All Hail To Soya

organic soya beans displayed on a wooden table with a spoon, bowl and other strange container.
Soya beans. Photo by KEKO64, courtesy of

Soya or just soy (Glycine max. L.) has developed into one of the most important nutritional foods throughout the world with strong health benefits.  It has been known for much longer by people in the Far East who were eating it for many centuries. Not surprisingly it attracted the attention of Western nations in the 70’s, who began to use soy sauce in Chinese cuisine, to replace meat with a vegetarian equivalent based on soy, or simply eat it as a health food.

Soya beans and soya milk. Copyright: seagames50 / 123RF Stock Photo
Soya beans and soya milk. Copyright: seagames50 / 123RF Stock Photo

The Growth Of Soya as a Food, Ingredient And Health Product 

Commercially, the sales of soya in both food and beverage was reported to be $1.4 billion which is a 15% increase since reported figures in 2003. One particular product type, the soya milks has grown over 60% in 5 years to 2008 with continuing growth. The other major soy segment are the snack bars which have developed with increasing prominence as meal replacement foods (Heyl-Rushmer, 2009).

The FDA (1999) then stated that 25g of soybean protein per day was useful for preventing cardiovascular disease (CVDs) based on the evidence for a reduction of low-density lipoprotein cholesterol (LDLs) in hypercholesterolemic subjects. Once the FDA in the States had approved this critical health claim, it started to become a serious food, especially for vegetarians and milk-intolerant consumers. However, the claim is being reassessed in the light of controversial evidence which disputes these findings.

 Those affected by coeliac disease prefer the isolates and concentrates by making excellent functional ingredients.

There is a plethora of nutritional evidence associated now with soya, the beans and its derivative products, soy protein isolates and concentrates, soybean oil, soy milk, defatted flour, as textured protein and tofu.  Soy lecithin is a highly valued emulsifier for oil and lipid preparations so it also brings useful functional benefits. Soya beans are legumes that are high in fibre, minerals such as potassium and vitamins such as folate. Soya protein contains all the essential amino acids, making it complete. Soybeans also contain some key lipids such as various omega-3 fatty acids and in particular alpha-linolenic acid (ALA). It’s worth noting that the highest content of this important fatty acid is found in flaxseed oil.

Compounds In Soya 

The most important componentry appears to be:-

♦ Saponins

♦ Isoflavones (acting as antioxidants) such as genistein and diadzein.

♦ Phytosterols

As a protein, it has no real benefit over whey or casein except for its amino-acid profile which might be more attractive to those seeking a more balanced intake. Most athletes for example prefer this protein because of its high glutamine, branched chain amino acid profile (BCAA) and arginine content.  There is still considerable research to be conducted on finding ways and means to reduce the undesirable off-notes which develop if soy is not processed properly. There is also a situation where flavour compounds will bind to the soy protein leading to a reduction in taste impact (Suppavorasatit and Cadwallader, 2010).

The heart related benefit has been linked to its proteins (Lovati et al., 2000; Fukui et al., 2002; Anderson, 2003) especially the alpha subunit of the 7S globulins (Manzoni et al., 2003). At current levels, the average Asian diet contains between 20 to 50 mg isoflavones (Adlercreutz et al., 1991; Nagata et al., 1997) whereas in Western regions the level is about 100 fold lower ranging from 0.15 µg/day to 3 mg/day in the USA. This intake level is starting to rise however.  The isoflavones of interest are derived from the glycosides, genistin and daidzin which are converted to genistein and daidzein in the body (Barnes et al., 1994; Adlercreutz, 1995).  

Fresh soya bean pods. Copyright: maewjpho / 123RF Stock Photo
Fresh soya bean pods. Copyright: maewjpho / 123RF Stock Photo

One of the more intriguing aspects of a soya-rich diet is the potential for a reduction in prostate cancer. Cautiously over many years, epidemiological evidence has been gathered to show an inverse association between soy consumption and prostate cancer risk (Rose et al., 1986; Mills et al., 1989; Shimizu et al., 1991; Giovanucci, 1995). The link is made to the ingestion of soy isoflavones, particularly genistein and a number of mechanisms have been suggested as to how this link might be enacted.

Genistein is now being linked to a reduction in breast cancer formation due to an important interaction with a gene involved in suppressing tumours.


There are a couple of varieties worth noting. The yellow skinned type is more commonly available in stores but the black coated soybean has attracted attention.

Nutritionally,  the black soy beans are virtually the same as the yellow type, though they are higher in some phytonutrients, including various antioxidants. The anthocyanin content is slightly higher in the black variety hence the stronger claims. 

As the 21st Century progresses, the interest in soy as an ingredient continues to excite interest.


Revised 1st November 2017 to reflect the FDA uncertainly about the cardiovascular protective effect of soy. Further information to be provided once the situation is more clearly understood.


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