Samples of 11 different brands of commercially available soy-based beverages (n = 65), including products made from soy protein isolate (SPI) and soy milk, mixed with fruit juice and/or flavoring, were analyzed for their isoflavone content and in vitro antioxidant activity. There was a large variation in isoflavone and total phenolics contents ranging from 0.7 to 13 mg of isoflavones/200 mL and from 6 to 155 mg equivalents of catechin/200 mL, respectively. The antioxidant activity also varied significantly among products. Storage of the beverages at room temperature caused a significant decrease of antioxidant capacity, soluble phenolics, and isoflavone contents after 9 months. When soybeans used for beverage production were stored for up to 6 months in silos, the resulting products were not affected. However, a decrease of malonyl and a proportional increase of free glucosidic forms of isoflavones were observed after storage of both the raw material and the beverages.

Soybean is the most important source of isoflavones, which have been associated with beneficial effects in humans, including prevention of cancer, cardiovascular diseases, osteoporosis and relief of menopausal symptoms. Soybean consumption in Brazil is not as significant as in Asian countries and in this context, soy beverages could be a way to include these bioactive substances in ocidental diet. However, studies about isoflavone content in these products are scarce, which accounts for the present work. Samples of 12 different brands of commercially available soy milk drinks (n = 65), including products made from isolated soy protein and soymilk mixed with fruit juices and/or containing flavoring ingredients were analysed for their isoflavone content and profile using highperformance liquid chromatography. The antioxidant activity was measured using 2.2diphenil-1-picryl-hydrazil (DPPH) free radical method and the total phenolics was determined by Folin-Ciocalteau method. There was a large variation in total isoflavone concentration and total phenolics content among the different brands of soy milks ranging from 0.7 to 4.9 mg isoflavones/200 mL and 6 to 146 mg equivalents of catechin/200 mL of soymilk mixed with fruit juice. For natural or chocolate soy beverages, the isoflavone content varied from 4 to13 mg/200 mL and the total phenolics ranged from 38 to155 mg equivalent of catequina/200 mL. Levels of protein ranged from 0.8 to 6.0 g/200 mL, these values were associated positively with isoflavone content from samples. The β-glycosides were the predominant form of the isoflavones in the products analyzed. The results showed that total isoflavone, phenolic contents and isoflavone profile of soy beverages depends on processing conditions. Also the antioxidant activity varied significantly among products. The results obtained show that the consumption of 300 mL of soy beverage natural flavor would result in an intake of around 20 mg isoflavone, very similar to the Korean daily intake, indicating that soy beverages could represent important sources of isoflavones in our diet. Furthermore, the soluble isoflavone content of soy beverage decreases with the storage time associated with a reduction of the solubility of soy protein. The profile of isoflavones and antioxidant capacity of beverages are also altered.

Background: Oxidative stress (OS) is an important process related to the pathophysiology of rheumatoid arthritis and can be increased by the low intake of antioxidants. Zinc (Zn) is an important antioxidant trace-element for human health and the assessment of the nutritional status of this micronutrient in these patients is of relevance. Aim: This study aimed to evaluate Zn nutritional status in rheumatoid arthritis patients and its relation to OS. Methods: A case–control study was carried out with 51 patients diagnosed with rheumatoid arthritis (RA group) recruited in Hospital São Paulo (São Paulo, Brazil) and 55 healthy women (CO group) from the campus of the University of São Paulo. Blood and 24-hour urine collection were used for biochemical parameters related to Zn status and OS. The assessment of dietary Zn was performed by three 24-hour dietary recalls. Results: The RA group presented significative low Zn intake ( p < 0.001) and plasma concentration ( p = 0.040) of this mineral compared to the CO group. However, both groups were Zn deficient and the disease activity (DAS28 score) for RA patients did not influence Zn biomarkers. In addition, the antioxidant enzymes (superoxide dismutase and glutathione peroxidase) activity and the urinary 8-isoprostanes were reduced in RA patients. Conclusion: The evaluation of dietary intake and biochemical biomarkers indicates that rheumatoid arthritis patients are zinc deficient and have increased OS.