Vegan diets have become noticeably more popular in recent years. Many people will choose to exclude all animal products from their diet for ethical reasons. Others may see it as a healthier way of eating. Or it may well be a combination of the two. I’ve certainly observed an increase in the number of endurance athletes who are turning to veganism. That’s great if it’s the right decision for you, and it is certainly possible to be both vegan and a high performer, but you do need to be aware of several potential risks to both your health and your performance if you follow a vegan diet which isn’t well balanced and doesn’t take account of potential nutrient deficiencies.
A paper in the Journal of the International Society of Sports Nutrition in September 2017 1 has taken an in-depth look at this topic. In this blog post, I will summarise the issues and recommendations from that paper that are relevant to endurance athletes following a vegan diet. It is important to note that very little research has been done specifically on vegan athletes and their health and performance, so these recommendations are mainly drawn from research on non-athletic populations. But they are still well worth paying attention to, and hopefully more specific research on vegan athletes will be published in future years.
Here’s what you need to know so that you can put together a vegan diet that supports both your endurance sports performance and your health.
1. Energy Intake
The issue: a plant based diet is by its nature high in fibre. This can have many benefits for health but it can also satiate your appetite before you have taken on board enough calories to satisfy your energy requirements. This can be a significant issue for vegan endurance athletes, particularly on heavy training days or during training camps. If not managed carefully, you may be at risk of Relative Energy Deficiency Syndrome (RED-S) which has potentially negative effects on many aspects of health and performance. See my blog post here.
The solution: include plenty of healthy fats in your diet, such as avocado, nuts and seeds, to boost your calorie intake (fat has 9 calories per gram compared with 4 calories per gram for carbohydrate and protein). Eat frequently – try 4-5 mini-meals daily. Match your energy intake to your energy expenditure by planning ahead and consciously eating greater quantities and choosing lower fibre foods on demanding training days, eg white rice, pasta, noodles. Be aware, as well, that high fibre food such as oats, wholegrain bread, beans and lentils may be best avoided in the 24-48 hours before races to help prevent stomach issues on the day.
2. Protein Intake
The issue: there’s general agreement among sports nutrition researchers that athletes have greater protein requirements than the general population, and other research shows that vegans often have lower protein intakes than omnivores or vegetarians who consume eggs and dairy products. While many plant foods provide a source of protein, few provide all the essential amino acids (EAAs) which your body is unable to make itself. Plant protein also has a lower biological value than animal protein, ie less of it gets absorbed by your body, meaning that you need to eat more of it to get the same amount of protein.
The solution: Eat a range of different plant food groups, eg grains, legumes and nuts & seeds, each day to ensure you have all the necessary amino acids. Regularly consume the few plant proteins with a full complement of EAAs, eg soya, quinoa, buckwheat and chia seeds, although be aware that the EAAs in these foods may not be in the ideal proportions, so having a variety is important. Aim for the higher end of protein recommendations for athletes (1.4g-2.0 g/kg of body weight) to help compensate for reduced absorption of plant proteins. Use vegan protein powders to help you reach this, particularly after training. Choose a soya-based product or one that combines rice and pea protein.
3. Fat Intake
The issue: research suggests that vegan diets are typically lower in total fat and especially saturated fat than diets containing animal fats. While this may have benefits for heart health – although this is increasingly being questioned in the light of more recent research – a lack of omega 3 fatty acids may put vegans at risk of immune or hormonal dysfunction which may in turn impact on performance. The primary source of the omega 3 fatty acids EPA and DHA is oily fish. While certain nuts and seeds do contain alpha linolenic acid (ALA) which converts to EPA, the conversion rate is very low (around 8%) and there is no conversion to DHA. A low-fat diet may also increase risk of energy deficiency, as already discussed.
The solution: ensure that you have sources of ALA in your diet such as walnuts, flax seeds, pumpkin seeds and chia seeds. Be careful not to overconsume seed oils which are high in omega 6 oils, eg sunflower oil, which may be pro-inflammatory when there is inadequate omega 3 in the diet. Cook with olive oil and coconut oil instead, and use these in place of vegan spreads on bread. Take an omega 3 supplement derived from algae to provide additional EPA and some DHA. Here’s a suitable supplement which is available in the UK: https://www.cytoplan.co.uk/omega-3-vegan. Boost your fat intake by including avocado, nuts, seeds, coconut and olive oil in your daily diet. Ensure you have a variety of these different fats each day.
