Generality
Pregnancy and clams: introduction
The doubt whether eating or avoiding clams is still gripping many pregnant women today.
It is well known that facing the gestation involves obligations and duties that are often essential. The mother must take on many responsibilities, including the abolition of all potentially risky behaviors and habits for the unborn child.
The clams, in addition to being very appreciated by all lovers of seafood, also have excellent chemical-food properties (thinness, richness in proteins, etc.). However, due to their nature, they are not free from hygienic and nutritional risks and contraindications. Being animals that feed on filtering sea water, from which they retain small nourishing algae, besides being rich in salt, it is inevitable that they act as a reservoir for unwanted elements.
Therefore, while on the one hand the clams contain many useful properties for health (including of the mother in pregnancy and the fetus), on the other hand they provide nutritional factors in excess or not entirely desirable.
For all these reasons, in principle, it is advisable to buy only live or frozen clams, from safe, certified supply sources, equipped with traceability and traceability. To further reduce the microbiological risk, it is advisable to cook them. Furthermore, it is also essential to consume them in the right portions and with a frequency of adequate consumption.
Pregnancy
Diet in pregnancy: foodborne illnesses and intoxications
Contracting foodborne illnesses and intoxications during pregnancy can be very dangerous, not so much for the mother as for the child. This statement does not intend to diminish the complications that may arise in the expectant mother, but it is a fact that fetal impairments have a higher level of severity. Among these, the main ones are:
- Fetal death
- Abortion
- teratogenicity
- Neuropathies and reduction of mental capacities
- Premature birth.
Damage to the child can be roughly divided into two categories:
- Direct lesions: the pathogen or toxin passes the placenta or placental barrier and infects the child
- Indirect offenses: negative influence of the pathology on the maternal organism, such as for example metabolic alterations, malnutrition and dehydration, high fever and severe inflammation, etc.
The list of parasites (worms and protozoa), bacteria, fungi, viruses, toxins and pollutants that can harm during pregnancy is long; below we will limit ourselves to mentioning the factors that could be transmitted by clams as food.
Clams
Overview of clams
Clams are small invertebrate animals belonging to the Phylum Mollusca and Classe Bivalvia. However, Vongola is a fairly vague term, as there are many similar creatures that fall into different family, genus and species.
Types of clams
In Italy mainly four types of clams are fished and sold locally: Venerupis decussata (clam verace), Venerupis philippinarum (Filipino clam), Chamelea gallina (common clam) and Dosinia sxoleta (lupine clam).
Quite similar to each other (but not identical), clams have more or less the same lifestyle:
- They stop at the seabed, lagoon and river mouths, under the sand or resting on it
- They filter the water from the siphons to eat the phytoplankton and from the gills to breathe
- They reproduce by pouring the gametes (both male and female) directly into free water
- In addition to humans, they are predated by animal species such as starfish and some fish
- To defend themselves, they seal the shells holding water inside the cavity; they can stay alive even a few days in the dry (at moderate temperatures).
Did you know that ...
The clams verace and Filipino become very large and live near the breaker, even on the mud; the clams common and lupine instead, are found above all on the sand and also more distant from the coast.
Clams as food
We eat the soft internal organism sealed in the shells of the clams. Free of sediments, pathogens and contaminants, clams can be eaten cooked (opening them directly in the pan) and, for healthy people NOT pregnant, even raw (opening them with the use of a small knife).
To eliminate sand from clams, making them healthier at the same time, it is common to subject them to housing. After picking, they are then left in special aquariums where clean water is purified "by filtering". This allows both to minimize the presence of sediments and to eliminate most of the pathogens and pollutants accumulated within them.
Clams and nutrients useful in pregnancy
We have said that clams are very nutritious foods. In pregnancy they can contribute to increasing the intake of high biological value proteins, specific vitamins and minerals of the fundamental group of foods.
Among the minerals, the importance of iodine stands out, a rare microelement that is present in significant concentrations only in sea foods. It is essential for the proper functioning of the thyroid and for fetal development.
As far as vitamins are concerned, clams are rich in many water-soluble factors of group B (mainly coenzymes), one of which is of vital importance for the growth of the child during gestation: vitamin B12.
Fats are not abundant (although they should have excellent "quality") and consequently fat-soluble vitamins. It is however possible that the level of vitamin D (cholecalciferol), necessary for the formation of the skeleton, and of retinol or equivalents (vitamin A or provitamins of the same kind - are almost never lacking in the diet during pregnancy) is appreciable.
The average portion of clams is between 50 and 100 g of edible portion (about 200-400 g of shelled clams).
Risks and Dangers
Pregnancy and clams: food safety hazards
Among the undesirable elements of clams we mention: algal biotoxins, viruses, bacteria and various pollutants.
Algal biotoxins in clams: do they hurt during pregnancy?
