No food will help you lose weight, not directly. Food doesn't cause you to lose weight. They pack a lot of nutrition, but losing weight is about eating less than you burn, not eating "super foods" or avoiding "fattening" foods.
Here's Sparkpeople's article on Flaxseed: www.sparkpeople.com/resource/nutrition_art
"Super foods" are just foods that pack a healthy nutritional punch. They won't do anything other foods don't. You can eat too much of them, just like any food.