In the last few years, an increasing number of people have chosen a vegan diet, some for ethical and some for health reasons. This type of diet excludes any products of animal origin, from meat and fish to eggs, dairy products, honey, etc.
Many are the sportsmen, both amateur and professionals, even at a high level, that support this dietary (and for many life) philosophy. Until not many years ago, it was believed that the vegan diet was not compatible with optimal sports performance, above all in those activities that require considerable muscle development. Studies and facts demonstrate that this type of diet is not limiting, but in some cases, you must be more careful than an omnivorous athlete to ensure your body has an adequate supply of some nutrients.
The Academy of Nutrition and Dietetics (AND) too supports the wholesomeness and nutritional suitability of a well-planned vegetarian diet (in all its versions, vegan included). In case of a sportsman, this means that the diet must meet the body’s energy requirements, guaranteeing the quantity of protein necessary for muscles to recover as well as a good amount of vitamins and minerals, of which physical activity demands more. In this context, surely the vegan diet can be as good a solution as the omnivorous ones; in fact, the ingredients of a vegetable diet are very rich in nutrients, among which antioxidant vitamins and minerals that effectively contribute to a quicker recovery from the oxidative damage caused by sports activity as well as support the immune system that often tends to be unsatisfactory in sportsmen of a certain level. This type of diet is characterized by low intake of saturated in favour of mono- and poly-unsaturated fat, and an adequate intake of carbohydrates, the preferred fuel for the body doing activity.
The most serious doubts about the vegan diet hinge on protein intake. The requirement for this nutrient has been evaluated at around 1.2 g/kg of body weight for amateurs and resistance sportsmen, up to 1.7 g/kg for daily and prolonged activities or strength and power sports, reaching 2g/kg in particular cases. According to AND recommendations, these quantities should be increased by about 10% in a vegan because of the high content in fibre of most of these diets. A vegetable diet providing enough calories with an adequate intake of pulses, pseudocereals and dried fruit can meet these requirements, at the same time avoiding increasing the intake of sodium and saturated fat often associated with the consumption of animal protein sources.
In formulating a vegan diet a “shift in paradigm” is required: you must no longer think about the composition of a dish as the association of a source of carbohydrates, one of proteins and another one of fat, but you need to focus your attention on maintaining a balanced and varied diet without looking for isolated protein sources, since vegetables contain all the macronutrients in variable proportions, essential amino acids included. It must be taken into consideration that most vegetables, with the exception of soy and pseudocereals such as quinoa, buckwheat and amaranth, contain a limiting amino acid, that is present in insufficient quantities for optimal protein synthesis; it will anyway be enough to keep a wide variability in the diet to guarantee amino acid complementation, that does not need to take place in the same meal, as it is often stated, because of the presence of a pool of amino acids circulating in the blood and of the protein turnover.
Nutrients and deficiencies
As already stated, a “really” vegan diet, that is based mainly on fresh, whole and minimally processed food, will be rich in vitamins and minerals but there are some nutrients that require attention anyway because at risk of lacking, above all for sportsmen.
The first mineral to take into consideration is calcium. This element is a vital component of the bone structure that stores it and from which it is mobilised in case of need, but it also plays an important role in transmitting the nerve impulse to the muscle and its consequent contraction, as well as in blood coagulation, hormonal secretion, metabolism and DNA transcription. In the vegetable diet too, there are good sources of calcium with good availability (50-60%), such as green-leaf vegetables with a low oxalate content, all types of cabbages, dried fruit and oily seeds, pulses and wholegrain cereal. Another often undervalued source of calcium is mineral water with a low sodium content and a high content of this mineral. The body can partly balance calcium absorption as a response to diets poor in this element or important losses, moreover physical activity can favour its retention. On the other hand, factors that move the balance into the red are a high sodium intake (that in vegan diets is limited and balanced by the high quantities of potassium present in vegetables) and the presence of phytates and oxalates.
