Soy and Tofu

Soy and tofu products include soybeans (edamame), soy nuts, tofu, fermented products like tempeh and miso, and soy/tofu-based products (like soy milk, mock meats, etc.).

Quick Page Summary: As long as it's eaten in moderation, soy and tofu products can be extremely healthy and nutritious for you. Although it's still being debated whether non-fermented soy and tofu products contain harmful toxins, most experts generally agree that the health benefits probably outweigh any dangers.

Moderation

There are numerous, tasty, soy/tofu-based meat and dairy alternatives available these days, and it's easy to focus your diet on these alternatives—especially if you're transitioning from a meat-based diet that focused on protein as the main dish. Not only is this unnecessary, it can be very unhealthy. Remember that, like anything, moderation and variety is best. No diet should focus on soy/tofu products; healthy diets should focus on the new four food groups, which include whole grains, fruits and vegetables, and beans/legumes. Small amounts of soy/tofu added to an already healthy veg diet may be beneficial to your health; just be careful not to overdo it.

Controversies

We've all heard lots of hype about how good soy is for you. Some of the latest studies suggest that soy products may reduce the risk of heart disease, lower blood pressure in patients with hypertension, help reduce the risk of osteoporosis, improve memory, decrease menopausal symptoms, reduce the risk of some cancers, and assist in body weight control. Soy and tofu products can also be very nutritious.

Despite pro-soy studies, there's a lot of controversy about whether soy/tofu products might actually be unhealthy for you. Please do your own research and to come to your own conclusions. In the meantime, the current consensus seems to be that the benefits probably outweigh any dangers when eaten in moderation with a healthy veg diet.

"I'm aware of Internet paranoia on the subject of soy and the contention that only fermented soy is safe to consume. That is simply not true. Some of the best forms of soy - edamame, tofu and soy nuts - are unfermented and are much more likely to help you than hurt you. [..] All told, based on the evidence to date, I see no reason to worry about eating soy foods, whether fermented or not. I still recommend consuming one to two servings of soy per day, an amount equivalent to one cup of soy milk, or one half cup of tofu, soy protein (tempeh) or soy nuts." — Dr. Andrew Weil, M.D. in "Rethinking Soy"

Here's an overview of some of the issues being debated:

• Soy products are known to inhibit the absorption of iron to a significant extent. Although soy products can meet the RDA amount of iron, the amount that is absorbed may be insufficient. Additional vitamin C may improve uptake of iron.

• Soy has many potential anti-nutrient effects. There are a number of components present in soybeans that exert a negative impact on the nutritional quality of the protein. Other diverse but ill-defined factors appear to increase the requirements for vitamins A, B12, D, and E.

• Scientists generally agree that grain and legume diets high in phytates contribute to widespread mineral deficiencies in third-world countries. The soybean contains more phytate than any other grain or legume studied.
  
  Cooking does reduce phytate contents; however, soy seems highly resistant to these cooking techniques. Fermentation to produce products like tempeh and miso does reduce phytate contents significantly. Tofu and bean curd remain high in phytate, as do TVP (textured vegetable protein) products.
  
  The phytate content remains in soy milk to block the uptake of essential minerals. The alkaline solution that is used to soak the soy milk solution produces a carcinogen, lysinealine...

• Tofu is a mixture of soybean curd and plaster of paris. It has a high phytate content and may contain traces of other toxins used in its manufacture. Tofu does contain the highest quantity of isoflavones and phytoestrogens, which are said to inhibit tumor formation and prevent hormone-related diseases in women.

• TVP (textured vegetable protein) is the result of taking soy protein isolate and applying a high-temperature and high-pressure extrusion process. Usually artificial flavors, such as MSG, are added to mask the beany flavor of TVP. By the time TVP products are cooked, they've usually reached their third or fourth heating.

• Isoflavone aglycones are anti-carcinogenic substances found in traditionally fermented soy products. In modern, non-fermented soy products, such as tofu and soy milk, these substances are present as beta-glycoside conjugates that do not have anti-carcinogenic effects.

• The fatty acids that are alleged to be beneficial in soy products, the essential omega-3 fatty acids, are particularly subject to rancidity during high temperature and pressure processing. The fats then become trans-fats and form carcinogenic compounds. Trans fats, also found in vegetable margarines, are very unhealthy.

• Hexane or other solvents are used to extract oil from soybeans. Traces of this remain in commercial soy products. It's suspected that this group of chemicals may be linked to parkinsonism.

Resources

For information about soy and tofu products, visit these resources:

• "Is Soy Safe?" by Jack Norris, RD
• "Is It Safe to Eat Soy?" by Virginia Messina, MS, RD and Mark Messina, PhD
• "Is It True What They Say About Soy?" from the UC Berkeley Wellness Letter, November 2002.
• "Q&A: Rethinking Soy" by Andrew Weil, M.D. Posted March 12, 2004.
• "Soy and Your Health" by Physician's Committee for Responsible Medicine (PCRM)
• "The Soy Connection," A publication of the soy industry, edited by Mark Messina, PhD.
• "Soy: The Hopes Probably Outweigh the Fears" by John Livesay PhD, Scientific Officer, Department of Endocrinology, Christchurch Hospital, New Zealand.
• Syd Baumels's Review of "The Whole Soy Story: The Dark Side of America's Favorite Health Food" by Kaayla T. Daniel. Posted December, 2006.
• "Understanding Soy Foods" by NutritionMD.org