Just how healthy is bread? Expert reveals all
28 January 2021 | Gary Tucker, Technology Specialist
Demand for bread exceeded 50% at one point during the current health crisis, proving it as one of the UK’s favourite staple foods. It’s an important part of the diet for many consumers and contributes many key nutrients including dietary fibre. Having worked with the food industry for over 30 years, in this article I’ll share with you what I’ve learnt about the positive attributes of bread when eaten as part of a balanced diet - specifically the role of wheat fibres in promoting digestive health.
Understanding wheat
Before we delve into how bread impacts our health, it’s first worth understanding a little more about the starting material and main ingredient: wheat flour. Wheat is milled into flour for use in bakery products - such as bread, cake and biscuits - as well as animal feed and for distilling into grain spirits. In the UK, approximately five million tonnes of wheat are currently milled each year for human consumption. Of this, around 85% is grown in the UK (Ref. NABIM) with imports from Canada, Germany, France and the USA making up the remaining 15%.
There are two types of wheat that have different physical characteristics and therefore different end uses. Hard wheat is used for bread (with bread flour accounting for two-thirds of UK flour use), while soft wheat is used for other goods including cakes, biscuits and distilling. Before it’s used, wheat undergoes physical processed to increase its digestibility and palatability. This is achieved by milling the grains into flour, which is mixed with water and made into food products such as bread, cakes, biscuits and pastry.
The benefits and role of bread in the diet
There are many forms of bread consumed in the UK from sandwich bread, soda bread, rolls, baguettes, crumpets, muffins, tortillas, wraps, naan, pizza bases, focaccia through to sweetened breads such as brioche, teacakes and numerous types of buns. With such variety and popularity it’s clear that bread plays a major role in the UK diet, and this was outlined in a recently updated review by the British Nutrition Foundation (BNF), supported by the Federation of Bakers (Ref. Nutrition Bulletin). The review looked at the contribution of bread to nutrient intakes, the biological effects of different components of bread, health claims related to these, and future bread trends. Overall, its fibre content was seen as central to many of its positive attributes.
Energy release
Bread contains beneficial quantities of the three macronutrients: carbohydrate, protein and lipid (fat). Carbohydrates in bread are found in three forms including sugars for instant energy, starches for slower energy release, and fibres for satiety and enhancement of digestion. A blend of different carbohydrate forms smooths out the energy release mechanisms, which is found in bread but few other foods.
Source of protein, low in fat
Bread is also a good source of dietary protein, required by our bodies for growth, renewal and repair. There are several types of protein in bread made from wheat flour which include albumins, globulins, gliadins, and glutenins. For many, this is a positive source of essential amino acids in the diet. Bread is low in fat and therefore relatively low in calories. An average medium slice of white bread (38g) contains only 0.6g of fat and 77 calories, while wholemeal contains only 0.9g of fat and 79 calories.
Essential micronutrients
As well as the macronutrients, bread contains micronutrients that are essential in our diets. Some of these come from the fortification of white flour that increases selected nutrients to match the levels found in wholemeal flour. The fortified micronutrients in white flour include:
- Calcium - four medium slices per day provide over 30% of the recommended daily intake of calcium needed to maintain healthy bones and teeth
- Iron - important for energy, concentration, a healthy immune system and healthy blood, and
- Vitamins and minerals including those in the B group: thiamine (B1), niacin (B3) and folate (Folic Acid) – all playing a vital role in maintaining good health and well-being.
It is well known that white bread is more popular with consumers than wholemeal. Approximately 89% of breadmaking flour milled in the UK is white, with only 2% brown and 9% wholemeal. White flour consists mostly of the endosperm, which is mainly starch and protein (approximately 80% and 10% respectively). The germ and outer layers of the wheat grain together are called the bran, but most are removed in white flour. These are present in wholemeal flour and make a considerable and positive contribution to fibre in the diet for many people.
