Getting Antioxidants We Need from Fruits and Vegetables
To counteract the severe oxidative stress created with the production of O2 during photosynthesis, plants load themselves with antioxidants. Antioxidants commonly found in fruits and vegetables are beta-carotene, lutein, lycopene, selenium, vitamin A, vitamin C, and vitamin E. Eating a diet with lots of vegetables and fruits is healthy for humans.
Processing can also affect the bioavailability of antioxidants found in food. Because most of the compounds are unstable, exposure to oxygen or heat treatment (blanching, cooking, pasteurization, sterilization, dehydration and freezing) can lead to a significant loss of natural antioxidants. Enzymes can be used to release vitamins and antioxidant-rich compounds from fruit to improve the antioxidant content of juices.
Because dietary intakes do not accurately reflect the amount of food consumed or bioavailability of antioxidants in the food, it is not surprising that self-reported intake of fruits and vegetables does not correlate well with cardiovascular health. Serum antioxidant levels (carotenoids and tocopherols) are more objective measures of nutritional status, factoring both dietary intake and bioavailability. Measuring baseline carotenoid and tocopherol concentrations in 4,810 young adults (average age of 25y), Odegaard and colleagues reported higher α-tocopherol and carotenoid blood concentrations were associated with lower CVD risk over the subsequent 25y. Of course, it is debatable if a single blood sample is reflective of 25y of living. Nevertheless, one cannot argue that serum antioxidant concentrations are better predictors of nutritional status and CVD risk than dietary intake.
For more information on the antioxidant content of foods, see Carlsen and colleagues publication.
Odegaard AO, Jacobs DR, Steffen LM, Van Horn L, Shikany JM, Gross MD. Serum dietary antioxidants in young adulthood and incident cardiovascular disease in middle age: The CARDIA study. Abst 34. 2014 Circulation 129:A34
Nicoli MC, Anese M, Parpinel M. Influence of processing on the antioxidant properties of fruit and vegetables. 1999 Trends Food Sci Technol doi: 10.1016/S0924-2244(99)00023-0
Miedema MD, Petrone A, Shikany J, Greenland P, Lewis C, Pletcher M, Gaziano JM, Djousse L. The association of fruit and vegetable consumption during early adulthood with the prevalence of coronary artery calcium after 20 years of follow-up: The Coronary Artery Risk Development in Young Adults (CARDIA) study. 2014 J Am Coll Cardiol doi: 10.1016/S0735-1097(14)61350-4
Carlsen MH, Halvorsen BL, Holte K, Bohn SK, Dragland S, Sampson L, Willey C, Senoo H, Umezono Y, Sanada C, Barikmo I, Berhe N, Willett WC, Phillips KM, Jacobs Jr DR, Blomhoff R. The total antioxidant content of more than 3100 foods, beverages, spices, herbs and supplements used worldwide. 2010 Nutr J doi: 10.1186/1475-2891-9-3