Today, vegetarian diets are considered more than anything else as a "set" of eating styles.
In this article, however, we will talk only and exclusively about the possible shortcomings related to some specific forms of vegetarianism:
- Lacto-ovo vegetarian diet (or only ovo-, or only lacto-): excludes meat and fish products, but includes milk and derivatives, and / or eggs;
- Vegan diet: excludes any food of animal origin, therefore also milk and derivatives, eggs, honey etc. It can include microorganisms such as fungi and bacteria.
What possible deficiencies can manifest themselves in vegetarian diets?
Below we will only talk about "possible" deficiencies, as there are various discretionary factors that can make the difference on the nutritional balance of a vegetarian diet; for example: care in the choice of food sources, level of physical activity, any special physiological conditions (pregnancy, breastfeeding) or pathological, use or not of supplements, life phase (growth, old age) etc.
It is therefore first of all necessary to understand what are the nutritional functions attributable to the various food groups.
For further information: Vegetarian Diet: What it is and How It Works etc.) offal, fresh and salt water fish, other fishery products (crustaceans and molluscs) and all eggs.
They mainly provide proteins with a high biological value (VB), highly bioavailable iron (heme and divalent or Fe2 +), numerous water-soluble vitamins of group B (thiamin or vitamin B1, riboflavin or vitamin B2, niacin or vitamin PP and cobalamin or vitamin . B12).
How not to mention the other 3 great nutritional qualities of sea fishing products, namely the "abundance of:
- vitamin D3 (calciferol: 1,25- (OH) 2-cholecalciferol);
- iodine;
- biologically active essential fatty acids (EFA) of the omega 3 group, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
The other food rich in calciferol and polyunsaturated fatty acids, part of which is essential, is egg yolk.
Offal, such as the liver, kidneys, heart and spleen, are real reservoirs of valuable minerals and vitamins.
Attention! On the flip side, some of these products also provide significant amounts of cholesterol and saturated fats, which if introduced in excess are anything but healthy (especially in the presence of metabolic diseases). To the abuse of processed meats - because they contain nitrates and nitrites - and of all the other cooked ones, overcoming the thermal stability of fats and proteins, an increased risk of carcinogenesis of the stomach and intestine is correlated.
In this sense, vegetarian diets play a protective role.
II ° fundamental group of foods: milk and derivatives
It includes all types of milk - even condensed and powdered milk - and all processing derivatives.
They too provide high VB proteins but, unlike the previous one, they contain less iron but a lot of bioavailable calcium and phosphorus.
Attention! Again for "par condicio", we must report that even non-skimmed milk derivatives bring significant quantities of cholesterol and saturated fats.
Lack of Vitamins and Minerals in the Vegetarian Diet: How to Avoid It?
Speaking of important vitamins and minerals, because they are deficient in foods of plant origin or not highly bioavailable, the importance of including in the diet at least one of the 5 types of foods belonging to the first two basic food groups should be emphasized.
In fact, it is not vital, even if it is recommended, that they are all present in adequate quantities (neither excessive nor irrelevant). For this reason, a lacto-ovo-vegetarian diet, or only lacto-, or only ovo-, has a good chance of being balanced anyway; the same cannot be said for the vegan diet.
For further information: Supplements for Vegetarians and AGE more abundant in animal foods by over portioning some foods of the III, IV, VI and VII fundamental groups.But what are these anti-nutritional factors? Among the main ones we mention sequestrators or chelators and enzymatic inactivators: phytic acid, oxalic acid, trypsin inhibitors, dietary fibers and lecithins.
Phytic acid and phytates
Phytic acid is a six-fold repeated dihydrogen phosphate ester of inositol (del myo isomer), also called inositol hexakisphosphate (IP6) or inositol polyphosphate.
In vegetables (especially in the seeds of legumes, cereals and others), it has the nutritional role of storing phosphorus.
At physiological pH, the phosphates are partially ionized, giving rise to the phytate anion.
However, having a strong binding affinity with other minerals in the diet, such as calcium, iron and zinc, they can bind and inhibit intestinal absorption.
Cooking has a harmful action on the molecule by inactivating it. The soaking of the dried legumes allows to disperse a certain quantity.
Oxalic acid and oxalates
Oxalic acid is an organic compound with the formula C2H2O4, diffused in the form of dihydrate (C2H2O4 · 2H2O.).
It has an acid strength higher than acetic acid, constitutes a reducing agent and its conjugate base, known as oxalate (C2O2−4) represents a chelating agent for metal cations.
It is found naturally in many foods, but excessive dietary intake and even prolonged skin contact can be harmful.
It tends to bind mainly calcium and is abundant in the leaves of plants belonging to the family Chenopodiaceae (spinach, amaranth etc.), Brassicaceae (cauliflower, broccoli, kale, cabbage, etc.), Polygonaceae (rhubarb etc.), Arcaceae (Arisaema triphyllum), Apiaceae (sorrel, parsley, etc.), Vitaceae (American vine etc.), Oxalidaceae (carom) etc.
It should be noted that, on the basis of certain insights, citrus fruits produced in organic farming contain less oxalic acid than those produced in conventional agriculture.
The interest in this chelator also gravitates on the fact that the most common kidney stones are based on calcium oxalate; dietary therapy consists in the elimination of sources of oxalic acid, not calcium.
Again, cooking has a positive inhibiting effect.