In Italy and generally in the Mediterranean Basin they are not a problem; in other seas instead (where other types of clams live), the presence of algal toxins can be very harmful to the health of consumers. The impact of algal biotoxins in pregnancy is little known, especially in the Mediterranean where we have seen it to be unlikely. However, very harmful algal biotoxins, present in other parts of the world, are related to fetal death, abortion, premature birth and malformations of various kinds.
Virus in clams: do they hurt during pregnancy?
We mainly talk about HAV, or the hepatitis A virus. Considered the least dangerous of all viruses that trigger viral hepatitis (in particular C and B), HAV is still capable of seriously damaging health. It dies with cooking. The danger does not increase dramatically during pregnancy (it is not associated with teratogenesis, abortion, etc.), since the chances of perinatal infection are minimal, but the disease can affect the unborn child by affecting it during childbirth.
Bacteria in clams: do they hurt during pregnancy?
It is the most dangerous and abundant category in clams. Among the clam bacteria are: Vibrio cholerae, Escherichia coli (various strains) and Salmonella ( typhimurium and enteritidis ). Abundant in the water polluted by the sewer system, all three and the related exotoxins ( protein in nature ) die / become inactivated with total cooking. However, some coliforms (Gram -) have the ability to produce endotoxins that can persist in clams even after heat treatment. In general, the bacteria that affect clams are the same as those due to fecal-oral contamination and responsible for severe gastro-enteric infections with vomiting, diarrhea, abdominal pain, etc. The damage of these pathologies on the fetus is above all indirect, due to maternal malnutrition, with dehydration, depletion of vitamin stocks etc.
Other bacteria, normally NOT present in clams, are much more dangerous and can cause direct injuries. This is the case of Listeria monocytogenes, typical of completely different foods (blue or molded cheeses, etc.).
Parasites in clams: do they hurt during pregnancy?
Parasitoses transmitted by clams to humans, contrary to what one might believe, are not many. Let's start by saying that the Anisakis, the dreaded marine worm that can be contracted by eating raw fish that has been dead for a long time, does not affect the clams. Then, it should be emphasized that any parasite dies totally by cooking or even only by freezing at - 20 ° C.
Abroad, there have been cases of zoonoses (protozoa), in particular Giardia and Cryptosporid ium, after eating raw clams.
In Italy protozoa and oocysts ( Giardia, Cryptosporidium and also Toxoplasma ) have been found in some samples of clams from the center of the peninsula. Although it was an isolated case, considering the danger of Toxoplasma in pregnancy, it is always advisable to cook clams. Giardia and Cryptosporidium should not cause direct damage to the fetus and are exclusively responsible for intestinal impairment in healthy people.
Pollutants in clams: do they hurt during pregnancy?
They mainly consist of heavy metals (mercury, lead, etc.) and residues from the breakdown of synthetic materials (polychlorinated biphenyls - PCBs - and dioxins). Heavy metals are generally scarce in molluscs, since they have a rather short life cycle. The concentration of synthetic pollutants on the other hand may vary from one area to another and depending on the time of year.
Mercury poisoning, which we reiterate to be unlikely by eating clams, is responsible for serious complications of the fetus. Babies born after large exposures to mercury and lead can show brain, kidney, etc. abnormalities.
While excessive exposure to PCBs seems to correlate, for the moment, only to a low birth weight, excessive amounts of dioxins can interfere with the sexual hormonal axis (consequently also with the thyroid one) compromising the general and cerebral development.
Obviously all the parameters are constantly monitored by the safety authorities. Moreover, their presence at sea is practically ubiquitous (they move with currents) and the only hypothetically effective method to reduce their concentration in clams could be the already mentioned housing.
In conclusion, it is essential for a pregnant woman who does not want to give up clams:
- Purchase them from reliable sources of supply (certified, controlled, with traceability and traceability, which regularly use livestock)
- Absolutely avoid raw clams, cooking them thoroughly, to minimize the risk of foodborne illnesses.
Pregnancy and clams: nutritional hazards
There are no real nutritional dangers related to the consumption of clams during pregnancy. It is however necessary to specify that these molluscs, containing sea water, are rich in sodium. Sodium is a mineral related to the worsening, in sensitive subjects, of the arterial hypertension disease. Since the onset and worsening of arterial hypertension (also called "gravidic") is frequent in pregnancy, it is recommended to:
- Discard the clam cooking water
- To consume clams in adequate portions and with sporadic frequency.
Furthermore, despite being lean, clams are not easily digested. They contain a lot of proteins but a part of them is constituted by the connective tissue. These fibers seem more resistant to the action of gastric juices and prolong digestion times. It is therefore necessary to avoid or reduce them significantly in the case of ulcers and gastritis. Furthermore, complications of digestion and related small disorders often arise during pregnancy, for example: hiatal hernia, gastroesophageal reflux disease and dyspepsia. For this reason it is recommended, once again, to consume the clams with moderate portions and frequency.
For those suffering from hypercholesterolemia, the cholesterol in clams may be too abundant.
