Soy milk has been popular in Asia for thousands of years, and is much more common than cow milk. Are there different health effects? There is a lot of differing information out there, but some recent scholarly reviews help to find some answers.

There’s a terrific 2006 review from the American Heart Association — here is the free PDF file. Unfortunately, the main conclusion shows that earlier 1990’s reports of soy’s cardiovascular health have not been well confirmed by follow up studies, and the average cholesterol improvement was only 3%. The abstract sums it up well:

…In the majority of 22 randomized trials, isolated soy protein with isoflavones, as compared with milk or other proteins, decreased LDL cholesterol concentrations; the average effect was
3%. This reduction is very small relative to the large amount of soy protein tested in these studies, averaging 50 g, about half the usual total daily protein intake. No significant effects on HDL cholesterol, triglycerides, ipoprotein(a), or blood pressure were evident. Among 19 studies of soy isoflavones, the average effect on LDL cholesterol and other lipid risk factors was nil. Soy protein and isoflavones have not been shown to lessen vasomotor symptoms of menopause, and results are mixed with regard to soy’s ability to slow postmenopausal bone loss. The efficacy and safety of soy isoflavones for preventing or treating cancer of the breast, endometrium, and prostate are not established; evidence from clinical trials is meager and cautionary with regard to a possible adverse effect. For this reason, use of isoflavone supplements in food or pills is not recommended. Thus, earlier research indicating that soy protein has clinically important favorable effects as compared with other proteins has not been confirmed…

But, as the article mentions, if you have a high risk diet, then switching your protein intake to soy products (tofu, etc) from cow proteins may be a good idea due to secondary effects of lower saturated fat and higher fiber, vitamins, and minerals. You can read more about the American Heart Association’s most recent (2006) general diet and lifestyle recommendations here (a PDF file)

What About Soy Formula?

This is also a running debate, but there is a recent 2008 review from the American Academy of Pediatrics which helps shed some light. Here is the summary:

1. In term infants, although isolated soy protein-based formulas may be used to provide nutrition for normal growth and development, there are few indications for their use in place of cow milk-based formula. These indications include (a) for infants with galactosemia and hereditary lactase deficiency (rare) and (b) in situations in which a vegetarian diet is preferred.

2. For infants with documented cow milk protein allergy, extensively hydrolyzed protein formula should be considered, because 10% to 14% of these infants will also have a soy protein allergy.

3. Most previously well infants with acute gastroenteritis can be managed after rehydration with continued use of human milk or standard dilutions of cow milkbased formulas. Isolated soy protein-based formulas may be indicated when secondary lactose intolerance occurs.

4. Isolated soy protein-based formula has no advantage over cow milk protein-based formula as a supplement for the breastfed infant, unless the infant has 1 of the indications noted previously.

5. Soy protein-based formulas are not designed for or recommended for preterm infants.

6. The routine use of isolated soy protein-based formula has no proven value in the prevention or management of infantile colic or fussiness.

7. Infants with documented cow milk protein-induced enteropathy or enterocolitis frequently are as sensitive to soy protein and should not be given isolated soy protein-based formula. They should be provided formula derived from hydrolyzed protein or synthetic amino acids.

8. The routine use of isolated soy protein-based formula has no proven value in the prevention of atopic disease in healthy or high-risk infants.

Make Your Own Soy Milk!

There are many very simple machines that allow you to make your own soy milk. I’ve been doing it for a couple years now and I love it. In America, this machine isn’t too common to find in stores, so maybe your best bet is first check the store websites

Preparation is super easy; you simply pour in a tiny cup of soy beans and let soak overnight, then press the button in the morning, and the machine grinds and cooks the beans. Presto, within 10-15 minutes you and your family have fresh milk!