4. Vitamin B12
The issue: vitamin B12 is arguably the micronutrient that vegans are most likely to become deficient in. This is because vitamin B12 is not found naturally in plant foods. Vitamin B12 is essential for normal functioning of the nervous system and for DNA synthesis. It’s also needed to produce healthy red blood cells. One of the signs of B12 deficiency is fatigue. If you are a vegan athlete and notice an unusual level of fatigue, please visit your doctor for a blood test to rule out B12 deficiency or receive treatment for identified deficiency, such as an intravenous B12 infusion.
The solution: include some foods that are fortified with B12 in your diet, such as certain brands of cereal or plant milks. Yeast extract or nutritional yeast flakes are other vegan-friendly sources. I would also recommend that you supplement vitamin B12, either as a standalone product or as part of a high quality multi-vitamin. Sub-lingual lozenges or sprays may be better absorbed than tablets, but evidence is lacking for this.
The issue: this is less about the amount of the iron consumed by vegans, which has been found to be similar to the intake of omnivores, as iron is found in many plant foods, and more about the absorption of that iron. Plant sources of iron are found in the non-haem form which is less well absorbed than the haem form found in animal foods. Iron is essential for energy production so having adequate levels in the blood is very important for athletic performance. See my blog on iron for more information on the role of iron, signs of inadequate iron and how to have your iron levels monitored if you suspect iron deficiency. Fatigue is just one symptom.
The solution: non-haem iron is better absorbed if you consume it alongside a source of vitamin C, found in many fruits and vegetables. It’s also best to avoid drinking coffee or tea at the same time as eating your meal, as the tannins in those drinks inhibit iron absorption. Whole grains and legumes are useful sources of iron for vegans, but also contain substances called phytates which reduce absorption. Due to these absorption issues, vegans should aim for a higher intake of iron from food than omnivores. This is particularly important for menstruating women, who lose iron during their monthly bleeds. As well as wholegrains and legumes, other vegan sources of iron include nuts, seeds, leafy green vegetables, tofu and fortified foods such as certain breakfast cereals. Legumes should be soaked or sprouted to reduce phytates. Cooking in iron-based pans may also be helpful. Taking iron supplements, beyond the amount found in multivitamin products, is not recommended without the advice of a qualified health professional and a confirmed deficiency, as too much iron may have adverse health consequences.
The issue: zinc is critical for cell growth and repair and for protein metabolism. Like iron, zinc is found in many plant foods but it is not readily absorbed, partly due to the presence of phytates in many of those foods.
The solution: include plenty of wholegrains, nuts, seeds and legumes in your diet to provide zinc. Soaking helps to reduce phytates. Choose fermented breads such as sourdough rye. Aim to consume more than the daily recommended amount of zinc to compensate for reduced absorption, and consider taking a standalone supplement if this is difficult. As supplemental zinc absorption may be compromised when it is in competition with supplemental iron, calcium, copper, magnesium and folic acid, take this at a different time from any multi-vitamin/mineral product you may be taking. It is not thought that this competition applies in the same way to micronutrients found in wholefoods.
The issue: calcium is needed for physiological functions beyond bone health, such as nervous system and muscle function. As they do not consume dairy products, vegans are generally found to consume less calcium than omnivores and vegetarians. They have also been shown to be at higher risk of fractures due to low calcium intakes leading to reduced bone mineral density. While legumes, nuts and certain green vegetables are sources of calcium, they contain phytates and oxylates respectively, which are known to impede absorption.
The solution: legumes and nuts should be soaked if possible. Low-oxylate green vegetables include broccoli, kale and bok choi, whereas spinach and rocket (arugula) are high in oxylates. Ensure that any plant milks you drink are fortified with calcium. If you experience a stress fracture, have your blood calcium level measured and ask for a DEXA scan to assess bone mineral density. You may need to take a calcium supplement, particularly if you struggle to meet your energy requirements through sufficient food intake. Read more about calcium for endurance athletes in my blog here.
