Guest post by Paul Fairbairn, BSc (hons) in Sport and Exercise Science & Nutrition MSc studentThis year the concept of plant-based eating has become very popular. It’s also a concept popular with many Registered Nutritionists and Dietitians, as well as those who care about the welfare of animals and our planet. Plant-based eating comes in many forms, from small dietary tweaks to include more veggies to avoiding meat (vegetarian) and even to eating only plant-based diets (vegan – avoiding all meat, dairy or non-plant based foods).
Choosing to be a vegetarian or vegan has it’s benefits, but it can also be difficult to ensure you receive all the nutrients your body requires and to maintain a balanced diet when removing large food groups such as meat and dairy.
Something that many people don’t recognise is that leading a vegan or vegetarian lifestyle can become even more challenging for an active individual, as physical activity puts more stress on the body and leads to an increase in energy demands. Luckily this is something that can easily be taken care of through proper nutrition and adequate rest. Despite presenting some challenges there are examples of top athletes who are vegetarian or vegan including team GB cyclist Lizzie Armitstead, former tennis star Martina Navratilova, NFL defensive lineman David Carter, strongman Patrik Baboumian and former UFC fighter Mac Danzig.
Here are some of the key dietary considerations for the active person on a plant-based diet:
Removing animal products from the diet, can present an issue in terms of total energy intake as the majority of animal products tend to be highly calorific (fatty meats, cheese, cream etc). In fact when comparing omnivores, vegetarians and vegans, vegans consumed around 600kcal less than omnivores and 350kcal less than vegetarians (Clarys et al., 2014). Total energy intake is vital for athletic performance, without adequate energy intake performance, recovery and adaptations to exercise will suffer. The extent to which this could be an issue depends on your activity level, the more active someone is the more energy they will need to consume. Fortunately this is a very easy issue to address, it’s simply a case of making sure you are eating adequate amounts to fuel your daily activities. This can easily be tracked using apps to measure food intake and by generally being conscious of exercise performance. If physical performance is in decline or unintentional weight loss occurs it could be that daily energy demands are not being met.
Protein is often brought up as a topic when discussing vegetarian and vegan diets, however it is actually very easy to get enough protein despite removing animal products. Protein is important for all active individuals but is particularly essential for strength and power based activities, where demands tend to be higher. There are a number of excellent plant-based protein sources including beans, legumes, nuts and tofu to name a few. We also cannot ignore the protein in vegetables too, they may not have the protein density of meat, but they still contribute to overall protein intake as well as providing vitamins and minerals.
Even though it’s easy to meet total protein requirements in terms of grams per day, we must also consider the quality of the protein sources too. Protein is made up of amino acids, and it is important we get a good range of these amino acids. Even if someone consumes a large quantity of protein, if they are missing out on some of those amino acids, they will not be able to perform optimally, both from a health or performance perspective. There are a number of plant-based foods with diverse amino acid profiles for example quinoa, hemp and soy, however these foods often have what is referred to as a limiting amino acid. This means that even though a food contains a good range of amino acids a certain amino acid may only be present in a very small amount, that wouldn’t be enough to meet requirements. Again this can easily be addressed by eating a range of protein sources throughout the day. A good example of this is that the proteins found in wheat and haricot beans complement each other well and together make a complete protein, making beans on toast a suitable plant-based protein meal.
