Change from mixed diet to lactovegetarian diet: influence on IgA levels in blood and saliva.

IgA concentrations in human plasma, and whole and parotid saliva were measured before and 3 months after a shift to a lactovegetarian diet in 20 volunteers (four men and 16 women mean age 44 yr, range 27-61). The major dietary trends observed were an increased intake of berries and other fruits, vegetables, and dairy products, and a decreased intake of fish, eggs, and meat; biscuits and buns; sweets; alcoholic beverages; coffee; and tea. The consumption of meat, fish, and eggs decreased to zero, showing that the participants had adopted a lacto-vegetarian diet. There was a decrease in fat, protein, sucrose, and alcohol intake and an increase in total carbohydrate and fiber intake. There was no significant change in energy, retinol equivalent, or zinc intake. Despite this change in diet, no significant changes were observed between the mixed diet period and the vegetarian diet period in IgA in plasma, 253 +/- 52 and 264 +/- 55; whole saliva, 2.5 +/- 0.4 and 2.4 +/- 0.4; or parotid saliva, 0.88 +/- 0.22 and 0.90 +/- 0.20 (mg/100 ml, mean values, 95% confidence interval). Moreover, the diet change did not alter the secretion rate in whole and parotid saliva, the secretion rate of IgA in whole and parotid saliva, or the protein content of whole saliva. However, the protein content of parotid saliva increased significantly. Thus, this major diet change was apparently not drastic enough or sustained long enough to cause a change in IgA levels.