism parameters that were comparable to those of the sucrose-fed rats, suggesting that the effects of honey on protein metabolism were not due solely to its distinctive sugar composition. Furthermore, in another study that specifically investigated the effects of honey on weight regulation, honey (100 g/kg diet) resulted in significantly reduced weight gain after 6 weeks (p less than 0.01) compared with animals fed the same amount of sugars as sucrose, although food intake was not reduced in this study. Percentage weight gains were shown to be comparable between honey-fed rats and those fed a sugar-free diet, suggesting that differences in glycemic control may be partly responsible for the results seen. Fasting lipid profiles and blood glucose levels were also measured in this study, but no significant differences were observed between diet groups. During long-term (12 months) feeding weight gain was again significantly reduced in rats fed honey (p less than 0.05) and a sugar-free diet (p less than 0.01) compared with those fed sucrose, the weights of honey-fed rats and those fed the sugar-free diet being comparable at the end of the study. In addition, blood glucose levels were significantly lower (p less than 0.001), and HDL-cholesterol levels significantly higher (p less than 0.05) in animals fed honey compared with those fed sucrose after 52 weeks, but no differences in these parameters were observed between rats fed sucrose and a sugar-free diet. No other significant differences in lipid profiles were observed. Immunity measures were improved after feeding honey or sucrose for 52 weeks, animals in both of these diet groups having significantly higher levels of neutrophil phagocytosis compared with those fed the sugar-free diet (both p less than 0.0001). In addition, the percentage of leukocytes that were lymphocytes was significantly higher in honey-fed rats at the end of the study. Furthermore, levels of oxidative damage in aortic collagen were significantly reduced in rats fed honey or the sugar-free diet (both p less than 0.05) compared with those fed sucrose after 52 weeks. Full body DEXA scans were also undertaken in this 12-month study to assess body fat levels and bone mineral composition and density, although they revealed few statistically significant differences. Percentage body fat levels were shown to be nearly 10% lower in honey-fed rats compared with sucrose-fed animals at the end of the study (p less than 0.05), but no other significant differences between diet groups were observed. With one exception, no differences in bone mineral composition or bone mineral density were observed between the three diet groups after 52 weeks. This data agreed with the results generated from two earlier studies that showed that feeding honey short-term (for 6-8 weeks) to rats that were either calcium-deficient or fed a low calcium diet had no effect on bone calcium levels, bone mineral content, bone mineral density or bone breaking parameters. Lastly, long-term feeding of honey to rats had a number of statistically significant effects on anxiety and cognitive performance when assessed using animal maze tasks. Anxiety-like behaviour was significantly reduced in honey-fed rats overall compared with those fed sucrose (p = 0.056) or a sugar free diet (p less than 0.05). Spatial memory was also better in honey fed-rats throughout the 12 month study, these animals not displaying the same degree of age-related spatial memory loss seen in the other two diet groups. No significant differences in recognition memory or learning capability were observed between diet groups after 52 weeks. In conclusion, both short-term and long-term feeding of honey result in a number of health benefits compared with eating similar amounts of sucrose. These include less weight gain, improved immunity, reduced levels of oxidative damage and improved cognitive performance.. These effects of honey are likely to occur through a number of different processes, although the presence of high concentrations of antioxidants and other minor components in honey are likely to be important contributors. Honey may therefore help to improve human heath if it is used as an alternative to sucrose in foods and beverages, although feeding studies in humans are required to assess its efficacy. In addition, more animal studies are needed to assess which features of honey (e.g. fructose content, antioxidant content and bioactivities) are required to achieve optimal effects, and to determine what impact heating and food processing may have on the beneficial health effects of honey.
| Identifer | oai:union.ndltd.org:ADTP/238033 |
| Date | January 2008 |
| Creators | Chepulis, Lynne Merran |
| Publisher | The University of Waikato |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | http://www.waikato.ac.nz/library/research_commons/rc_about.shtml#copyright |
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