Clams in Pregnancy

Clams in Pregnancy


Pregnancy and clams: introduction

The doubt whether to eat or avoid clams still grips many pregnant women today.

It is well known that dealing with pregnancy involves obligations and duties that are often unavoidable. The mother has to take on many responsibilities, including the abolition of all potentially risky behaviors and habits for the unborn child.Clams, in addition to being highly appreciated by all seafood lovers, also have excellent chemical-food properties ( leanness , richness in protein , etc.). However, due to their nature, they are not without risks and contraindications of a hygienic and nutritional nature. Being animals that feed by filtering sea water, from which they retain small nutritious algae , as well as being rich in salt , it is inevitable that they act as a reservoir for unwanted elements.

Therefore, if on the one hand clams contain many properties that are useful for the health (also of the pregnant mother and the fetus ), on the other hand they bring excess or not entirely desirable nutritional factors.

For all these reasons, in principle, it is advisable to purchase only live or frozen clams, from safe, certified sources of supply, 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 adequate frequency of consumption.


Diet in pregnancy : foodborne illnesses and poisoning

Contracting foodborne illnesses and food poisoning during pregnancy can be very dangerous, not so much for the mother as for the child. This statement does not intend to minimize the complications that can arise in the pregnant woman, but it is a fact that fetal compromises have a higher level of seriousness. Among these, the main ones are:

  • Fetal death
  • Abortion
  • Teratogenesis
  • Neuropathies and reduced mental abilities
  • Premature birth .

Damages to the child can be roughly divided into two categories:

  1. Direct injury: Pathogen or toxin crosses the placenta or placental barrier and infects the baby
  2. Indirect offenses: Negative influence of pathology on the maternal organism, such as metabolic disorders, 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 pregnancy is long; below we will limit ourselves to mentioning the factors that could be conveyed by clams as food.


Overview of clams

Clams are small invertebrate animals that belong to the Phylum Mollusca and Classe Bivalvia. Clam is however a rather vague term, as there are many similar creatures that fall under different Family, Genus and Species.

Types of clams

In Italy, mainly four types of clams are fished and marketed locally: Venerupis decussata (verace clam), Venerupis philippinarum (Philippine 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 life habits:

  • They stop at the seabed, lagoon and river mouths, under the sand or resting on it
  • They filter water through siphons to eat phytoplankton and gills to breathe
  • They reproduce by pouring the gametes (both male and female) directly into free water
  • In addition to humans, they are preyed upon by animal species such as starfish and some fish
  • To defend themselves, they seal the shells by retaining water inside the cavity; they can also stay alive for a few days in dry conditions (at moderate temperatures).

    Clams as food

    Of the clams you eat the internal soft organism sealed inside the shells. Free of sediments, pathogens and contaminants, clams can be eaten cooked (by opening them directly in a pan) and, for healthy people NOT pregnant , also raw (by opening them with the use of a small knife).

    To remove the sand from the clams, making them healthier at the same time, it is common practice to subject them to relaying. After sampling, they are then left in special aquariums where they are purified by “empty filtering” the clean water. This allows both to minimize the presence of sediments and to eliminate most of the pathogens and pollutants accumulated inside them.

    Clams and nutrients useful in pregnancy

    Clams, as we said, are very nutritious foods . During pregnancy they can help to increase 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 very rare microelement and present in significant concentrations only in seafood. It is essential for proper thyroid function and 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 pregnancy: vitamin B12 .

    Fats are not abundant (although they should have an excellent “quality”) and consequently fat-soluble vitamins . However, it is possible that the level of vitamin D (cholecalciferol), necessary for the formation of the skeleton , and retinol or equivalent ( vitamin A or provitamins of the same kind – are almost never deficient in the diet during pregnancy) are appreciable.

    The average portion of clams is between 50 and 100 g of edible portion (about 200-400 g of clams in their shells).

    Risks and Dangers

    Pregnancy and clams: food hygiene dangers

    Among the unwanted elements of clams we mention: algal biotoxins, viruses, bacteria and various pollutants.

    Algal biotoxins in clams: are they bad for 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 poorly understood, 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.

    Viruses in clams: are they bad for pregnancy?

