According to the 2016 U.S. Academy of Nutrition and Dietetics’ position on vegetarian diets (1), the vegetarian and the vegan diets are suitable at all stages of life, including childhood, adolescence, pregnancy, lactation and senescence. It is also suitable for athletes.
SORRY, THAT IS NOT CORRECT
It is true that adolescence is a period of growth and development that demands greater energy consumption. However, it is not true that a vegetarian or vegan diet is insufficient to meet that demand. Regardless of the type of diet they follow, adolescents often have a physiological increase in appetite. In this sense, the only precaution that must be taken is that the energy supply is sufficient. This increase in demand is usually solved by adding a snack between breakfast and lunch and another between lunch and dinner.
Here are some healthy snack ideas for kids and teens who follow a vegetarian or vegan diet.
VIDEO WITH HEALTHY SNACKS.
In fact, all macros and micronutrients can be substituted except one: vitamin B12, because it is the only one that is only found in animal products. Until recently, it was thought that ovolactovegetarian people ingested the necessary amounts of vitamin B12 thanks to eggs and dairy products and derivatives. However, with the 2015 recommendations of the European Food Safety Authority (2), the number of eggs, dairy products and derivatives that should be consumed are unviable. For this reason, dietary supplementation with vitamin B12 is essential for vegans and highly recommended for vegetarians.
Vegetarians and vegans have been observed to have lower serum iron levels, but this does not translate into a higher prevalence of anemia. That is, these lower levels of serum iron do not have any clinical consequences and, therefore, supplementation is not necessary (3).
The best-known sources of iron are meat and seafood, however, vegans/vegetarians can intake iron from the consumption of legumes, nuts, seeds, whole grains, and dried fruits. Because of its chemical structure, the iron present in plants is absorbed less than the iron present in meat. In addition, the phytates present in whole grains, legumes and seeds may interfere with iron absorption. However, given its adaptive capacity, the body of people who follow a vegan /vegetarian diet undergoes modifications that favor absorption and reduce iron excretion.
Some products suitable for vegans/vegetarians are fortified in iron, but in addition, there are strategies that favor the absorption of iron in a vegan/vegetarian diet (4):
Milk and dairy products are a good source of calcium, but calcium can be found in many plant-based products so it cannot be concluded that milk and dairy products are essential for a balanced diet.
Almonds, beans, tofu and cruciferous vegetables (cabbage, collard greens, cauliflower and broccoli), watercress and arugula are sources of calcium. Calcium in tofu has an absorption of 30%, similar to that in milk. Green leafy vegetables, such as chard and spinach, are rich in calcium, but they are also rich in oxalates, which bind to calcium in the gut and prevent its absorption.
Vegan/vegetarian diets have not been seen to be associated with lower bone density or an increased risk of fractures as long as the intake of calcium and vitamin D is adequate (5). Although the availability of plant calcium is not as high as that of dairy products, intestinal absorption is dependent on nutritional status, and may increase when necessary to maintain adequate levels.
An increased risk of bone fractures has been observed in vegans with insufficient calcium intake. In those cases, it is advisable to correct the dietary intake of calcium, ensure an adequate supply of vitamin D, responsibly expose to sunlight and exercise.
Vitamin B12 is only found in animal products. That’s why vegetarians and vegans need supplements of this vitamin. Until recently, it was thought that ovolactovegetarian people ingested the necessary amounts of vitamin B12 thanks to eggs and dairy products and derivatives. However, with the 2015 recommendations of the European Food Safety Authority (2), the number of eggs, dairy products and derivatives to be consumed is unviable. For this reason, dietary supplementation with vitamin B12 is essential for vegans and highly recommended for vegetarians.
ACTUALLY, THIS IS DOUBTFUL
This is a controversial issue. The omega-3 fatty acids EPA and DHA are considered essential fatty acids because our body cannot generate them and therefore must be ingested through the food. EPA and DHA are found in fish, some microalgae, and meat from grass-fed animals. However, our body can obtain, although in very small amounts, EPA and DHA from alpha-linolenic acid present in nuts, soybeans, and flax seeds.
It has been seen that serum level of DHA in vegetarians is similar to that of people who do not consume fish, so, if the conclusion was that vegans or vegetarians need supplementation, the same recommendation should be extended to the entire population that does not consumes fish regularly.
However, it is important to note that vegan diets are usually poor in omega-3 fatty acids and rich in omega-6 fatty acids, present in nuts and cereals, which have a pro-inflammatory effect. The omega-6:omega-3 ratio in diet is very important. Since the recommended ratio is 2:1 or 4:1, omega-3 supplementation may be necessary in some vegan diets.
In an omnivorous diet, animal products that are excluded from a vegetarian or vegan diet are, above all, the main source of protein. It is not uncommon for a person without knowledge in nutrition and dietetics who wants to start a vegan diet to replace animal products with carbohydrate-rich products (pasta, rice, potato and bread) or ultraprocessed vegan products which provide no o very few proteins. That is way some people believe vegetarian/vegan diets do not provide the required amount of protein. However, that idea is based on dietary ignorance, since there are plant foods that guarantee a sufficient supply of protein and can substitute animal products, which are the main source of protein in omnivorous diets.