Free radicals have acquired growing importance in the fields of biology and medicine. They are produced during many different endogenous and exogenous processes. Mitochondria are the main source of endogenous reactive oxygen species (ROS) produced at cell level. The overproduction of free radicals can damage macromolecules such as nucleic acids, proteins and lipids. This leads to tissue damage in various chronic and degenerative diseases. Antioxidants play a crucial role in the body’s defense against free radicals. This review concerns the main properties of free radicals, their sources and deleterious effects. It highlights the potential role of the dietary supplementation of antioxidants and discusses unsolved problems regarding antioxidant supplements in the prevention and therapy of diseases.

Donkey's milk is the best substitute of human milk for its content in lactose, proteins, minerals, and omega-3 fatty acids. Here, we have evaluated the effects of colostrum and milk from donkeys (Martina Franca breed) on the function of human peripheral blood mononuclear cells (PBMCs) at different intervals from lactation. Colostrum induced more IgA responses, while milk induced predominantly more IgG responses. Both milk and colostrum induced expression of CD25 and CD69 on PBMCs. The ability to induce release of interleukins (IL) (IL-12, IL-1 beta and IL-10) and tumor necrosis factor-alpha was confined only to milk, while colostrum was devoid of this capacity. Finally, both colostrum and milk induced nitric oxide (NO) release from PBMCs but milk exhibited a greater capacity than colostrum in NO generation. Taken together, these immunological activities exerted by both colostrum and milk from donkeys may be useful in the treatment of human immune-related diseases. In particular, NO induction by donkey's milk may be very useful in the prevention of atherosclerosis, being a strong vasodilator and an effective antimicrobial agent since pathogens and/or their products may play a proatherogenic role.

Background and aimsMilk contains numerous nutrients. The content of n-3 fatty acids, the n-6/n-3 ratio, and short- and medium-chain fatty acids may promote positive health effects. In Western societies, cow’s milk fat is perceived as a risk factor for health because it is a source of a high fraction of saturated fatty acids. Recently, there has been increasing interest in donkey’s milk. In this work, the fat and energetic value and acidic composition of donkey’s milk, with reference to human nutrition, and their variations during lactation, were investigated. We also discuss the implications of the acidic profile of donkey’s milk on human nutrition.MethodsIndividual milk samples from lactating jennies were collected 15, 30, 45, 60, 90, 120, 150, 180 and 210days after foaling, for the analysis of fat, proteins and lactose, which was achieved using an infrared milk analyser, and fatty acids composition by gas chromatography.ResultsThe donkey’s milk was characterised by low fat and energetic (1719.2kJ·kg-1) values, a high polyunsaturated fatty acids (PUFA) content of mainly α-linolenic acid (ALA) and linoleic acid (LA), a low n-6 to n-3 FA ratio or LA/ALA ratio, and advantageous values of atherogenic and thrombogenic indices. Among the minor PUFA, docosahesaenoic (DHA), eicosapentanoic (EPA), and arachidonic (AA) acids were present in very small amounts (<1%). In addition, the AA/EPA ratio was low (0.18). The fat and energetic values decreased (P < 0.01) during lactation.The fatty acid patterns were affected by the lactation stage and showed a decrease (P < 0.01) in saturated fatty acids content and an increase (P < 0.01) in the unsaturated fatty acids content. The n-6 to n-3 ratio and the LA/ALA ratio were approximately 2:1, with values <1 during the last period of lactation, suggesting the more optimal use of milk during this period.ConclusionsThe high level of unsaturated/saturated fatty acids and PUFA-n3 content and the low n-6/n-3 ratio suggest the use of donkey’s milk as a functional food for human nutrition and its potential utilisation for infant nutrition as well as adult diets, particular for the elderly.

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