At the beginning of today's article, I would like to let you do a quiz:
(Click Vote to see everyone's voting results)
Maybe when many people do the second question, they will think that my parents are still clean, and there will definitely be no smell on the body when they are old.
Is this really the case?
No, because the "old man's flavor" is not that you think too much, but that it really is.
Studies have shown that with age, the body emits a flavor molecule called 2-nonalaldehyde, which can only be detected on the surface of the skin of people over 40 years old [1].
The substance smelled like clothes that hadn't been washed in years, a greasy smell, or a smell of moldy weeds. The two flavors blend together and are likely to be the source of the "old man's taste".
It is said that this "old age" taste becomes stronger with age.
Because 2-nonalaldehyde comes from the oxidation and degradation of omega-7 unsaturated fatty acids, with the increase of age, the human body will produce more omega-7 unsaturated fatty acids, which will produce more odorous 2-nonalaldehyde and produce more "odor molecules".
In addition to the substance 2-nonal, which will make the elderly smell, there are also some reasons from diet, living habits, and diseases, which will also make their body odor more obvious. In particular, some people are more likely to suffer from chronic diseases as they get older.
For example, diabetics produce ketone bodies during metabolism, which smell like rotten apples [2].
In patients with chronic kidney disease and kidney failure, some of the metabolites of nitrogen-containing substances in the body will be emitted through breathing and sweating, which smells like salted fish [3].
In case of some dental disease, such as caries, periodontitis, etc., they also have an indescribable odor in their mouth caused by the overbreeding of bacteria.
You may think, if you are healthy, then it will be tasteless?
The answer is still no.
If there is alcoholism, smoking or poor living and eating habits, the bacteria that cause bad breath in the mouth will increase relatively, and the "taste" will be greater. This also explains why there are many young people who come with their own flavor blessings wherever they go.
Seeing this, you will most likely find that many times the "old man's taste" is actually not something they can decide, but the disease finds them.
You may be curious to think, we ourselves for two days without washing our hair, we can be choked by the oil head to tears, these old people can not smell their own body?
Yes, it's not that they don't want to admit that the same smell we can smell, the old man may not really smell. (After all, if they really perceive it, who wants to go out with the smell?) ）
So the question is, why can't the old man smell his own odor?
Everyone has an "odor threshold" for each odor, which is the minimum concentration at which this odor can be smelled by the human body.
The lower the "odor threshold", the more sensitive a person's nose is.
Studies have found that the "odor threshold" in older people is generally 2 to 15 times higher than that of young people [6].
That is to say, people are getting older, their olfactory function will gradually weaken, and the nose's recognition and discrimination of odors will become less and less sensitive.
In particular, the loss of smell in the elderly who suffer from certain diseases, such as Alzheimer's disease and Parkinson's disease, will be more severe.
There is another condition that also affects their ability to smell their own odor: the human sense of smell is adaptive.
Even if a certain odor can be recognized at the beginning, if you stay in this odor environment for a long time, you will not be sensitive.
Because of physical reasons, the "strange smell" of the old people will always accompany and gradually increase, this process is like boiling frogs in warm water, it is difficult for them to smell themselves.
If you still don't understand, you can smell the perfume spray on the body of those who can "choke people", usually they will say that the feeling is not very heavy, they are not aware of it at all.
As we said earlier, there are many reasons for the production of old age.
If the odor caused by aging or disease may not be completely eliminated, we can alleviate it in some ways. Like what:
1. Take a shower and change your clothes
Remind or assist the elderly to bathe frequently (if possible, at least once every two days);
Buy more clothes for the elderly to change, remind them that they can change often (it is better to change directly after bathing, do not wait until there is a clear smell before changing);
Take time to go to the old man's home and open the window for the old man to ventilate.
2. Do what you can
As long as the physical condition allows, the elderly can be advised to do more exercise.
On the one hand, this can reduce the risk of various chronic diseases, can maintain the normal function of the liver and kidneys for a longer time, on the other hand, it can also reduce the body odor due to organ function damage.
It is generally recommended that the elderly complete at least 150 minutes of moderate-intensity aerobic physical activity per week (e.g., brisk walking, dancing, gardening, etc.) or at least 75 minutes of high-intensity aerobic physical activity per week (e.g., running, climbing, etc.) [7,8].
3. Pay attention to living habits and control weight
If you are overweight, the probability of developing diabetes increases a lot, and the probability of "old age" also increases [7].
Be sure to control your weight, not only need the necessary amount of exercise, but also pay attention to a balanced diet, eat less fried and other high-calorie foods.
At the end of the article, I would like to say a few words:
The smell of the elderly does stink, and it may also be the smell of a variety of unpleasant smells.
But please don't abandon and alienate them.
After all, each of us may become the next one.
I hope that everyone who reads this article can give the elderly a little more tolerance and love.
Special Author: Zhang Hongtao (pen name Section Ginger)
Associate Professor of Research, Department of Pathology and Experimental Medicine, University of Pennsylvania School of Medicine, USA
bibliography
[1] Haze, S., et al., 2-Nonenal Newly Found in Human Body Odor Tends to Increase with Aging. Journal of Investigative Dermatology, 2001. 116(4): p. 520-524.
[2] Minh, T.D.C., D.R. Blake, and P.R. Galassetti, The clinical potential of exhaled breath analysis for diabetes mellitus. Diabetes Research and Clinical Practice, 2012. 97(2): p. 195-205.
[3] Davies, S.J., P. paněl, and D. Smith, Breath analysis of ammonia, volatile organic compounds and deuterated water vapor in chronic kidney disease and during dialysis. Bioanalysis, 2014. 6(6): p. 843-857.
[4] Rosenberg, M., T. Knaan, and D. Cohen, Association among Bad Breath, Body Mass Index, and Alcohol Intake. Journal of Dental Research, 2007. 86(10): p. 997-1000.
[5] Wu, J., et al., Halitosis: prevalence, risk factors, sources, measurement and treatment – a review of the literature. Australian Dental Journal, 2020. 65(1): p. 4-11.
[6] Schiffman, S.S., Taste and Smell Losses in Normal Aging and Disease. JAMA, 1997. 278(16): p. 1357-1362.
[7] World Health Organization, Physical Activity Recommendations for Adults 65 Years of Age and Older. https://www.who.int/dietphysicalactivity/factsheet_olderadults/zh/
[8] World Health Organization, what are moderate and intense physical activity? https://www.who.int/dietphysicalactivity/physical_activity_intensity/zh/
Curated: Hammer Hammer
Editors: Zhao Yanan, Zhang Li, Zhang Jie
Typesetting: Han Ningning | Proofreader: Wu Yihe
Operations: Li Yongmin | Coordinator: Wu Wei