The issue: the trace mineral iodine is essential for growth and development, as well as thyroid function and metabolism. Vegans have been shown to consume low intakes which may result in deficiency. Fish and dairy products are both sources of iodine, which obviously do not feature in a vegan diet. The main vegan source is seaweed and some vegans have been shown to consume amounts resulting in an excess of iodine which may adversely affect normal thyroid function.
The solution: do include some seaweed in your diet, but perhaps not every day. Good choices are nori, wakame and kombu. Sprinkle on salads or eat in vegan sushi rolls. Iodized table salt is another option. Not directly related to iodine, but a point to be aware of is that eating substantial amounts of raw cruciferous vegetables such as broccoli, cabbage and cauliflower may adversely affect thyroid function due to substances called goitrogens. However, these are largely destroyed by cooking. Do steam your cauliflower or broccoli ‘rice’ before eating. If you cannot consume sufficient iodine in your diet, consider a supplement giving you 150 mcg daily.
9. Vitamin D
The issue: vitamin D is now known to contribute to many functions of the body beyond bone health, where it is needed for optimal calcium absorption. These include muscle function and the immune system. Having optimal vitamin D status is now regarded as an important part of sports performance as well as general health. To read more about the latest research behind this, see my blog here. As there is little vitamin D in foods generally, and virtually none in plant foods (mushrooms specially grown in sunlight may be an exception), we get most of our requirements from the action of sun on skin, which converts steroid hormone precursors to active vitamin D. However, at northern latitudes, including the UK, the sun is not strong enough during the winter months for this process to take place and supplementation is now advised for many population groups, including athletes. The issue for vegans is that the plant derived form of vitamin D, ergocalciferol, also known as vitamin D2, is less available to the body than animal derived vitamin D3 or cholecalciferol.
The solution: have your vitamin D status tested, which can be done by your doctor or relatively cheaply via a home-based pin prick blood test. If your levels are less than optimal, usually regarded as somewhere between 75-100 nmol/L, consider using a vitamin D3 supplement that is derived from lichen (a vegan-friendly fungal-algae organism) rather than vitamin D2. Here’s an example from the Nordic Naturals brand: http://www.nordicnaturals.com/en/Products/Product_Details/514/?ProdID=1673
10. Creatine and Beta Alanine
The issue: these are two well researched supplements that I do not usually use with endurance athletes as their benefits are linked to high intensity exercise and intermittent sprints, eg in team sports. However, vegans have been found to have lower levels in muscle of both creatine and carnosine (for which the precursor is beta alanine) than omnivores as the main dietary sources are meat, poultry and fish.
The solution: if your endurance sport includes an element of sprinting or sustained high intensity, eg criterium bike racing, 10mile or 25mile cycling time trials, sprint triathlon or 3000m/5000m run races, as a vegan you may benefit from supplementing synthetic creatine and/or beta alanine. Watch out for gelatine capsules and see the paper I have referenced below for details on how best to take these supplements.
I hope that this extensive blog post gives you some idea of how you can be both vegan and a high performing endurance athlete. At the same time, I hope it has also made you more aware of how important it is that you eat enough food to meet your energy needs and do not fall short of the nutrients which may potentially be low in a diet that excludes all animal products, including protein, fat, vitamin B12, iron, zinc, calcium, iodine and vitamin D. To do so risks compromising both your health and your performance. Pay as much attention to your nutrition as you do to your training, and there’s no reason why you shouldn’t achieve the performance outcomes that you are looking for. Finally, look at the sample 2500 and 3500 calorie sample menus in the paper referenced below to see some great examples of how to put together an appropriate daily vegan diet for an athlete.
Jo Scott-Dalgleish BSc (Hons) is a BANT Registered Nutritionist, writing and giving talks about nutrition for endurance sport. Based in London, she also works as a Registered Nutritional Therapist, conducting one–to–one consultations with triathletes, distance runners and cyclists to help them eat well, be healthy and perform better through the creation of an individual nutritional plan. To learn more about these consultations, please visit www.nutritionforendurancesports.co.uk
1 Rogerson D. Vegan Diets: practical advice for athletes and exercisers. J Int Soc Sports Nutr. 2017. 14:36. https://jissn.biomedcentral.com/articles/10.1186/s12970-017-0192-9
This paper contains a wide range of references, including various research studies alluded to in this blog. It is freely available at the above link as a download or PDF.