Oxidative stress is caused by an imbalance between the production of reactive oxygen (free radicals) and the body's ability (antioxidant capacity measured in ORAC) to readily detoxify the reactive intermediates or easily repair the resulting damage.
The Mediterranean diet is characterized by daily intake of fruit, vegetables, and cereals (whole grain bread, pasta, brown rice, etc), beans, nuts, and seeds; a low-to-moderate intake of dairy products, fish, poultry and wine; a low intake of red meat; consuming egg 4 or less times a week; and olive oil as an important source of fat. These foods are associated with improvements in the total antioxidant capacity of individuals and reduced incidence of diseases related to oxidation.
The Mediterranean diet isn't a quick fix diet for weight loss. Rather it's a healthy way of eating that can help everyone live a longer life and lower the risk of heart disease and other conditions associated with metabolic syndrome. One of the advantages of the Mediterranean diet is iron absorption as non-heme iron (from the fruits and vegetables) rather than heme-iron from saturated fats and meat. Heme-iron which has high bioavailability can act as a pro-oxidant factor known to induce oxidative stress, either by generating reactive oxygen species (free radicals causing inflammation) or by inhibiting antioxidant systems.
However, it is not known whether an increase in dietary iron intake alone leads to increased oxidative stress in healthy individuals. So, Marta Romeu and her colleagues at Faculty of Medicine and Health Sciences, Universitat Rovira i Virgili, Spain, investigated how iron in the diet influenced oxidative stress in Mediterranean population.
The researchers studied 815 healthy individuals (425 women and 390 men) from the northeastern Mediterranean region of Spain. The participants were in the age group of 18 to 77 years. They underwent a clinical interview and data on lifestyle variables were collected. Diet was evaluated using the estimated food record method over 3 non-consecutive days.
The researchers found that men had a higher energy intake and therefore higher consumption of most of the nutrients studied than women; however, no gender difference was found in the consumption of fruit and vegetables. On the other hand, body iron levels were higher in men than in women, because of higher energy intake, no blood loss through menstruation and hormonal factors.
The findings regarding oxidative stress, antioxidant capacity and dietary iron intake revealed the following -
• Oxidative stress is positively associated with aging, but antioxidant capacity is not. Oxidative stress increased with age although no significant differences between the sexes were found.
• Vitamin C intake improve antioxidant capacity, whereas saturated fatty acids caused oxidative stress. An increase in the consumption of vegetables is associated with improved antioxidant capacity, but only in women and not in men.
• In men, age, tobacco and heme iron (saturated fats and meat) are positively associated with oxidative stress.
• Dietary non-heme iron from fruits and vegetables are protective against oxidation while dietary heme iron from meat and fish and saturated fatty acids are associated with increased oxidative stress.
The researchers concluded - 'It is evident from this study that oxidative stress is related to aging regardless of sex, but no alteration in antioxidant capacity is related to age. Moreover, we observed an association between diet and biochemical iron levels with the antioxidant and pro-oxidant status of the organism in our general population'.
Source: http://www.nutritionj.com/content/pdf/1475-2891-12-102.pdf
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