A vegetarian or vegan diet is said to be particularly popular among girls and young women. But despite what some people think, these diets, especially vegan diets, are not automatically healthy. A vegan diet can lead to nutritional deficits as a result of the limited choice of foods. These deficits can cause clinically relevant symptoms if they are not balanced out. One of the things to keep in mind is the need for a sufficient amount of vitamins B12 and B6, as well as vitamin D, explains nutritional scientist Bettina Dörr, PhD, from Munich, who specializes in how nutritional science is applied in everyday practice.
Vegetarian and Vegan Diets
According to Dörr, vegetarian diets can be categorized into the following main types:
Ovo-lacto vegetarian (excludes meat and fish)
Ovo vegetarian (excludes meat, fish, and dairy products)
Lacto vegetarian (excludes meat, fish, and eggs)
Vegan (excludes meat, fish, eggs, dairy products, and honey)
Raw vegan (excludes meat, fish, eggs, dairy products, honey, as well as heated food)
The following are additional groups:
Fruitarians want to eat only plant products that do not result in any damage to the plant itself (apples and nuts, for example, but not carrots or potatoes).
Pescatarians exclude meat but still eat fish or seafood.
Dirty vegetarians avoid meat and fish but, according to Dörr, they do not pay particular attention to their diet and eat lots of ready-made and confectionery products.
Flexitarians value a balanced diet and eat meat or fish in moderation, but not particularly often.
Another diet is the orthorexic diet. Followers of this diet force themselves to have a healthy diet and are afraid of getting sick from unhealthy food. As the nutritional scientist explains, orthorexic persons set their own definitions of what is healthy. While some refrain from certain foods (eg, household sugar), others eliminate whole food groups and eat nothing but raw food. Compulsive behavior can appear in specific methods of food preparation or adherence to fixed meal schedules.
The overwhelming majority of orthorexic persons are young women. As shown in a study from the University of Göttingen, orthorexic behavior is displayed above all in active women who play sports, particularly high-performance athletes. Children can also be affected by orthorexia if their parents are.
When following a vegan diet, it is possible to ingest sufficient critical nutrients, even with plant-based foods, according to Dörr. The prerequisite for this is good knowledge regarding food and nutrients. However, it is increasingly the case that foods are “simply left out,” without consideration of the consequences. This factor should be considered when providing medical advice.
Some of the important nutrients in this respect are proteins and vitamins B6, B12, and D.
Girls need 0.9 g/kg/day of protein. For a person whose body weight is 60 kg, this corresponds to 54 g. The daily protein requirement for a person who weighs 60 kg can be fulfilled through a vegan diet. According to Dörr, 54 g of protein is contained in the following:
Vitamin B6 (pyridoxine) has, Dörr explains, multiple metabolic functions, especially in the metabolization of amino acids, and is important from a neurologic perspective. For girls, the vitamin is important for hormone metabolism. Data show that approximately 14% of girls aged 14 to 18 years ingest less than the recommended amount of vitamin B6. For vegans, the percentage of those with insufficient intake is even higher, since vitamin B6 has low bioavailability in plant-based foods. For girls, there is also the additional factor of oral contraceptives. There are indications that those who use oral contraceptives containing estrogen have lower levels of pyridoxal-5’-phosphate (PLP), a marker for vitamin B6. Since the PLP-dependent enzymes are also essential for the synthesis of hormones such as serotonin, symptoms such as depressive moods, increased irritability, nervousness, and loss of libido can also indicate a vitamin B6 deficiency.
The daily B6 requirement for girls is 1.4 mg and can be fulfilled, for example, by consuming the following:
200 g of hazelnuts
200 g of walnuts
400 g of bananas (two to three bananas, depending on weight)
700 g of cooked green beans
1 kg of cooked potatoes
1.4 kg of oats.
Since vitamin B12 is not present in plant-based food, following a vegan diet in the long term can result in deficiency unless dietary supplements are taken. When researching the choices of various dietary supplements, it should be taken into consideration that the utilization of vitamin B12 from plant-based sources such as algae, seaweed, and fungi is not necessarily a given. Careful selection and regular monitoring of B12 status is recommended.
According to Dörr, evidence has increased in recent years that vitamin D is crucial not only for the bones but also for numerous metabolic processes. The fact is that foods are barely capable of covering the vitamin D requirement in amounts that can be expected to be consumed. Vegan foods are not able to contribute to the supply of vitamin D, since considerable amounts are only present in food of an animal origin. The decision to take supplements and in what amounts should be made on the basis of one’s condition.
Calcium, iodine, iron, selenium, and zinc are not easily available in sufficient quantities from a purely plant-based diet. Plant-based foods usually contain lower quantities of these minerals than foods of animal origin, and the minerals from plant-based sources have lower bioavailability. According to Dörr, current evidence suggests that a vegan diet can have negative effects on bone health. In an ongoing cross-sectional study, ultrasound measurements of the heel bone are being made, and biomarkers in the blood and urine are being measured. On average, people who follow a vegan diet have lower ultrasound readings than omnivores.
The European Prospective Investigation into Cancer and Nutrition (EPIC) study from Great Britain, which involved almost 55,000 people, revealed that vegans had a 43% higher risk of fracture, compared to meat eaters.
An important nutrient, especially for cell development, is choline, which, Dörr explains, can be absorbed mainly through eating eggs, fish, meat, and dairy products. There is increasing evidence that a vegan diet is not able to supply sufficient quantities of choline, particularly if requirements increase, such as during pregnancy and breastfeeding. Evidence has grown that women who wish to conceive a child benefit not only from a sufficient intake of folate intake for the prevention of neural tube defects and for favorable fetal development but also from sufficient quantities of choline (the recommended daily amount for pregnant women is 480 mg).