The health benefits of barley are widely well known.

Most people associate whole food grains with being healthy grains, and they are right to do so! One reason why barley is considered one of the healthiest whole food grains is because it is high in starch, specifically resistant starch. Barley is composed of up to 18.2% resistant starch, in comparison to grains like wheat (13.6%), white rice (14.1%) and oats (7.2%). Our bodies are unable to digest resistant starch, so it ferments in the colon, producing fatty acids that can decrease the risk of colon cancer and acts as a prebiotic for our important gut bacteria (Farag et al., 2020).

Other health benefits of consuming barley include a reduced risk of breast cancer, type 2 diabetes, childhood asthma, and other benefits written about in an previous blog post (see

What happens if your favourite whole grain products use the barley by-product of the beer brewing process, known as brewers’ spent grain, instead of regular barley? Does the fact that brewers’ spent grain is a by-product mean that it is less nutritious for you than regular barley?

Brewers’ spent grain (or BSG for short), is the most common by-product of the brewing industry, making up about 85% of the by-products produced in the brewing process (see Figure 1). On average, for every 100L of beer produced, approximately 20kg of BSG by-product will also be produced (Mussatto et al., 2006). Up until recently, this by-product has mainly been used as animal feed or has gone to landfill; however, research is showing that there is a lot of potential for BSG to be used in human food products due to its nutritional content and potential health benefits (Lynch et al., 2016).

BSG is an abundant source of protein and fibre. More specifically, it is glutamine-rich and high in non-cellulosic polysaccharides, both of which serve to improve digestion. In general, BSG is composed of 20% protein and 70% fibre. Most of the starch present in regular barley is not present in BSG since it is removed during the mashing phase of the brewing process (Mussatto et al., 2006), as depicted in Figure 1. On average, the BSG produced at the end of the brewing process accounts for 31% of the original malt weight (Mussatto et al., 2006). This means that the protein and fibre present in barley will be more concentrated in the BSG by-product, as seen by the higher percent composition of protein and fibre in BSG displayed in Figure 2.

Figure 2 Comparison between barley and dry brewers’ spent grain (BSG) composition of protein, total dietary fibre, starch, and lipids

Protein (%)10 – 20115 – 302  
Total Dietary Fibre (g per 100 g dry material %w/w)10 – 283  22 – 802  
Starch (%)60 – 704  3 – 122
Lipids (%)2 – 3 (found most abundant in endosperm)13 – 62  
Figure sources: 1Farag et al. (2020); 2Lynch et al. (2016); 3Prasadi & Joye (2020); 4Asare et al. (2011) as cited in Zhu (2017)

Figure 2 shows a comparison between barley and BSG when looking at protein, total dietary fibre, starch and lipids. The range presented is based on variations within research studies, which all display the trend that BSG’s composition has a greater percentage of protein and fibre than regular barley, and regular barley has a greater percentage of starch than BSG. These differences in percent composition between barley and BSG are due to the brewing process, which removes most of the starch present in the original barley, leaving the BSG with a higher proportion of fibre and protein than its barley counterparts (Mussatto et al., 2006). There is no new protein and fibre being created in the brewing process, but the existing protein and fibre in the original barley becomes more concentrated in the BSG by-product, accounting for the higher percent composition values seen in Figures 2 and 3.

Figure 3 Protein profile of barley vs. brewers’ spent grain (BSG), as a percentage of total protein

Some essential amino acids present
Some non-essential amino acids present
Glutamic acid0.8516.59
Aspartic acid0.194.81
Source: (Waters et al., 2012, as cited in Lynch et al., 2016)

Figure 3 shows a protein profile of barley and BSG. Essential amino acids are the those which our bodies are not able to make (so we need to get them through our diets) and non-essential amino acids are those which can be made by our bodies. Highlighted in Figure 3 is the fact that the essential amino acid lysine and the non-essential amino acids histidine and glutamic acid are significantly higher in BSG in comparison to regular barley as a percentage of total protein.

Research into BSG being used in breads has shown that BSG helps to improve the bread’s nutritional value;

Mussatto et al. (2006) observed that the protein content of bread made with 10% BSG increased by 50% and the fibre content doubled, in comparison to bread that was not made with BSG. In addition to increasing the protein and fibre content, using BSG flour in foods was also found to provide important minerals, such as calcium, iron, zinc and magnesium (Mussatto et al., 2006).

So what does this all mean? Research has shown the wide range of benefits whole grains, like barley, can have on human health. It turns out, BSG has similar health benefits and is composed of a higher proportion of protein and fibre than barley. BSG is considered an “ideal ingredient” (Ikram et al., 2017) to add to human foods; it is readily available, rich in nutrients and able to increase the fibre and protein content while minimizing calories present, in foods such as bread, biscuits, muffins and other snacks (Ikram et al., 2017).

While BSG may no longer be useful in beer manufacturing , it is useful for producing high quality, nutritious food products.

Researched and written by Gillian Whorms

Nutritional benefits of Spent Grains