Trypsin inhibitors
Trypsin inhibitors (TI), belonging to the serine protease group (serpin), are peptides that reduce the biological activity of trypsin by controlling its activation and catalytic reactions.
Trypsin is an enzyme involved in the breakdown of many proteins, mainly involved in the digestion of humans and other monogastric animals or young ruminants.
It is mainly contained in seeds such as legumes (especially soybeans) and cereals; its vegetal function is a deterrent towards animals and metabolic. It is also naturally present in the pancreas of some animals as a protective agent from the accidental activation of trypsinogen and / or chymotrypsinogen.
When taken with food, it acts as an irreversible and competitive substrate; in practice, it nullifies the proteolytic effect of trypsin.
Trypsin inhibitors also undergo heat degradation. Cooking eliminates its contents.
Dietary fibers
They are contained in all plants in their natural state.
Some dissolve in water, gel and slow down intestinal transit, others do not and are fermented by producing gas and stimulating peristaltic contractions.
Overall beneficial, because they increase satiety, modulating intestinal absorption, protect the intestine by lowering the risk of colon cancer, prevent constipation and related complications, nourish the intestinal bacterial flora, if in excess they hinder the uptake of useful molecules .
Too many fibers, in addition to being associated with higher levels of the other aforementioned antinutrients, can create both a hydrophilic and lipophilic mass (due to the presence of digestive fluids) capable of sequestering not only fats in general and cholesterol, but also essential lipids and fat-soluble vitamins ( vit. A, vit. D, vit. E, vit. K).
Lecithins
Lecithins is a controversial topic. Not everyone agrees on their potential anti-nutritional effect, or at least on the critical level.
Of great nutritional interest for their ability to limit the intestinal absorption of cholesterol and to positively affect its metabolism, they can however have an inhibiting effect on the intestinal uptake of other lipophilic molecules such as vitamins and essential fatty acids.
Some seeds, such as soybeans, are rich in lecithins, but also foods of animal origin such as egg yolk.
For further information: Sport and Vegetarian Diet: Benefits and Controversies ;Let's now see the most frequent cases of possible nutritional deficiencies related to the vegetarian diet.
Iron and anemia
Iron is an important mineral involved in several processes; the insufficiency in the diet is identifiable first of all by a reduced synthesis of hemoglobin of red blood cells and so-called iron deficiency anemia.
Highly bioavailable iron is abundant in meat, fish products and egg yolk. The intestine absorbs 20% of the ingested hemi iron and only 5% of ferrous iron.
Plant foods contain lower levels and usually very little bioavailable, both due to the chemical form, and due to any antinutrients.
Especially fertile and pregnant women have a greater need.
Vitamin B12 or cyanocobalamin
Vitamin B12 is involved in the synthesis of DNA, in the synthesis of red blood cells and regulates the metabolism of carbohydrates.
Although primarily of bacterial derivation, it is abundant in meat, fish and egg yolk. In vegetables it is almost absent and, in any case, not bioavailable.
The deficiency is very dangerous for the embryo-fetus, which risks irreversible malformations or abortion. It can also cause pernicious anemia.
Vitamin D
It is a pseudo-hormonal factor that regulates the metabolism of calcium and therefore of the bone in the body; it is also involved in immune defense.
Those who often and frequently expose themselves to sunlight in the spring, summer and autumn period independently produce sufficient quantities by exploiting cholesterol as a precursor.
Everyone else must get adequate amounts in their diet, so they consume fish and egg yolk.
Significant deficiency impairs the achievement of peak bone mass and is a risk factor for osteoporosis - but not only.
Football
We know that together with phosphorus it forms the basis of hydroxyapatite, a mineral of the skeleton, but it is also essential for various cellular processes.
It is very rich in milk and especially in seasoned derivatives, in a highly bioavailable form. In vegetables such as legumes it is present but lower and, moreover, conditioned in the absorption due to the presence of antinutrients.
A deficiency, rarer than that of vitamin D, can have an equal effect on the skeletal level (lack of or impaired growth and risk factor for osteoporosis).
Iodine
Its presence in food is so scarce that even omnivores tend to be deficient.
It underlies the synthesis of thyroid hormones.
It abounds in foods of marine origin; seaweed, for vegetarians, is the only useful nutritional source.
EPA and DHA
They are the most biologically active omega 3s.
Semi-essential for everyone, children, the elderly, pregnant women and nurses have a greater need.
They have such a high number of functions that it is impossible to summarize in a few lines; we limit ourselves to saying that they play the role of precursors of anti-inflammatory eicosanoids, are essential for the development and maintenance of the nervous and ocular, and that they have a protective metabolic impact from atherosclerosis.
The primary source is undoubtedly that of wild fatty fish. Eggs also contain not negligible levels. For vegetarians, it is a good solution to supplement with oil from algae.
Vitamin B2
Its deficiency is rare.
In the organism, it is the basis of the enzymatic cofactors FAD and FMN.
It is abundant in milk and derivatives but modest quantities are also found in vegetables.
Essential Amino Acids
Even this possibility of deficiency is quite remote for most lacto-ovo-vegetarians.
It is different for the sports population who embrace the vegan philosophy. In this case, the high biological value protein is almost always insufficient to support muscle protein turnover.
To remain compromised are therefore the post-exercise recovery and performance improvements, especially in strength activity. Food integration becomes indispensable.
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