Crusts? Why cutting off your crusts wastes a great nutritional resource
By Laurentia Campbell, biomedical scientist, neuroscientist and nutritionist writer.
Many parents know the battles that surround trying to get kids to eat their crusts, with a few continuing this habit into adulthood, leaving their bread crusts behind. Over 11.5 billion sandwiches are consumed worldwide and a staggering 20,000,000 slices of bread are wasted each year in the UK alone according to research by WRAP, contributing to 1/3 of global carbon emissions (66% of which occurs at home). Scientific evidence suggests that there are many health benefits in the crusts, with the crusts containing the anti-ageing, anti-inflammatory and anti-cancer compound pronyl-lysine. It's time we all ate our crusts for our health and stopped wasting this amazing nutritional resource.
What are the health benefits of eating bread?
The health benefits in the crust depend on the type of bread consumed and the grain type and level of processing in the flour. The best bread is wholegrain, with as few ingredients as possible. This is because when bread is refined to make white bread, and the outer aleurone layer and bran are removed, many vitamins and minerals such as energy-giving magnesium, B vitamins and iron are removed. Fibre is also most concentrated in the bran and we need fibre for our gut health and gut microbiota. It is also the most filling part of the bread and helps to move food through the digestive system, so helps reduce constipation. Fibre also slows the release of sugars from our food into the blood, so we have more long-lasting energy. Removing these layers removes these benefits and leaves the ultra-processed white wheat flour behind. This ultra-processed refined white flour contains carbohydrates which are easily absorbed into our bloodstream and cause quick spikes in our blood sugar. These give us quick-acting, short-lasting energy compared to wholegrain complex carbohydrates which give us more slow-acting, long-lasting energy.
Some grain types are better than others for health too, with Flax grains, spelt, Amaranth, Buckwheat, Millet, Quinoa, Soy and Tapioca being gluten-free and so lower glycemic index and less likely to cause our blood sugar to rise and get blood sugar spikes and troughs that make us hungry and tired. Rice flour is gluten-free but white rice is like white flour and is refined and the wholegrain outer layers are removed. The best rice flour is wholegrain or wild or brown rice flour. Almond and peanut flour is also high in protein and low glycemic index (it causes our blood sugar to rise the least) so keeps you fuller for longer.
The amount of preservatives added to the grain also impacts its health benefits, with the best bread containing simply yeast, flour and salt (or ghee or oil or herbs or cheese or sourdough starter if sourdough or buttermilk if soda bread, depending on the bread type). Those with ultra-processed artificial ingredients and trans fats, such as vegetable oils and fat (Rapeseed oil, Palm fat, Palm oil), Spirit vinegar, preservative (Calcium Propionate), emulsifiers (Mono- and Diacetyl Tartaric Acid Esters of Mono- and Diglycerides of Fatty Acids, Mono- and Diglycerides of Fatty Acids), are the least healthy. Adding protein in the form of seeds and nuts to the bread or milk, soya or cheese, also increases the benefits of the bread as protein is the most filling macronutrient and helps to build muscle, skin and hair and control metabolic (energy-making and transferring) reactions in the body. The more energy we have the better we feel mentally and physically.
What about the benefits of the crusts? How can they help stop ageing, cancer, IBS and improve our gut microbiota?
A study by German scientists Lindenmeier, Faist and Hofmann (1) in the Journal of Agricultural Food Chemistry 2004, found that the crusts of bread (produced in a browning Maillard reaction when the bread is cooked) have antioxidative benefits. The crusts were found to contain pronyl-lysine, which helps to fight pro-inflammatory, cancer-causing compounds (carcinogens) called reactive oxidative species (ROS), and therefore helps to defend against disease. This antioxidant was found to neutralise oxidative species and prevent inflammation, and DNA, skin and blood vessel damage that occurs in our bodies. Oxidative species can be caused by everything from UV DNA damage, ageing, and excess sugar (which causes advanced glycation endproducts which create oxidative species). Therefore the crusts with the increased antioxidant capacity, can help defend against ageing, cancer from DNA damage and inflammatory diseases such as Inflammatory Bowel Disease (IBS) and arthritis.
However, it should be noted that this key antioxidant and all health benefits in the crust and bread itself are destroyed if the bread is overcooked, or burnt, and burnt bread is itself carcinogenic. For health, you should never consume burnt bread.
Most of the prebiotic (feeds your healthy gut microbiota and helps them grow) resistant fibre is concentrated in the ends of the bread too. Therefore the crusts have the most benefit for digestive health and have the most gut microbiota-boosting capacity. The gut microbiota has benefits for everything from our brain health (via the gut-brain axis), to our ability to fight disease (as they regulate our immune system) and our ability to regulate inflammation (as they impact an immune cell called Treg which helps control inflammation). The gut microbiota, as shown by the scientist Power and team (2), also helps control our response to sugars, fats and carbohydrates, and the amount of energy we get from our food. Therefore prebiotic fibre sources like bread crusts of wholegrain bread or non-starchy vegetables, have huge potential benefits.
Overall? Get crusty!
For the sake of your health and the planet's health, you should eat your bread crusts and encourage your kids to as well. They are likely to carry into adulthood whatever habits they learn in childhood. To make the crusts more appetising, you can heat them up slightly in the microwave or oven, or make sure you add butter and jam or mayo from the sandwich, right to the bread edges. Time to get crusty!
Copyright Laura Campbell 14/03/2024
References
- Lindenmeier M, Faist V, Hofmann T. Structural and functional characterization of pronyl-lysine, a novel protein modification in bread crust melanoidins showing in vitro antioxidative and phase I/II enzyme modulating activity. J Agric Food Chem. 2002;50(24):6997–7006.
- Power SE, O’Toole PW, Stanton C, Ross RP, Fitzgerald GF. Intestinal microbiota, diet and health. Br J Nutr. 2014;111(3):387–402.
