The recommended amount of soy consumption per day is a controversial issue. Different studies and organizations recommend different amounts. Should we avoid soy altogether? Or perhaps a little bit of soy is good for you? Or can we consume as much as we would like? How much soy is too much?
To find the answers watch this 2-minute video from NutritionFacts.org:
What is one serving of soy? 
Soy yogurt – 1 cup
Tofu – 3 ounces
Soymilk – 1 cup
Edamame – 1/2 cup
Soy “burger” – 1 patty
Tempeh – 3 ounces
Soy pasta – 1/2 cup (cooked)
Soy nutrition bar – 1 bar
Soy nuts, roasted – 1/4 cup
Soy breakfast patty – 2 patties
Meatless soy crumbles – 1/3 cup
Soy chips – 1 bag
Soy nut butter – 2 Tbsp
Video courtesy of Dr. Michael Greger and NutritionFacts.org.
 Shu XO, Zheng Y, Cai H, Gu K, Chen Z, Zheng W, Lu W. Soy food intake and breast cancer survival. JAMA. 2009 Dec 9;302(22):2437-43.
 Wu AH, Yu MC, Tseng CC, Pike MC. Epidemiology of soy exposures and breast cancer risk. Br J Cancer. 2008 Jan 15;98(1):9-14.
 Nagata C, Shimizu H, Takami R, Hayashi M, Takeda N, Yasuda K. Dietary soy and fats in relation to serum insulin-like growth factor-1 and insulin-like growth factor-binding protein-3 levels in premenopausal Japanese women. Nutr Cancer. 2003;45(2):185-9.
 Dewell A, Weidner G, Sumner MD, Barnard RJ, Marlin RO, Daubenmier JJ, Chi C, Carroll PR, Ornish D. Relationship of dietary protein and soy isoflavones to serum IGF-1 and IGF binding proteins in the Prostate Cancer Lifestyle Trial. Nutr Cancer. 2007;58(1):35-42.
 Arjmandi BH, Khalil DA, Smith BJ, Lucas EA, Juma S, Payton ME, Wild RA. Soy protein has a greater effect on bone in postmenopausal women not on hormone replacement therapy, as evidenced by reducing bone resorption and urinary calcium excretion. J Clin Endocrinol Metab. 2003 Mar;88(3):1048-54.
 Maskarinec G, Takata Y, Murphy SP, Franke AA, Kaaks R. Insulin-like growth factor-1 and binding protein-3 in a 2-year soya intervention among premenopausal women. Br J Nutr. 2005 Sep;94(3):362-7.