Fibre in bread and its contribution to the diet
It is well known that diets high in fibre are associated with a reduced risk of type 2 diabetes, cardiovascular disease and colorectal cancer. Recent Government surveys have shown the UK intake of fibre falls below the recommended amounts. Across all age groups from 1.5 to 75+ years, we consume around two-thirds of the recommended fibre intakes.
Bread, especially wholemeal, is an important source of dietary fibre. As well as disease control, fibre is needed to keep our digestive system healthy, help control blood sugar and cholesterol levels and to make us feel fuller for longer. Wholemeal bread is high in fibre, at 7g per 100g, with white bread providing 2.9g of fibre per 100g. You might find it surprising to know that the fibre levels in white bread are very close to the threshold to qualify as a source of fibre using UK and EU nutrition claim regulatory criteria. These require at least 3g of fibre per 100g or at least 1.5g of fibre per 100 kcal. To put this into perspective, white bread has around 2.9g fibre per 100g.
However, it is not just the quantity of fibre that makes bread such a beneficial product for the diet, but the range of fibre types from wheat. These include arabinoxylans, celluloses, fructans, lignins, β‐glucans and resistant starches (Ref. Bach Knudsen et al). Our digestive system needs a blend of these fibres to work effectively.
The digestion of fibres throughout the gut is a relatively new but complex area of research. It is now known that gut health is more than just digestion. Potentially, the microorganisms that live in the gut, known as the gut microbiota, can affect several aspects of our health and wellbeing, including glucose and lipid homeostasis, energy metabolism, immune function, cancer control and hormone levels. Fibre in bread, particularly wholemeal, could be considered a prebiotic, meaning it feeds our beneficial gut microbes. Better yet, because bread contains a variety of different fibre types, it feeds a range of our good microbes throughout our gut – aiding overall intestinal health.
Cereal fibres, such as those from wheat, possess an almost unique range of fibres among the foods we consume. The rate at which the cereal fibres are digested varies depending on their molecular sizes and structures. Bread digestion starts early on with sugar conversion to glucose, followed by a sequential digestion of starches, fructans and the more complex fibres. Cereal fibres will play a role in most parts of the lower gut, again aiding overall health in many people.
Vitamins
As if feeding the gut microbiota was not enough, there are many bioactive compounds in cereals and bread that benefit our health. Fibre, vitamins, minerals and bioactives are mostly concentrated in the bran (particularly the aleurone component). Bread made from whole wheat contains a variety of bioactive compounds such as phytochemicals. Evidence suggests that diets rich in phytochemicals (present in plant foods) protect against the development of chronic diseases such as cardiovascular disease, type 2 diabetes and cancer. Emerging research suggests that consuming a diverse range of bioactives benefits the gut microbiome, from fruit and vegetables, pulses and whole grains. Bread rich in fibre plays an important role in this.
Wheat, bread and fibre: the key takeaways
Wheat is one of the most important cereals for the UK both commercially and for our health. It is a sustainable crop suited to UK climate and soils with a positive environmental footprint. Wheat flour is a source of macronutrients, micronutrients and a diverse range of fibres of major importance to our health. The diverse fibre types in wheat flour can help maintain a healthy gut microbiome, offering regulation of energy, and protection against disease through an effective immune system. Even bread made from white flour contains many of these nutrients. However, wholemeal flour contains higher levels of fibres and bioactive compounds found close to the outer layers of the grain, making wholemeal bread a beneficial food for many consumers.
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References
- Bach Knudsen, K.E., Nørskov, N.P., Bolvig, A.K., Hedemann, M.S., Lærke, H.N., Mol. Nutr. Food Res. 2017, 61, 1600518. https://doi.org/10.1002/mnfr.201600518
- Nutrition Bulletin, Volume: 45, Issue: 2, Pages: 133-164, First published: 02 June 2020, DOI: (10.1111/nbu.12435)
- The UK Flour Milling Industry (2019). www.nabim.org.uk/uk-flour-milling-industry-2019.pdf
