We would like to thank Carlos Kusano Bucalen Ferrari for taking the time to respond to the Commentary by Violeta Ribeiro (EBN 2002; 5:57). Mr Ferrari gives us an interesting overview of the biochemical effects of several antioxidants in laboratory studies. These kinds of studies are frequently the starting point for developing new drugs and treatments but it is important to emphasise that the results of in vitro studies in laboratories are frequently not replicated when a treatment is trialed in the people the drugs are intended for. Therapies which appear to make sense from a physiological or biochemical perspective are often ineffective or harmful when tried in humans. We would therefore very much agree with the sentiments in the last line of the letter - more studies, and particularly clinical trials, are necessary to provide evidence for the clinical benefit of these therapies.

Professor Nicky Cullum
Centre for Evidence Based Nursing
Department of Health Sciences
University of York
Alcuin Teaching Building
York

Dear Editor

It is well documented that Free radicals (FRs) and their Oxidative Reactions are implicated in more than 70 diseases and disorders [1,2], including inflammatory reactions, such as alergies and rheumatoid arthritis. As FRs and Oxidative stress are also implicated in many cell death processes [3], many scientific activities are being done to discover possible protective effects of the antioxidant therapy [1]. Today, based on Oriental and Mediterranean dietetic studies, we know that many foods,the functionals or nutraceuticals, can improve physiological properties of the human body, improving health and preventing diseases. I should be emphazised that antioxidant activity of foods is one of the most important functional food atributtes.

Persenone A, an avocado compound, was able to inhibit two peroxidative enzymes involved in inflammatory responses, the nitric oxide synthase and cyclooxygenase in mouse macrophages [4]. Murcia et al. [5] demonstrated that avocado possess antioxidant activities as well as many other Mediterranean and Tropical Fruits do. Some years ago, Kikusaki and Nakatani [6] had observed that 12 Ginger compounds have antioxidant activity.

This year, Kim et al. [7] reported that ginger, avocado, carrot, turnip and shimeji mushrooms had higher superoxide radical scavenging activity, suggesting that this phytochemicals can prevent oxidative DNA damage, the first step in cancer carcinogenesis.

It should be noted that in rheumatoid arthritis, there are intensive production of FRs and the antioxidant therapy is very important to control the damaging effects of these substances. As exposed before, Ginger, Avocado and other foods are rich sources of antioxidants with a great potential to be explored in rheumatoid arthritis. However, many more basic and studies are necessary to support a teraphy.

References

(1) Ferrari CKB (1998). Lipid peroxidation in foods and biological systems: General mechanisms and Nutritional and Pathological implications. Rev. Nutr., 11: 3-14 (in portuguese).

(2) Ferrari CKB (2001). Oxidative Stress Pathophysiology: Searching for an Effective Antioxidant Protection. Int. Med. J., 8: 175-84.

(3) Ferrari CKB (2000). Free Radicals, lipid peroxidation and antioxidants: Implications for cancer, cardiovascular, and neurological diseases. Biologia, 55: 581-90.

(4) Kim OK, Murakami A, Takahashi D, Nakamura Y,Torikai K, Kim HW, Ohigashi H (2000). An avocado constituent, persenone A, suppresses expression of inducible forms of nitric oxide synthase and cyclooxygenase in macrophages, and hydrogen peroxide generation in mouse skin. Biosci. Biotechnol. Biochem., 64: 2504-7.

(5) Murcia MA, Jimenez AM, Martinez-Tomé M (2001). Evaluation of the antioxidant properties of Mediterranean and tropical fruits compared with common food additives. J. Food Protect., 64: 2037-46. (6) Kikusaki H, Nakatani N (1993). Antioxidant effect of some Ginger constituents. J. Food Sci., 58: 1407-10. (7) Kim HW, Murakami A, Nakamura Y, Ohigashi H (2002). Screening of edible Japanese plants for suppressive effects on phorbol ester-induced superoxide generation in differentiated HL-60 cells and AS52 cells. Canc. Let., 176:7-16.