Iron and Vitamin B12
It’s actually not uncommon for vegetarians and vegans to have greater intakes of iron compared to omnivores. There are a number of plant-based sources of iron including dark green leafy veg, legumes and nuts. However these foods contain a form of iron called non-haem iron, which is not absorbed as well as the haem iron that is found in meat sources. Therefore it is particularly important for vegetarian and vegan athletes to make sure they are consuming adequate amounts of iron rich foods to meet their requirements. Based on the lower absorption of plant-based iron, one study has highlighted a recommendation that vegetarians should increase their iron intake by 80% to meet demands (Hunt, 2003). This can be achieved through a varied diet containing 8 servings of grains, 3 of vegetables, 2.5 of green leafy vegetables, 1.5 of fruit, 1.5 of dried fruit, 2.5 of beans and protein foods, 3 of dairy or fortified non-dairy, 1.5 of nuts and seeds, and 2.5 of oils (Hunt, 2003). Iron absorption can also be aided by avoiding coffee and tea around meal times as the tannins in these drinks lower absorption. Iron intake is of particular concern for female athletes, due to loss through menstruation. Furthermore iron is especially important for those taking part in endurance activities, as these activities require greater intakes to maintain performance (Hinton, 2014). Dark green leafy veg is particularly good for active individuals as these also are a source of calcium and magnesium, which are essential for normal muscle function.
Low vitamin B12 intakes can result in anaemia and nervous system damage. These conditions are associated with reduced oxygen transport resulting in reduced performance, especially in endurance or more aerobic activities. B12 is produced by bacteria in the gut, and is only naturally contained in animal-based foods. It is almost impossible to get enough on a purely plant-based diet, unless consuming foods that are fortified, however vegetarians can get some by consuming eggs. It is generally accepted that vegans should supplement with vitamin B12. 6µg per day is commonly recommended (Fuhrman & Ferreri, 2010).
Omega 3 Fatty Acids
There is some evidence to suggest that consumption of the essential fatty acid – omega 3, may reduce inflammation associated with physical activity (Bloomer et al., 2009). Plant-based sources of omega 3 fat include flaxseed, chia seeds, walnuts and hemp seed, which principally contain the omega 3 fatty acid alpha linolenic acid (ALA). The active forms of the omega 3 fatty acids in the body are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which can be converted from the plant source ALA. Unfortunately the body’s ability to perform this conversion is extremely limited. Conversion of ALA to EPA and DHA has been estimated to be 5% and 0.5% respectively (Plourde & Cunnane, 2007). Again this extenuates the need for those consuming a purely plant-based diet, to make sure they are consuming adequate amounts of omega 3 fats. There are supplements derived from algae that are suitable for vegans that contain omega 3 preformed as EPA and DHA, which could be considered.
To conclude there are a number of considerations that need to be made when switching to a vegetarian or vegan diet, particularly if you are physically active. However if the right steps are taken there is no reason why a physically active person cannot flourish and perform well, whilst removing animal products from the diet.
Bloomer, R., Larson, D., Fisher-Wellman, K., Galpin, A. and Schilling, B. (2009). Effect of eicosapentaenoic and docosahexaenoic acid on resting and exercise-induced inflammatory and oxidative stress biomarkers: a randomized, placebo controlled, cross-over study. Lipids Health Dis, 8(1), p.36.
Clarys, P., Deliens, T., Huybrechts, I., Deriemaeker, P., Vanaelst, B., De Keyzer, W., Hebbelinck, M. and Mullie, P. (2014). Comparison of Nutritional Quality of the Vegan, Vegetarian, Semi-Vegetarian, Pesco-Vegetarian and Omnivorous Diet. Nutrients, 6(3), pp.1318-1332.
Fuhrman, J. and Ferreri, D. (2010). Fueling the Vegetarian (Vegan) Athlete. Current Sports Medicine Reports, 9(4), pp.233-241.
Hinton, P. (2014). Iron and the endurance athlete 1. Appl. Physiol. Nutr. Metab., 39(9), pp.1012-1018.
Hunt, J. (2003). Bioavailability of iron, zinc, and other trace minerals from vegetarian diets. American Journal of Clinical Nutrition, 78(3), pp.633-639
Plourde, M. and Cunnane, S. (2007). Extremely limited synthesis of long chain polyunsaturates in adults: implications for their dietary essentiality and use as supplements. Appl. Physiol. Nutr. Metab., 32(4), pp.619-634.