Is plant-based fuel the recipe for success for athletes?

Of course, the energy athletes need depends on their body, performance goals and training regime, which means that energy intake differs between sports. However, more athletes are extolling the virtues of plant-based eating, and researchers want to know whether they perform better because of their vegan diets, but this is hard to prove.

A number of studies suggest that plant-based diets can help people lose weight and become leaner while improving stamina, but most of their findings have been in average people – not professional athletes. Andrew Shepherd, performance nutrition lead at Loughborough University, says: “At this stage there isn’t a strong evidence base for a vegan diet being healthier than an omnivorous diet.”

However, as more athletes successfully swap meat for plants, the field of research is widening, and more benefits of veganism are being tested. For example, it’s possible that a plant-based diet might give athletes an edge because it tends to be high in complex carbohydrates. These carbs are found in whole grains and are particularly important for endurance training, and help athletes maintain a consistent supply of energy throughout the day.

“A high-carbohydrate diet remains the evidence-based recommendation for athletes who engage in hours of physical activity on a daily basis,” according to an article published in the journal Nutrition Reviews. Another study suggests a plant-based diet can help athletes recover after hard workouts by increasing blood flow and tissue oxygenation and reducing oxidative stress and inflammation.

With careful management, a varied diet of fruits, vegetables, grains and legumes, along with a vitamin B12 supplement, provides all of the necessary nutrients an endurance athlete needs, including protein, calcium and iron, and might come with a feel-good extra. “The trend we see, with anyone from athlete to general population, is that when people switch to vegan diets their fruit, vegetable and salad intake rises and therefore they consume more fibre as well as certain vitamins and minerals compared to their previous diet, which can help feelings of wellbeing in the short term,” says Shepherd.

Dr Javier Gonzalez, reader in human metabolism at the University of Bath, agrees that anyone who swaps to a vegan diet tends to see benefits from eating more vegetables. “Plant-based foods tend to be lower in energy density, so people tend to consume fewer calories,” he explains. “Weight loss can be a goal for some athletes.”

On the flip side, vegan diets can make it difficult to get sufficient calories for athletes who undertake lots of training and want to maintain or put on weight. “For athletes with very high energy demands and who require a high calorie intake, consuming enough can be a challenge,” Shepherd says. “No sport lends itself more positively to vegan athletes, but endurance or ultra-endurance athletes can often see more challenges when adopting this diet.”

Multiple studies show that vegans may end up consuming less protein and fat than omnivores without careful planning, and struggle to get enough vitamins and minerals such as B12. “Typically, on a gram for gram basis, animal-based protein is more potent at stimulating muscle growth,” says Gonzalez. This can be managed by increasing the amount of vegan protein consumed, such as soy, but simply eating a lot of one plant-based protein isn’t the answer, as vegan protein sources do not tend to contain all essential amino acids, which are the building blocks of protein. This means variety is essential and vegan athletes must eat foods with complementary amino acid profiles to meet their muscle-building needs.

“The rule of thumb is that you combine a grain with a legume. They complement each other because the amino acids that rice is lacking in can be made up for with peas,” Gonzalez explains. “If people following a vegan diet can combine different sources of protein, they can then achieve the same result as people eating animal-based proteins.”

Luckily, there are some classic combinations that make this simpler. “Corn and kidney beans are the Mexican version [of an ideal vegan meal] and the Caribbean version is the rice and peas,” Gonzalez says.

Unbalanced plant-based meals can be deficient in certain important nutrients, including iron, omega three and more. “Nutrients are important for general health, but especially for athletes. Take iron, for example; it’s really important for the production of red blood cells,” Gonzalez explains. Haemoglobin is a protein in red blood cells that carries oxygen from our lungs to all parts of the body, while myoglobin – another protein made by iron – brings oxygen to our muscles. More red blood cells make these processes more effective, resulting in better athletic performance, so getting enough iron to make the red blood cells in the bone marrow is vital.

Mindful vegans can obtain enough iron from beans, lentils, nuts, tofu (bean curd) and dark leafy veg, and because their diet is often high in vitamin C, absorption of this important element is improved. But sometimes supplements are needed. “For example, vegan foods do not naturally contain vitamin B12, and it would be recommended to take a supplement,” says Gonzalez.

Creatine – a chemical found naturally in the body that’s also in red meat and seafood – is a popular supplement for athletes, especially sprinters and weightlifters who need a burst of energy and explosive power. It is often used to improve exercise performance and muscle mass, because creatine is involved in making energy for muscles. “If you just measure the amount of creatine in the muscle of people who eat meat versus people who don’t, then it will be slightly higher,” Gonzalez explains. “But if you really want to get the performance benefits from creatine, you probably do need to supplement, because the amount you can get from a supplement is so much higher than you can get from meat.”

Just as a growing number of us have got a taste of going vegan – with Sainsbury’s predicting in 2019 that a quarter of the UK will be vegan or vegetarian in 2025 – it seems probable that we’ll see more plant-powered athletes winning medals too. But many vegan ‘wins’ such as better endurance should perhaps be taken with a pinch of salt (or should that be B12 yeast flakes) as this area of research is also still emerging and anecdotal evidence is being put through its scientific paces.

Simply put, chowing down on a chicken caesar salad may be a quicker and easier way of meeting protein needs than balancing plant-based proteins, but for some athletes, it’s worth the effort – and having a nutritionist or chef on hand probably makes it easier!