Soya sauces, based on fermentation:
A study by National University of Singapore shows that Chinese dark soy sauce contains 10 times theantioxidants of red wine, and can help prevent cardiovascular diseases. (However, it is unlikely to be used in nearly as great a quantity as wine.) Soy sauce is rich in lactic acid bacteria and of excellent anti-allergic potential.
Soy sauce contains ethyl carbamate.
Soy sauce does not contain a level of the beneficial isoflavones associated with other soy products such as tofu or edamame. It can also be very salty, having a salt content of between 14%–18%. Low-sodium soy sauces are produced, but it is difficult to make soy sauce without using some quantity of salt as an antimicrobial agent.
Most varieties of soy sauce contain wheat, to which some people have a medical intolerance.However, some naturally brewed soy sauces made with wheat may be tolerated by people with a specific intolerance to gluten because gluten is not detectable in the finished product. Japanese tamari soy sauce is traditionally wheat-free, and some tamari available commercially today is wheat- and gluten-free.
A 2001 test of various soy sauces and related products by the United Kingdom Food Standards Agency(FSA) found that 22 out of 100 samples contained a substance called 3-MCPD (3-monochloropropane-1,2-diol) at levels considerably higher than those deemed safe by the European Union. About two-thirds of the 22 samples also contained a second chemical called 1,3-DCP (1,3-dichloropropane-2-ol) which experts advise should not be present at any levels in food. Both chemicals are carcinogenic, and 1,3-DCP can cause genetic damage to be passed on to offspring who never consumed the sauces.The FSA recommended that the affected products be withdrawn,and in June 2001 issued a Public Health Advice leaflet warning against a small number of soy sauce products that were found to contain high levels of potentially cancer-causing chemicals. The leaflet singled out brands and products (some by batch numbers) imported from Thailand, China, Hong Kong and Taiwan. Although the leaflet primarily looked at soy sauce, it also included oyster sauce, marinades and other types of sauces, that affected the brands Golden Mountain, King Imperial, Pearl River Bridge, Jammy Chai, Lee Kum Kee, Golden Mark, Kimlan, Golden Swan, Sinsin and Tung Chun. Despite these being small in number in the UK, they are the dominant brands in their respective nations.
In Vietnam 3-MCPD was found in toxic levels (In 2004 the HCM City Institute of Hygiene and Public Health found 33 of 41 sample of soya sauce with high rates of 3-MCPD, including six samples with 11,000 to 18,000 times more 3-MPCD than permitted, compared to about 5,000 times in 2001) in soy sauces there in 2007, along with formaldehyde in the national dish Pho, and banned pesticides in vegetables and fruits. A prominent newspaper Thanh Nien Daily commented: "Health agencies have known that Vietnamese soy sauce, the country's second most popular sauce after fish sauce, has been chock-full of cancer agents since at least 2001."