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Some weird food experiences can easily be explained by science. Yagi Studio/Getty Images

Medical News Today looks at why some people have such a strong aversion to cilantro, why we experience the “amazing nastiness” of orange juice after brushing our teeth, and more.

Have you ever met someone who complained about cilantro tasting like soap? Did you think it was an exaggeration? Or, how many times have you gone to drink some orange juice, only to find that it tastes appalling because you had just brushed your teeth?

Intrigued by these peculiar experiences, Medical News Today asked nutritionists and dieticians to shed light on the science behind the sensations.

We spoke with Dr. Jerry Bailey, certified nutritionist and acupuncturist, and chiropractic and functional medicine physician at Lakeside Holistic Health — and with Stephanie Klein, a registered dietitian, licensed nutritionist, and clinical director of diabetes prevention and reversal at Simplex Health.

A cilantro ‘soap’ gene?

Cilantro, also known as coriander or Chinese parsley, is a leafy green vegetable and herb, and one that is very divisive. The seeds feature in a range of Indian and Mexican dishes, but for the many people out there who love this herb, there are just as many who hate it.

The hate, it seems, stems from the chemicals inside cilantro and a variation in olfactory receptor genes that some people have. These individuals say that cilantro smells pungent and leaves a rather soapy taste in the mouth. This is different from the strong citrus notes that others taste.

“[The genetic variant] OR6A2Trusted Source may be the olfactory receptor gene that contributes to the identification of soapy smell. So, it may serve as the root for the soapy taste of cilantro leaves,” said Dr. Bailey.

He added that some people are highly sensitive to a group of chemicals called aldehydes and specifically to (E)-2-alkenals and n-aldehydesTrusted Source, the culprits behind that unpleasant soapy taste.

Another cause of the soapy taste could be the aroma and flavor compound S-linalool, a major component of the oils in this herb, Dr. Bailey explained.

“More than 60% of perfumed cleaning agents and hygiene products contain S-linalool. Pest professionals use it in the preparation of insecticides, and mosquito repellent products also make use of linalool,” he said.

Nowadays, some genetic testing sites even give people the option of seeing whether they are genetically predisposed to dislike cilantro.

Nausea after green tea in the morning

Green tea contains many polyphenolsTrusted Source, including flavanols, flavonoids, phenolic acids, catechins, and tannins. Thanks to its nutrient- and antioxidant-rich makeup, this tea can bring a range of health benefitsTrusted Source.

However, not everyone can or should drink it. Some people, for example, may notice gastrointestinal problemsTrusted Source shortly after they have even one cup.

One of the most common problems is nausea, especially if people have the tea before breakfast.

Dr. Bailey explained that the tannins in green tea can cause stomach irritation, which could explain the discomfort.

“If green tea is brewed too strongly or consumed on an empty stomach, these tannins increase dramatically, which in turn, increases the amount of acid production in your stomach. This increase in excess acid can lead to digestive issues, including constipation, acid reflux, and nausea.”

– Dr. Jerry Bailey

To avoid this, brew or steep green tea in water that is not too hot: 160–180ºF is best.

“It’s easy to avoid these side issues by not drinking green tea on an empty stomach. Instead, consume green tea during or after each meal,” Dr. Bailey continued.

He warned that because of this increase in acid production, people with acid reflux, stomach ulcers, or other digestive issues should avoid green tea. “As always, be sure to consult with a qualified functional medicine provider who understands your health before adding green tea into your diet if you are concerned,” he added.

Chalky ‘spinach teeth’

This weird yet common phenomenon involves having a fuzzy, chalky, or gritty feeling inside the mouth after eating spinach, raw or cooked. In combination with yogurt, the effect may be even stronger.

Unpleasant as it is, this is a harmless effect of eating greens that are “chock-full of oxalic acid,” said Dr. Bailey.

“When we chew spinach, the oxalic acid combines with calcium from the spinach and other foods in the mouth. The reaction between these two chemicals leads to the formation of calcium oxalate,” he explained.

These tiny crystals then float around in the mouth, which causes that rough, sticky texture of the teeth.

“Calcium oxalate is a tiny crystal that doesn’t dissolve well in water, which is why many feel this grainy texture in [their] mouths.”

– Stephanie Klein

Klein told MNT that this sensation is more common after eating spinach because the vegetable has such high levels of a natural compound called oxalic acid, or oxalate.

Calcium oxalateTrusted Source” may be familiar to anyone who has had kidney stones, and it is the most common component in these stones, Klein explained, adding, “This is why dietitians advise those susceptible to kidney stones to limit high oxalate foods, like spinach.”

Getting rid of calcium oxalate, however, is simple. Dr. Bailey recommends boiling or steaming spinach or squeezing some lemon juice on the fresh leaves. In the latter example, the ascorbic acid, or vitamin C, in the juice helps dissolve the oxalic acid.

The OJ-toothpaste dilemma

Drinking orange juice after brushing the teeth can leave a nightmarishly bitter taste. This can be explained by one thing, a common ingredient that has become notorious for stripping the skin of its natural oils: sodium lauryl sulfate (SLS).

“[SLS] is a surfactant, or what is known as soap. Besides toothpaste, it is found in a variety of household products, including bubble bath, lip balm, and shaving cream, to name a few. The SLS is what creates the foam while you brush,” Dr. Bailey explained.

SLS in toothpaste ruins the taste of orange juice in two ways, he continued.

“One, it suppresses the ‘sweet’ receptors on the taste buds, thus making you temporarily unable to taste any sweet flavors. Two, since it is a soap, it breaks down phospholipids, which are agents that block the ‘bitter’ receptors on your tongue.”

“This is why you only taste the bitterness and citric acid in orange juice, [not] any sweetness,” Klein added.

To avoid this, Klein recommended using a toothpaste that is free from SLS or drinking the juice well before brushing the teeth.

SLS is also linked withTrusted Source skin sensitivity and irritation in people who have skin conditions such as perioral dermatitis.

Swollen lips after salty snacks

After eating particularly salty foods, you may have noticed a whiteish ring in the inner parts of your lips or just a general feeling of fullness in your lips. This might happen hours after eating salted sunflower seeds, for example, a common snack in the Middle East.

Although a lot of swelling accompanied by other local or systemic reactions could point to something more serious, such as an allergy, a little swelling is nothing to fear.

“It is common for lips to swell upon waking if you have consumed large amounts of salt the prior night,” Dr. Bailey told MNT.

“The increase in salt consumption from foods like salted popcorn, sunflower seeds, chips, or other high salt-containing processed foods causes the body to retain fluid, which may also cause swelling in the eyelids and the lips. This can give you that morning puffiness look, swollen and often described as ‘allergy face.’”

– Dr. Jerry Bailey

To eliminate or reduce the effect, Dr. Bailey suggested that people avoid having saltier foods later in the evening. He also recommended unsalted popcorn or making vegetable chips with a food dehydrator.

Klein warned that a handful of popcorn or sunflower seeds should not result in swollen lips, but that this can happen if a person takes in excessive amounts of salt.

“Consuming too much salt leads to fluid retention, which for some can result in unwanted swelling in parts of the body. The body needs a happy balance of sodium and water in our blood. So, too much of one will cause an imbalance of the other,” Klein explained.

“Eating a variety of whole foods will usually provide all of the essential minerals we need in the right balance, ensuring we maintain a healthy equilibrium in the body,” she noted.

Source: Chalky spinach, soapy cilantro: 5 weird food phenomena explained