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Soya, a healthy alternative to meat?

High in protein, fibre & nutrients, does soy affect human fertility?   2013-04-14

Hailed as a healthy alternative to meat, soy products are said to be an excellent source of protein, fibre and nutrients, coupled with the ability to protect against heart disease and some cancers. Soya may even reduce the risk of osteoporosis and some of the unpleasant symptoms of menopause. As such, soy products are occupying an increasing amount of shelf space in our supermarkets, chosen by people who have made a decision to avoid meat. Yet what is soya and is it really as good as it is made out to be?

What is soya?

Soy comes from the Soya bean, which belongs to the legume family and includes all types of beans, peas and lentils. The bean is the edible seed that comes from the ‘pod bearing’ leguminous plant known as pulses. It has been part of the Asian diet for centuries. Soya contains a high quality source of protein. It is naturally low in fat, rich in fibre and provides essential fatty acids, such as Omega 6 and some Omega 3. It also contains a variety of vitamins and minerals, including Iron, Potassium and Folic Acid. A portion of soya counts towards your 5-a-day. However, with soya added to nearly everything we eat, from pork pies to cakes and confectionary, are we eating too much of it?

Is soya as good as it is made out to be?

The simple answer is that it depends on who you ask. The complexity of this subject has spread confusion and for many people there are a lot of unanswered questions:

  1. Does soya lower LDL (bad) cholesterol levels?
  2. Does it benefit cardiovascular health?
  3. Does it help ease symptoms of the menopause?
  4. Does it lower the chance of developing cancer?
  5. Does it cause fertility problems?
  6. Does soya trigger early or premature puberty?

Boosts your health?

According to the US National Center for Biotechnology Information (NCBI) the evidence that soy lowers the risk of cardiovascular disease is inconsistent. The NCBI quotes the 21 February 2006 issue of the Circulation journal as saying that soy has “little or no effect” on cardiovascular health but that there is evidence of it lowering LDL cholesterol. The NCBI goes on to refer to research that appears to show that there is little evidence of soy playing a “beneficial role” in bone health, cancer “and other health parameters” but it then brings evidence of other studies that indicate that soy “may” benefit human health, including inhibiting the growth of certain cancers and aiding bone density.

According to BreastCancer.org, a 2009 study did not show that soy helped lower the risk of breast cancer however, another study conducted on 5,000 Chinese women diagnosed with breast cancer suggested that a diet rich in soy might help against recurrences rather than worsening their prognosis. Similarly, a 2008 study looked at 24,000 Japanese women and found that those with increased soy Isoflavone levels had a lower chance of getting cancer.

Affects human fertility?

Within the last few years, the UK has seen a vast increase in sales of soya milk. This emergence is especially important to those with an allergy to cows’ milk or who follow a vegan diet. However, what is helpful for people to know is that although this substance is less fattening than cow’s milk, soya contains the organic chemical food substance Isoflavones, which mimics the female hormone oestrogen. There has been some concern raised from studies over the effects of this on infants. Concern has also been expressed as to the effect of the soy Isoflavones on levels of testosterone and semen quality in men, on its influence on early puberty in young girls and on its link to fertility problems in women. Research carried out on rats and hamsters revealed that animals fed on a diet that was high in soy went through early puberty and the results of a study published in the October 2005 issue of Biology of Reproduction linked soy derivatives to altered ovarian function and infertility in mice. Other studies however, seem to contradict these findings. A 2003 report states that there is no definitive evidence that the composition of soya-based infant formula adversely affected the health of infants. This was supported in May 2012 when researchers found no difference in behavioural development between infants who were fed soy formula and those who were given formula milk during the first year of their life.

The NCBI refers to data emerging from studies that shows that there is no link between soy and semen quality in men. Similarly, other studies negate a negative effect of soy milk on infants. The UK Food Standards Agency warns against being alarmist until more studies have been carried out. They continue to advocate soya milk for babies until more results confirm or deny these claims. Similarly, the NHS says that there is “little consensus” on the link between soy and male infertility and that “more human studies are needed to determine if there really is a link”.

Genetically modified (GM) soy

GM soy is created by inserting a gene into the soybean that will make it resistant to the toxic effects of certain herbicides, enabling farmers to spray entire fields with herbicide, killing weeds but not the soybean crop. Critics complain that a plant with an altered immune system, allowing a poison to slip through, by definition cannot be good for us and in fact, stories abound of cancer, infertility and birth malformations in countries such as Argentina, where GM soy crops are widely cultivated and extremely poisonous herbicides, are extensively used.

In the UK, no GM crops are grown commercially but imported GM products, especially soya, are used mainly for animal food but to a lesser extent in human foods. The Department for Environment, Agriculture & Rural Affairs will only consent to the planting of GM crops in the UK or to the release of GM products to the market after a full scientific risk assessment has declared the safety of the product. Furthermore, the consumer can exercise choice and refuse to buy food products that contain GM ingredients. EU rules ensure that all foodstuffs that contain GM ingredients are clearly labeled as such.


What emerges from all the above is that soy is an excellent source of protein, fibre and nutrients and is a healthy alternative to meat. As to the alleged dangers, there is no consensus and more human studies are needed. So what is our advice to you? Eat a balanced diet, not making any one foodstuff the mainstay of your diet and above all, do plenty of exercise.