Scents are an important part of life. They affect our emotions and wellbeing. We are constantly exposed to scents, whether natural or synthetic. Some we seek out, others we try to avoid.
A wide range of scents and scented products are marketed as healthy, and we hear that they will improve our wellbeing.
However, it is worth being informed about what is and what may not be healthy.
In the natural world, scents are used to attract and to repel.
Sweet-smelling flowers draw insects that help plants to propagate. Malodorous plants and animals keep predators at bay, while hazardous items, such as rotting meat, tell us by their smell that they are not edible. Cats and dogs spray to mark their territory, and they recognize each other by smell.
Humans are believed to give off substances known as pheromones in their bodily excretions, which could play a role in sexual attraction and reproduction.
The existence of pheromones as part of sexual attraction has not been confirmed, but it seems likely that humans, like other animals, have historically used body odors to attract and recognize each other.
One researcher has suggested that bodily odors are processed differently in the brain than other odors.
Scents are produced and used in a variety of ways for a range of purposes.
- growing roses in the garden for enjoyment
- masking unwanted smells, for example in deodorants, household cleaners, and garbage bags
- enhancing or attracting
- making a fashion or identity statement, as with perfumes
- providing a pleasant environment, for example, pot pourri
- repelling insects, for example, citronella
- clearing the sinuses, for example, menthol and eucalyptus on a handkerchief
- improving mood and well-being, as with aromatherapy oils
- whetting the appetite
- selling products, as with the use of nebulization technology in sensory marketing, to disperse the smell of baking bread or fresh coffee at the entrance of a grocery store
Scents may work as a pain reliever, either by distracting from the pain, or because they activate opioid receptors in brain.
Aromatherapy researchers are actively finding more effective essential oils that work through smell.
Smells affect us on psychological, neurological, emotional, or physiological levels, or a combination of all.
They affect the emotions, for example, by triggering memories, and they may affect health and mood because of their molecular action.
When something gives off a scent, it releases tiny molecules into the air. As these enter the nose, they reach nerve cells known as olfactory sensory neurons.
These neurons send signals to the brain through the olfactory bulb, which runs alongside the brain. The brain receives the signal and identifies the scent.
The parts of the brain that receive these messages are the amygdala and the hippocampus. Smell signals pass through these on the way to the thalamus. The amygdala and the hippocampus play a role in processing emotions and memory. Sound and touch do not pass through these areas. They pass straight to the thalamus.
In this way, particular smells can trigger a powerful memory in the way that other senses do not.
The smell of pine, freshly cut grass, or a particular hand lotion may take us back to the comfort of our childhood days.
The whiff of diesel fumes or manure may turn the stomach of many, while triggering happy memories for others.
Medications affect our bodies in different ways. Smells can have a similar influence.
Drugs taken by mouth enter the bloodstream through the digestive system. When an inhaler or a eucalyptus vapor bath is used, the molecules enter the bloodstream through the lungs.
The effect of the smell depends on which molecules are involved. Some scents are known to be calming or stimulating, or they may have other effects.
A wide range of scents in the form of candles, cosmetics, and oils make a number of health claims. In some cases, research supports the claims.
In 2016, researchers from the University of Northumbria in Newcastle, United Kingdom (U.K.) presented findings showing that peppermint, chamomile, rosemary, and lavender can affect mood and memory.
Peppermint enhances and aroused mood and thinking ability, improved both long-term and working memory, and increased alertness.
Chamomile had a calming, sedative effect, and it slowed memory and attention speed.
Rosemary can improve memory scores in tests by 15 percent or more.
Lavender boosted calmness and contentedness and reduce the likelihood of remembering to perform a task at a specific time.
Studies in a health care setting have associated lavender essential oil with a relaxation effect and lower job stress in nurses, and improved sleep quality and reduced anxiety in cardiac patients in an intensive care unit (ICU).
Other research has indicated that:
Electroencephalogram (EEG) recordings have supported these findings.
Researchers in Germany have found that the scent of jasmine can have an action similar in strength to commonly prescribed barbiturates. They noted a soothing, calming effect, and suggest that it could be used as an alternative to sleeping pills or mood enhancers.
