The Dietitian’s Guide to Vegetarian Diets by Reed Mangels & Virginia Messina & Mark Messina

Author:Reed Mangels & Virginia Messina & Mark Messina [Mangels, Reed & Messina, Virginia & Messina, Mark]
Language: eng
Format: epub
Publisher: Jones & Bartlett Learning Publishers
Published: 2011-12-14T22:00:00+00:00

ASIAN SOY INTAKE

The lower rates of certain chronic diseases in soyfood-consuming countries20,21 contributed to the initial enthusiasm for investigating the role of soy in reducing chronic disease risk.22 Consequently, Asian soyfood intake can serve as one guide for Western intake. Unfortunately, estimates of Asian soy intake have frequently been misrepresented in both the online and print media. There is no reason for any confusion or misunderstanding regarding this issue because intake data are widely available in the peer-reviewed literature. These data come from studies in which validated food frequency questionnaires designed to comprehensively assess soy intake were administered to thousands of individuals.

A comprehensive review7 published in 2006 that included five studies involving older adults in Japan,23–27 found soy protein intake in women ranged from a low of 6.0 g/d26 to a high of 10.5 g/d,25 whereas the range in men was 8.0 g/d27 to 11.3 g/d.25 Soyfoods contributed from 6.526–12.8%25 of total protein intake. These data are consistent with a large amount of more recently published data.28–31 Survey data also indicate that mean isoflavone intake ranges from about 25 to 50 mg/d.7,28–30 For comparison, one serving of a traditional soyfood provides anywhere from about 7 g (1 cup soymilk) to as much as 15 g (3 to 4 ounces of some types of tofu) protein per serving.

Interestingly, according to food disappearance data from the Food and Agricultural Organization, per capita soy protein intake has remained constant during the past 40 years in Japan. However, as a percentage of total protein intake, it has decreased from about 13% to 10%.7 This is because of the increased protein content (mostly from animal sources) of the Japanese diet. Because soy intake is decreasing among younger Japanese, absolute per capita intake may slowly begin to decline.

In comparison to Japan, soy intake of Hong Kong is about only half as much.32 Korean intake appears to be between that of Japan and Hong Kong.33 In mainland China, estimating intake is more difficult because the population has a very heterogeneous dietary behavior varying according to geographic region. There are excellent data from Shanghai, however, where soy intake appears to be higher than in other parts of China. The Shanghai Men’s Health Study (SMHS) and the Shanghai Women’s Health Study (SHWS) are prospective epidemiologic studies each involving approximately 50,000 subjects.34–36 These studies indicate that daily mean soy protein and isoflavone intakes are similar to Japan34,35 or somewhat higher.36 For example, in the SMHS, for soy protein and isoflavones, the mean ± standard error of the mean were 12.5 and 7.94 g/d, respectively, and 36.2 and 24.4 mg/d, respectively.36

There are also excellent data on the upper range of soy intake in Shanghai. In a report from the SHWS, about 10% of women reportedly consumed about 20 g of soy protein and about 85 mg/d isoflavones, whereas about 2% consumed ≥25 g/d soy protein (mean isoflavone intake in this group was 145 mg/d).34 In another report from Shanghai, among those women consuming a more plant- rather than meat-based diet, fourth quartile soy protein intake was 17 g/d.

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