The Truth About Soya Protein
When you hear the word “protein”, what is the first thing that crosses your mind? Most people would associate protein with foods like chicken, beef or fish and how it functions to build our muscles. But protein is so much more than that. Protein is the building blocks of life! In fact, protein is the second most abundant compound in the body after water. It is a type of macronutrient that is essential at every stage of life and serves many important roles in our body.
For example, receiving enough protein during infancy and childhood ensures child’s healthy growth and development. Protein also plays a role in maintaining numerous vital functions. It allows key chemical reactions to take place within the body, replace or repair old or damaged cells or tissues, build structural tissues and support immune health. And true enough, protein is essential in building muscle mass. Even as we age, protein continues to be important in maintaining our muscle mass and strength so that we can stay active. Indeed, starting in early 40s, we may begin to experience a gradual, progressive loss of muscle mass and function if we fail to sustain our optimum protein intake.
Interestingly, despite the important roles that protein play, the Herbalife Nutrition Asia Pacific Nutrition Myths Survey 2020, indicated that up to 37% of Malaysians believe that our body requires less protein as we grow older. This shows that many still have mixed misconceptions about protein. This article aims to shed light on protein, especially concerning soya, which is also a substantial source of protein in our diet.
Protein: it’s not just meat
Our body does not store protein like how it can store fats and carbohydrates. Excess protein is converted into fat or excreted from the body. Thus, protein needs to be constantly supplied from dietary sources, through consumption of foods containing protein.
However, it was found that the overall prevalence of Malaysian adults meeting the recommended protein intake was only 40.4% of the population (Nur Azna et al., 2015). This means that more than half of the population does not consume enough protein in their diet.
Moreover, when talking about protein in the diet, most people tend to focus only on animal sources, such as beef, mutton, poultry, fish, eggs and cow milk. In truth, the Malaysia Dietary Guideline actually also encourages the consumption of protein from plant sources, such as legumes. Soya bean and products are legumes!
The goodness of soya
One such source of plant-based protein is soya protein. Soya protein refers to the protein that is found in soya beans and its numerous products, e.g. tofu, tempe, soya milk, soya protein powder, etc. Interestingly, the Nutrition Myths Survey 2020 also indicated that 47% of Malaysians believe that protein powder is not a healthy source of protein compared to protein found in natural foods. Depending on the needs of an individual, soya protein powder can also be a good option if derived from high quality sources.
Soya protein is a high quality and complete protein that can provide all the essential amino acids (what proteins are made of) that our body needs. The good thing about soya protein is that it is packed with a phytonutrient called isoflavones, which has potential antioxidant, anti-inflammatory, and anti-cancer properties.
Soya protein also contains both soluble and insoluble fibre, has no cholesterol and is low in saturated fat. On top of that, it is also a good source of iron, potassium, zinc, omega-3 and omega-6 fatty acids, as well as B vitamins.
Soya protein also serves as the perfect protein source for vegetarians and vegans in helping them to meet their protein needs and gain health benefits of protein. For those who are lactose intolerance or allergic to cow’s milk, calcium-fortified soya milk and its products are a good milk alternative to include in their diet. A clinical study on calcium absorption from tempe compared to milk using dual stable isotopes technique among Malay postmenopausal women showed that calcium absorption from tempe (36.9%) did not differ significantly from milk (34.3%).Tempe may provide readily available calcium for this population of women at risk for low bone mass (Haron et al 2010).
Moreover, soya protein has been shown to provide various potential health benefits. Adding soya protein to diet benefits the heart health and grants protective properties against cardiovascular diseases by lowering low-density lipoproteins and increasing high-density lipoproteins (Messina, 2016; Tokede et al., 2015; Montgomery, 2003).
Soya-based foods have also been found to provide high-quality protein and easily-absorbed calcium, and this contributes to bone health (Messina, 2016). The consumption of soya protein also improves body weight and body composition (Speaker et al., 2018).
Debunking the soya myths
Unfortunately, soya is often the target of unfounded myths, which may discourage people from consuming soya protein, even though it has been the staple in our region for centuries. Let’s see what those myths are and learn the truths behind each of them.
- Myth: All soya products are made from genetically-modified organisms (GMOs).
Fact: Not all soya products are made from GMOs. Various non-GMO tofu, tempe and soya milk are widely available in the market. And even if the product has GMO-origin, there is currently no clear evidence that eating GMO soybeans or products would have any adverse health effects. - Myth: Eating soya increases the risk of breast cancer.
Fact: This saying came from the belief that isoflavones (plant estrogens) found in soy can increase the risk of cancer. Studies have shown that soya isoflavones, regardless of the source, do not exert any harmful effect on breast tissues (Khan et al., 2012; Shike et al., 2014; Hooper et al., 2010). On the contrary, high intake of soya may actually decrease the risk of breast cancer. A prospective study on 300,000 Chinese women and meta-analysis of dose-response showed that a higher soya intake may in fact provide considerable benefits for the prevention of breast cancer (Wei et al., 2020). - Myth: Soya phytoestrogens inhibit thyroid function
Fact: Various studies and comprehensive reviews have actually showed that neither soya foods nor isoflavones have any adverse effect on thyroid function in men or women with normal thyroid gland function (Messina & Redmond, 2006; Ryan-Borchers et al., 2008; Bitto et al., 2010). Plus, European Food Safety Authority has also concluded that isoflavones do not adversely affect the breast, thyroid or uterus functions of postmenopausal women. - Myth: Soya causes men to be more feminine.
Fact: Be assured that this is just a baseless assumption. Soya contains a phytonutrient called soy isoflavones. Extensive reviews have indicated that consumption of soya proteins or isoflavones has shown no effect on male reproductive hormone levels in the body (Hamilton-Reeves et al., 2010).
As a final note, it has to be stressed again that soya and soya products are good sources of complete protein. They are packed with diverse nutrients and should be included as part of our healthy diet. Even though some myths about soya are prevalent, the quoted evidence is often relatively weak compared to the numerous credible studies on the benefits of soya. The fact is soya has been part of our diet since a long time ago and proven to be safe for consumption for most people.
Article by Assoc Prof Dr Hasnah Haron, Nutritionist, Nutrition Society of Malaysia