Fundamental for the body to work correctly is iron. This mineral takes part in the system transporting oxygen to tissues and in redox reactions, as well as having structural and regulatory functions. The demand for iron increases in athletes, as well as in women because of the loss of blood during their periods. Intestinal iron absorption is controlled by various factors, among which the organic stock (the more iron in the body, the less it is absorbed) and the form it is in. In food, iron is found in two forms: heme iron, that represents 40% of the iron in products of animal origin, that has 25% bioavailability, and non-heme iron, that represents the totality of the iron in vegetables, whose bioavailability can vary from 1 to 25%. The absorption of this mineral from food sources can be promoted by the contemporary presence in a meal of a source of vitamin C or other organic acids, amino acids and sulphurated phytocompounds. On the other hand, the tannins present in coffee, tea, chocolate and red wine, as well as the phytates present in many foods of vegetable origin (wholegrain cereals and pulses), can hamper iron absorption. Sources of (non-heme) iron in the vegan diet are pulses, some vegetables, dried and dehydrated fruit and some aromatic herbs.
Another mineral not to underestimate is surely iodine, indispensable for an efficient metabolism because it contributes to the synthesis of thyroid hormones, as well as to the development of the cerebral and skeletal systems. The recommended daily dose for adults is 150 mcg. Even if present in some vegetables and seaweeds above all, it is difficult to guarantee a sufficient intake from food, so we recommend at least the use of iodised salt, that may not be enough if the sodium intake is controlled.
Zinc is a mineral that plays a part in the functionality of hundreds of enzyme complexes involved in the metabolism, some hormone systems, the cell cycle and immune system (to mention only some of its functions). The recommended daily dose for this mineral is 8-9 mg for women and 11-12 mg for men, without exceeding 40 mg. Even if it is difficult to incur deficiencies and the body can increase absorption in case of reduced intake, a vegan must pay attention to the concurrent intake of food containing zinc with phytates that can reduce its absorption, so that its requirement can be increased by even 50%. As for iron, zinc absorption too is promoted by the concurrent presence of organic acids. In a vegan diet, the sources of this mineral are pulses (chickpeas in particular), wholegrain cereals, yeast, dried fruit (better if sprouted) and oily seeds, as well as some vegetables.
In diets, not just vegan diets, Omega 3 fatty acids are very important. These, together with Omega 6 ones, are essential poly-unsaturated fatty acids, which means that the body cannot synthesise them, so they have to be taken with the diet. Precursor of Omega 3 fatty acids is alpha-linolenic acid (ALA), from which eicosapentaenoic acid (EPA) and docosapentaenoic acid (DHA) derive, while Omega 6 fatty acids derive from linoleic acid (LA), precursor for the synthesis of arachidonic acid (AA). Omega fatty acids play various roles in the body, among them maintaining the cell membranes and modulating the inflammatory response. Omega 3 fatty acids in particular are very important in a sportsman’s diet since they can fight against the inflammation caused by the activity. While the intake of Omega 6 is never really insufficient because of their wide presence in many food sources (attention must be paid not to take too much), Omega 3 fatty acids are more difficult to find in adequate quantities. Even if there is no unambiguous consent, the recommended dose of Omega 3 fatty acids is around 650 mg of EPA + DHA a day. In spite of ALA sources being plenty in a vegetarian diet (linseed, chia, hemps, walnut and soya seeds and oil), it would seem that the conversion efficiency of EPA and DHA is quite poor, even less than 1%. Seaweeds are vegetable sources of EPA and DHA but, in view of their variable and anyway not high content, the intake of isolated Omega 3 fatty acids from microalgal supplements is recommended.