Can scents help in weight loss?
Olive oil as an aroma was found to improve the sense of satisfaction in participants who ate yogurt enriched with an essence of olive oil. Participants took in fewer calories each day over 3 months compared with a control group.
Another study found that subjects to consumed zero-fat yogurt experienced a drop in serotonin levels and lower satisfaction with their food, compared with those who consumed zero-fat yogurt with olive oil aroma.
Vanilla, according to anecdotal evidence may provide the same pleasure as tasting something sweet. In this way, it could reduce the risk of overeating, potentially resulting in weight loss.
Sweet smells, argue proponents, may stimulate the opioid receptors in the brain, just as sugar does. Instead of consuming sugar, the individual can get the same pleasure from a sweet scent.
However, the sweet smell could also tempt the person to eat something sweet, if they are hungry.
If more studies confirm this theory, adding an essence of vanilla or olive oil to food instead of sugar or fat could help people who want to lose weight.
It is important to note that essential oils should never be swallowed or applied directly to the skin. They should be diluted in a carrier oil.
Many shops sell candles, cosmetics, and other scented products to promote health, but not all of them are healthful.
The United States (U.S.) Food and Drug Administration (FDA)
The fact that a product contains "essential oils" does not guarantee that it is safe, free of other hazardous ingredients, or that it contains any particular concentration of the oil.
The FDA urges people to research the ingredients in the products they select, and to report any adverse effects, if these are not clearly explained on the label.
The chemicals used to create or deliver a fragrance can also be unhealthy.
Ethanol, acetone, benzaldehyde, benzyl alcohol, linalool and camphor are used in scents that have been studied for possible health effects.
Scented products such as perfumes and colognes can trigger asthma attacks in some people, or skin and eye irritation in sensitive individuals. Oils and perfumes applied directly to the skin can cause blisters and allergic reactions in some people, even if the oils are natural. Essential oils should be mixed with a carrier oil before applying to the skin.
In 2001, the Environmental Protection Agency (EPA) warned that scented candles and incense can be a source of indoor air pollution, producing high levels of particulate matter, or soot, lead, and other chemicals that have been linked to health problems, including respiratory problems and skin irritation.
A 2009 study showed that the use of paraffin wax in candles, even without scent, produced potentially harmful chemicals, such as alkans, alkenes, and toluene. Frequent use could contribute to cancer, allergies, and asthma.
Vegetable-based candles, such as those made from soy wax, did not produce these toxic chemicals.
The use of air fresheners that contain phthalates during pregnancy could have a damaging effect on fetal development, possibly leading to childhood asthma in the future, says another study, although this is not confirmed.
Some countries have triggered initiatives for scent-free workplaces.
The Canadian Center for Occupational Health and Safety (CCOHS) lists a number of negative reactions experienced by people who cannot tolerate scented products.
- dizziness and nausea
- loss of appetite
- confusion and depression
- respiratory problems and shortness of breath
To minimize the risk of reactions in employees with environmental sensitivities, employers are urged to consider the need to accommodate this type of special need.
- carrying out an assessment to determine the extent of the problem
- creating a policy to reduce or remove scents from the workplace
- ensuring that people know the rules about avoiding perfumes, deodorants, and any other product that may produce a scent
- putting up "scent-free" signs and ensuring that both regular employees and visitors adhere to the rules
- providing wipes for people to remove any trace of scent before entering the environment
Employees who are especially sensitive to smells should ask their employer about taking such actions.
What can I do if scented products bother me?
Many unscented or scent-free personal care or household products are available on the market, but users should still test these products for possible irritation before use.
Even in a product with no added fragrance, an odor may come from another ingredient.
Alternatives to household products include baking soda for cleaning, for example.
Personal care products or aromatherapy oils should not be used on broken or infected skin areas, and essential oils should never be applied without first diluting them and carrying out a patch test.
Essential oils should never be swallowed, as they can be toxic.
Scented oils can also trigger reactions such as asthma, skin rashes, headache, liver, and nerve damage. Anyone experiencing these reactions should stop using the product, and, in severe cases, consult a doctor.