Heat water and milk until warm (100° to 110°F) and pour into large mixer bowl. Add yeast and let rest 5 minutes. Add honey, oil, salt, vital wheat gluten and whole wheat flour; beat for 2 minutes with electric mixer. Add flax seed and bread flour, 1 cup at a time until soft dough forms. Knead on lightly floured surface for 5 to 8 minutes. Place in a greased bowl, turning to coat. Cover and let rise in a warm, draft-free place about 1-1/4 hours, until doubled. Punch dough down; divide in half. Divide one dough portion into 3 equal pieces, rolling each into a 16-inch rope. Place each rope onto a separate sheet of aluminum foil or waxed paper. Brush each rope with the egg mixture; sprinkle or roll one rope with half of the sunflower seeds, another with half of the sesame seeds and the third with half of the poppy seeds. Place ropes on a greased baking sheet. Pinch ends together at one end to seal. Braid ropes; pinch ends to seal. Repeat with second half of the dough. Cover and let rise 45 minutes or until almost doubled.
Bake in preheated 350°F oven for 35 to 40 minutes. Cool on a wire rack.