Vitamin B12 is indispensable for the correct function of the nervous and immune systems, the reproduction of red blood cells and energy metabolism. Its deficiency can lead to anaemia and neurological problems. The recommended dose is about 2.4 mcg a day, but higher intake causes no problems, since this is a water-soluble vitamin, whose excess is therefore eliminated with urine. Vitamin B12 has a bacterial origin, in animal products it is possible to find whether animals have been fed with supplemented feeds, while there is none in vegetables, just a minimum quantity on the surface of unwashed fruit and vegetables. The bacteria of the intestinal flora can produce it too, metabolizing food carbohydrates, but not in sufficient quantities. Therefore, it is necessary to take food fortified with this vitamin or target supplementation is even better.
Vitamin D is a fat-soluble pro-hormone that controls numerous genes. Indispensable for the health of the skeletal and immune systems, it ensures also the muscle structure and circulatory system work properly. The conversion of this vitamin in active form (25-hydroxyvitamin D) takes place through the exposure to the sun. The reference blood quota is 50 mg/dl, but deficiencies are frequent because of sedentary and indoor lifestyles. Most active vitamin D in the bloodstream comes from endogenous conversion; as to food sources, in an omnivorous diet, vitamin D is present in small part in food of animal origin, while for vegans intake depends on the consumption of fortified supplements. Apart from more frequent and prolonged exposure to the sun, we recommend supplementation of at least 2000 U.I. a day, possibly to be assessed after blood dosing.
Together with calcium, vitamin K2 plays an important role in the distribution of this mineral in the body and in controlling inflammatory conditions. Unlike vitamin K1, vitamin K2 is not present in foods of vegetable origin if not in few sources like mushrooms, natto, tempeh and supplementation is therefore recommended to reach an amount estimated around 20 mcg a day.
A vegetable diet is surely rich in fibre, very important to regulate the intestinal function and manage the absorption of nutrients in the intestine, however, if this is taken in an excessive quantity in comparison with individual tolerability, it can create problems at gastrointestinal level. In this case we recommend alternating the intake of wholewheat cereals with their refined counterparts and dehusked or puréed pulses.
As it can be deduced from the above, to avoid mineral deficiencies, attention must be paid also in minimizing the concurrent intake of phytates (for instance by soaking pulses for a long time, cooking with the kombu seaweed, etc.), even if these seem to have some beneficial properties to take into consideration, and oxalates.
Dietary needs in peri-training
Let’s now have a look at some advice on the ideal diet to optimize the training of a vegan athlete that, in reality, does not differ from the advice for people following an omnivorous diet, but just requires a bit more attention.
Before training, to prevent problems and not affect performance, it is important to eat food that is not too heavy on the gastrointestinal system. In the hour before training, vegan athletes should therefore pay attention to avoid taking food with a high fibre or fat content, opting for easily digestible carbohydrate sources, perhaps in liquid form. In general, anticipating the meal by an hour in respect of the training every 200 kcal expended is recommended.
Hydration is vital to guarantee correct body temperature and function of the muscle structure during physical activity. During training, the advice is drinking about 180 ml of water every 15 minutes’ activity, to be increased if in very hot rooms and according to sweating. As to the need to replenish nutrients, every sport has its own needs, according to its length and intensity. The range is quite wide, an intake of 30-90 g of carbohydrates per hour of exercise is recommended, always in relation to intensity, not required if the performance lasts less than 60’, except in special cases.
This is perhaps the most important meal, that, if made up well, can favour a quicker recovery. In fact, the body will need water and minerals, to replace the ones lost with breathing and sweating as well as carbohydrates, to restore the stock of glycogen and proteins and repair the muscles. The quantity of carbohydrates required depends very much on the type of activity and therefore on the energy metabolism as well as on duration, and post-training is the best moment to take them, in view of muscle “receptiveness”, while, as to proteins, 25 g in the post-training meal are recommended. As with pre-training, the more absorbable these nutrients are, the quicker the body will be able to use them.
In short, we can certainly say that the vegan choice is perfectly compatible with both amateur and professional sports activity, on condition certain vital things are taken into consideration to ensure the body has all the nutrients it requires, above all those whose need is increased in comparison with sedentary subjects.
Debora Ora, Nutritionist
Responsible for corporesanofitness.com nutrition