Taste & Smell in Pregnancy
Your oral environment can influence many aspects of your health and the mouth can tell quite a story. Humans normally have between 5,000 and 10,000 taste buds, the majority of which are distributed on the tongue surface, palate, and epiglottis. And young children actually have more taste buds in their mouths than adults do. The bumps on your tongue (papillae) contain taste buds and each of these taste buds contain 50-100 neuroepithelial cells. The hair like threads (microvilli) that protrude bear the taste receptors. Your tongue is divided into sections that each have unique taste receptors which individually taste the main 5 tastes (sour, sweet, salty, umami and bitter) best. Taste is defined as a sensation caused by the chemical reaction of a substance with the receptors of taste cells. Yet, we truly cannot taste well unless we can also smell well. And if taste perception influences food intake, then assessing the ability to smell is very important.
Most any pregnant person can tell you that certain smells and tastes are not tolerated at key points throughout pregnancy. Although this might seem like a nuisance, it is thought to be a protective aspect of normal gestational progression even if it does mean taking one bite of a meal and leaving it or walking far away from tobacco smoke. Beyond pregnancy itself, there are diagnoses, commonly used medications, common nutrient deficiencies, genetic considerations, hormone modulation, environmental exposures, dental concerns (gingivitis and periodontal disease-common in pregnancy), physical trauma, and lifestyle choices that can also alter your normal sense of taste and smell.
In a particularly interesting study, it was found that overt Hypothyroidism* altered bitter taste, but once an intervention plan was in place, taste/smell returned to normal olfactory perception after 3 months. Why is this important? The ability to “taste” bitter normally is therapeutic and it’s not just your taste buds that have the ability to receive this most sensitive taste, but the ovaries, testes, liver and intestine also appear to “taste” bitter. The perception of bitter tastes in your liver may be linked to the detoxification process (via the TAS2 receptor family by way of CYP>CYP1A>AhR). Equally important is knowing that 25% of the population are super bitter tasters, meaning foods that contain bitter compounds (vegetables) are often not tolerated well and thus not consumed as often. For super-bitter tasters, bitter foods and high-calcium foods can cause a very unpleasant and gagging experience often having implications for overall health status. Bitter taste is found in high antioxidant and anti-carcinogenic rich foods, really important choices to include in the diet.
Normal or altered taste and smell can impact pregnancy and fetal development when we consider that:
1. People with altered taste and smell often tend salt their food more and add more sugar. There is solid data to suggest that early exposure to high fat, high salt and high sugar diets have long-lasting effect in the offspring.
2. Major nutrient deficiencies can mediate an altered sense of taste/smell, which impact a healthy and normal gestation (think B vitamins, zinc, copper, iron, iodine, and vitamins A, D and E)
3. High-calcium rich foods are necessary to meet this crucial mineral need in pregnancy
4. Around 18 weeks the fetus begins swallowing up to 1 L of amniotic fluid a day and all flavors that are consumed (liquid or solid) starting in the 2nd and more readily into the 3rd trimester are experienced by the fetus.
5. Initial experiences with tastes have an important role in the later enjoyment and acceptance of food by your growing child – based on the extensive work of Julie Mennella, PhD, what you eat during pregnancy and breastfeeding does translate to better acceptance at 6 months in a high chair.
How do you check if you have a normal or altered sense of smell? Or if you are a normal/super bitter taster?
It costs about $8.00 to check!
Smell Test: We use 4-Item NHANES pocket smell test
Taste Test: PTC (Phenylthiocarbamide) paper (easily found online)
We have found that consistently checking your taste and smell perception is an important part of your own empowered ability to optimize your wellness with two very simple (and inexpensive) tests.
Dr. Michael Stone is our key opinion leader and key medical consultant when it comes to understanding clinical indicators from the Nutrition Physical Exam. He is always reminding us that we must look in the mouth, as digestion, assimilation, absorption and biotransformation starts with the first steps behind the teeth.
*Overt Hypothyroid diagnoses currently occur in 0.3% of pregnancies while subclinical hypothyroidism occurs in 2-3%.
SOURCES:
Podzimek Š et al, Physiol Res. 2018 Nov 28;67(Suppl 3):S421-S429. doi: 10.33549/physiolres.934026. PMID: 30484669.
Baskoy K et al, PLoS One. 2016;11(2):e0149979. Published 2016 Feb 29. doi:10.1371/journal.pone.0149979
https://www.obgproject.com/2020/06/22/acog-update-thyroid-disease-in-pregnancy/
Loper HB et al, Nutr Rev. 2015;73(2):83-91. doi:10.1093/nutrit/nuu009