Thumb sucking in children is a protective mechanism against allergies

Sucking the thumb can protect against allergies
Actually, yes children are told that they should not suck on her thumb or chew off her fingernails. Researchers have now discovered, however, that so-called thumb sucking and fingernail chewing mean that sufferers in later life are less likely to have certain allergies.

Children love to suck on their thumbs and chew on their fingernails. Usually, they then hear from their parents that they should stop. However, scientists from the University of Otago and McMaster University have now found out in a research that sucking thumbs and chewing fingernails can protect against developing certain allergies later in life. The physicians published the results of their study in the journal "Pediatrics".

Parents keep telling their children not to suck their thumbs or chew their fingernails. Researchers now discovered that these bad habits can protect us from allergies later in life. (Image: evasilchenko / fotolia.com)

Early exposure to dirt and germs reduces risk of allergies
Sucking thumbs and chewing fingernails are habits that already develop babies in the womb. Thus, they are protected as a teenager from various allergens, say the doctors. These include, for example, house dust mites, grass, mold and hair of animals. When children are exposed to such germs, their body's immune functions change. Our findings are consistent with hygiene theory that early exposure to soil and germs reduces the risk of developing allergies, explains author Professor Malcolm Sears.

Childhood habits help us in adulthood
The "negative" habits of childhood also help us in adulthood. Even if children already suffered from allergies and grew up in a house where there were pets or the parents smoked, the experts say. Of course, we do not now recommend that children should be encouraged to adopt these habits, but at least there seems to be a positive side, says Professor Sears of McMaster University in Canada.

Physicians observe volunteers from birth to the age of 32
The new study was conducted by the University of Otago in New Zealand and McMaster University in Canada. The scientists studied 1037 participants from birth to adulthood. For this, the parents of the children reported habits such as thumb sucking and nail biting at the age of five years, seven years, nine years and finally at the age of eleven years. Tests for a common allergen were carried out at the age of 13 and 32 years, say the experts. The physicians used a so-called prick test. With the help of this skin test the suspicion of an increased readiness for allergies can be confirmed or a sensitization can be excluded.

Protective effect in 13-year-old children
The results of the study show that children who sucked on the thumb or chewed on their fingernails, showed less allergies at the age of 13, compared with children who barely sucked on the thumb. 38 percent of the thumb suckers suffered from allergies, compared to 49 percent from the control group. If children had both habits regularly, their risk dropped to 31 percent, say the authors.

Allergy risk in later life decreases when children are exposed to different microbes
This protective effect was retained even if the subjects were already 32 years old. The protective effect was still at the same level at this age, the experts explain. The new findings suggest that our risk of allergies later in life decreases when we're exposed to different microbes as a child, says lead author Professor Bob Hancox.

No advantage in the risk of asthma and hay fever detected
However, even if thumb sucking and nail biting led to the development of fewer allergies in the skin tests performed, no difference was found for the risk of allergic diseases such as asthma or hay fever, the researchers add. (As)