Denise C. Hunter

Stability of antioxidants in an apple polyphenol-milk model system

The stability of antioxidants in an apple polyphenol-milk model system was examined. The model system consisted of skim milk fortified with pH-neutralised apple polyphenols (AP, 0-200mg per 100ml milk), with or without ascorbic acid (100mg per 100ml milk). Physical and chemical changes were evaluated after thermal treatment (120°C, 5min) and oxidative storage (20°C and 38°C, up to 12 weeks). Antioxidant capacity was determined using both oxygen radical absorbance capacity (ORAC) assay and ferric reducing antioxidant power (FRAP) assay. Significant antioxidant capacity was detected in the presence of milk. Antioxidant capacity was retained during thermal treatment but decreased slowly during storage. The concentration of ascorbic acid decreased rapidly, and was close to zero after 2-week storage at 38°C or 10-week storage at 20°C. The brownness of the polyphenol-milk system increased over storage duration of 0-12 weeks; this effect was retarded by the addition of ascorbic acid. This high polyphenol-milk has demonstrated good physical stability.

Changes in markers of inflammation, antioxidant capacity and oxidative stress in smokers following consumption of milk, and milk supplemented with fruit and vegetable extracts and vitamin C.

Two milk-based beverages delivering twice the average daily antioxidant intake were formulated, based on synergistic combinations of fruit and vegetable extracts, and containing vitamin C (1.00 mg/ml) for shelf stability. Smokers (n = 42) consumed prototype milk A, B or non-supplemented milk (no extracts or vitamin C; 200 ml) twice daily for 6 weeks. Fasting and post-prandial (2 h after milk consumption) blood samples were collected at baseline and the end of each treatment. Non-supplemented milk significantly reduced fasting inflammatory cytokines (interleukin (IL) 6, IL-1β, tumour necrosis factor-α) compared to baseline. Both supplemented milk-based beverages significantly increased fasting plasma vitamin C concentrations and antioxidant potential and decreased serum uric acid, compared to non-supplemented milk. The beverages did not induce post-prandial oxidative stress or inflammation. Therefore, regular consumption of the supplemented milks may confer health benefits because of increased antioxidant potential or through mechanisms resulting from increased vitamin C or decreased uric acid concentrations.

No difference in fecal levels of bacteria or short chain fatty acids in humans, when consuming fruit juice beverages containing fruit fiber, fruit polyphenols, and their combination ☆

This study examined the effect of a Boysenberry beverage (750 mg polyphenols), an apple fiber beverage (7.5 g dietary fiber), and a Boysenberry plus apple fiber beverage (750 mg polyphenols plus 7.5 g dietary fiber) on gut health. Twenty-five individuals completed the study. The study was a placebo-controlled crossover study, where every individual consumed 1 of the 4 treatments in turn. Each treatment phase was 4-week long and was followed by a 2-week washout period. The trial beverages were 350 g taken in 2 doses every day (ie, 175 mL taken twice daily). The hypothesis for the study was that the combination of polyphenols and fiber would have a greater benefit on gut health than the placebo product or the fiber or polyphenols on their own. There were no differences in fecal levels of total bacteria, Bacteroides-Prevotella-Porphyromonas group, Bifidobacteriumspecies, Clostridium perfringens, or Lactobacillus species among any of the treatment groups. Fecal short chain fatty acid concentrations did not vary among treatment groups, although prostaglandin E2 concentrations were higher after consumption of the Boysenberry juice beverage. No significant differences were found in quantitative measures of gut health between the Boysenberry juice beverage, the apple fiber beverage, the Boysenberry juice plus apple fiber beverage, and the placebo beverage.

Kiwifruit and Health

Publisher Summary The word “kiwifruit” is widely used for plants in the genus Actinidia Lindl., and the fruit they produce. Kiwifruit are often promoted for their high vitamin C content, which probably contributes to the health benefits observed. Dieticians along with other health professionals have the responsibility of providing consumers with scientifically supported knowledge to help them make informed dietary decisions. The scientific information supporting the unique health benefits of kiwifruit is growing rapidly. There is evidence from in vitro cell studies and animal models. Such evidence must be validated by human intervention trials. Oxidative stress may play a role in the pathogenesis of cardiovascular disease, the leading cause of death in developed countries. The strongest evidence for a health benefit of kiwifruit is in the area of intestinal well-being. Intestinal well-being is an ill-defined state often equated with an absence of symptoms. Bowel habit is a useful overall biomarker of gut function, particularly colonic function. Kiwifruit have been shown in two intervention trials to contribute to gastrointestinal well-being by their positive effects on laxation in targeted groups of subjects, the elderly, and those suffering from constipation. A diet rich in fruits and vegetables offers health and wellness benefits that go beyond basic nutrition. Consumption of green kiwifruit contributes by having positive effects on cardiovascular and gut health.

Chapter 12 – Kiwifruit and health

Abstract There is increased interest in the health benefits of food, and more and more evidence that a diet rich in fruit and vegetables promotes health and wellness by protecting the body against degenerative diseases. Kiwifruit are widely known to contain high concentrations of vitamin C, and this has been linked in the past to their health benefits. However, kiwifruit also contain other vitamins, minerals, phytochemicals such as carotenoids, polyphenolics, and fiber that may provide health benefits beyond basic nutrition. Here we review the evidence for the health benefits of kiwifruit. The benefits mainly fall into the health target areas of protection from oxidative stress and mutagenesis, cardiovascular health, gut health, and immune function. There are numerous studies using cell-based models and supporting data from animal feeding trials demonstrating positive effects related to particular kiwifruit cultivars. A limited number of human intervention trials validate some of these health benefits for kiwifruit in the areas of “natural protection” (protection from oxidative stress and DNA damage associated with mutation and cancer), gut health (laxation and healthy bowel habits), recovery from symptoms of cold and flu, and cardiovascular health (reduction in platelet aggregation). Kiwifruit allergy and other potential detrimental effects on health are also summarized. To conclude, the results from the human intervention trials are discussed in relation to health and wellbeing.