Malondialdehyde (MDA) found in the body comes from two sources: food consumed and lipid peroxidation occurring in the tissues. The formation of MDA and the scale and rate of lipid oxidation in the tissues of living organisms is influenced by a number of endo- and exogeneous factors. The products of lipid peroxidation, in particular MDA, exhibit cytotoxic, mutagenic and carcinogenic properties. They can also inhibit enzymes associated with defending cells against oxidative stress. Not only do the occurring processes contribute to the development of many diseases, but they are also a part of the aging process. The body defends itself to some extent against the effects of free radicals by trapping and neutralising them. The main source of antioxidants is food products of plant origin. Lifestyle, the components of which are diet and physical activity, is an important element in preserving health understood as physical and psychological well-being. Dietary habits and a diet rich in antioxidants are modifiable factors which not only prevent age-associated diseases, but also delay aging processes.