    We are talking above all about HAV, or the hepatitis A virus . Considered the least dangerous of all the viruses that trigger viral hepatitis (particularly C and B), HAV is nonetheless capable of seriously harming health. Dies with cooking . The danger does not increase dramatically during pregnancy (it is not associated with teratogenesis, abortion, etc.), since the chances of perinatal contagion are minimal, but the disease can affect the unborn child during delivery.

    Bacteria in clams: are they bad for pregnancy?

    It is the most dangerous and abundant category in clams. Among the clam bacteria, the following are particularly implicated: Vibrio cholerae , Escherichia coli (various strains) and Salmonella ( typhimurium and enteritidis ). Very abundant in polluted waters from the sewage system, all three and the relative exotoxins ( of a protein nature ) die / are inactivated with total cooking . However, some coliforms (Gram -) have the ability to produce endotoxins which can persist in the clams even after heat treatment. Generally, the bacteria affecting the clams are the same ones spread by fecal-oral contaminationand responsible for serious gastro-enteric toxin 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, NOT normally found in clams, are much more dangerous and can cause direct injury. This is the case of Listeria monocytogenes , typical of completely different foods ( blue or moldy cheeses, etc.).

    Parasites in clams: are they bad for pregnancy?

    The parasitic diseases transmitted by clams to man, contrary to what one might believe, are not many. Let’s start by saying that Anisakis , a dreaded marine worm that can be contracted by eating raw fish that has been dead for a long time, does not affect clams. Then, it should be emphasized that any parasite dies totally with cooking or even with freezing at -20°C.

    Abroad there have been cases of zoonoses (protozoa), in particular Giardia and Cryptosporidium , 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 the clams. Giardia and Cryptosporidium should not cause direct damage to the fetus and are exclusively, in healthy people, responsible for intestinal compromise.

    Pollutants in clams: are they bad for pregnancy?

    They are mainly made up of heavy metals ( mercury , lead , etc.) and residues from the decomposition of synthetic materials (polychlorinated biphenyls – PCBs – and dioxins ). Heavy metals are generally scarce in molluscs , as they have a rather short life cycle. The concentration of synthetic pollutants, on the other hand, can vary from one area to another and according to the time of year.

    Mercury poisoning, which we reiterate is unlikely by eating clams, is responsible for serious complications in the fetus. Babies born after heavy mercury and lead exposure may show brain, kidney, etc. abnormalities.

    While excessive exposure to PCBs seems to be related, for the moment, only to low birth weight , excessive amounts of dioxins can interfere with the sexual hormonal axis (consequently also with the thyroid one), compromising general and cerebral development.

    Obviously all the parameters are constantly monitored by the safety bodies. Moreover, their presence in the sea is practically ubiquitous (they move with the currents) and the only hypothetically effective method to reduce their concentration in clams could be the already mentioned relaying.

    In conclusion, for the pregnant woman who does not want to give up clams it is essential:

    • Buy them from reliable sources of supply (certified, controlled, tracked and traceable, which make regular use of housing)
    • Absolutely avoid raw clams, cooking them thoroughly, to minimize the risk of foodborne illness.

    Pregnancy and clams: nutritional dangers

    There are no real nutritional dangers associated with the consumption of clams during pregnancy. However, it must be specified that these molluscs, containing sea water, are rich in sodium . Sodium is a mineral related to the worsening of arterial hypertension disease in sensitive subjects . Since the onset and worsening of arterial hypertension (also called “pregnancy”) is frequent during pregnancy, it is recommended to:

    • Throw away the cooking water from the clams
    • To consume clams in adequate portions and with sporadic frequency.

    Furthermore, despite being thin, clams are not easily digestible foods . They contain many proteins but a part of these is made up of connective tissue. These fibers seem more resistant to the action of gastric juices and prolong digestion times . It is therefore necessary to avoid them or reduce them significantly in case of ulcer and gastritis . In addition, digestive complications and minor related disorders often arise during pregnancy , for example: hiatal hernia , gastroesophageal reflux disease and dyspepsia. For this reason it is recommended, once again, to consume clams in moderate portions and frequency during pregnancy.

    For subjects afflicted with hypercholesterolemia , the cholesterol in clams could be too abundant.



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