Many people have this feeling: every time they go to the old people's home, they always feel a strange smell. In places where there are many elderly people, there will also be some taste.
This smell seems to be unique to the old man. But the old man himself could not smell it at all...
It does exist.
Among the various odor molecules emitted from the human body, there is a substance called 2-nonalaldehyde, which tastes unpleasantly greasy and curd. Studies have shown that this odor molecule, called 2-nonalaldehyde, can only be detected on the surface of the skin of people over the age of 40 [1].
2-nonaldehyde comes from the oxidation and degradation of omega-7 unsaturated fatty acids, and with the increase of age, the human body will produce more omega-7 unsaturated fatty acids, which will produce more odorous 2-nonanaldehyde.
There are also some factors from diet, living habits, and diseases, which can also lead to an increase in body odor.
In particular, the risk of some chronic diseases increases with age, so it is also associated with the "old man's taste".
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For example, diabetics produce ketones during metabolism, which is a molecule with a rotten apple flavor [2].
For example, in patients with chronic kidney disease and kidney failure, some of the metabolites containing nitrogen in the body cannot be excreted with urine, and they will also be emitted through breathing and sweating, which will release a salted fish-like rotten corpse smell [3].
In addition, in patients with oral diseases such as caries and periodontitis, because the bacteria in the mouth over-multiply, the metabolites produced will also emit a foul odor, which is a common cause of bad breath.
In people who drink and smoke, the bacteria in the mouth are even more "not talking about martial virtue", resulting in a relative increase in the number of bacteria that cause bad breath, making people around them more susceptible to the sneak attack of odors [4,5].
The same smell, why can others smell it, but the old man himself can't perceive it?
For the sense of smell, an indicator of judgment is the "odor threshold", that is, the minimum concentration at which a certain irritating odor can be perceived by the human body.
The lower the "odor threshold", the more sensitive a person's nose is.
However, studies have found that the "odor threshold" of the elderly is generally 2 to 15 times higher than that of young people [6], indicating that with the increase of age, the human body's olfactory function will gradually weaken, and the nose's recognition and discrimination of odors will become less and less sensitive.
For the elderly with certain diseases, such as Alzheimer's disease and Parkinson's disease, the loss of smell will be more serious.
Moreover, for humans, the sense of smell is adaptable. Even if a certain odor can be recognized at the beginning, after staying in the environment of this odor for a certain period of time, it will not be sensitive.
1. Take a bath and change your clothes more
If because of age or disease, the secretion of smelly substances on the body can not be avoided, try to take a bath as often as possible (if possible, at least two days need to take a bath), change more clothes (change after bathing, do not wait until there is a clear smell), you can avoid the accumulation of gas molecules on the body and clothes.
It is also more to open windows and ventilate the places where the elderly live, which can not only increase the freshness of the air, but also reduce the accumulation of harmful bacteria in the living environment, which is beneficial to health.
2. Hyperactivity
Life is about movement, and the same is true for the elderly. As long as the physical condition allows, the elderly should carry out appropriate exercise.
This reduces the risk of various chronic diseases, maintains the normal function of the liver and kidneys for a longer period of time, and reduces the body odor caused by the damage of these organ functions.
Older adults are best expected to 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) Don't be a fat person
If you are overweight, many chronic diseases that produce an "old age" flavor, such as diabetes, are at increased risk [7].
To avoid becoming fat, you not only need to exercise the necessary amount (refer to point 2), but also pay attention to a balanced diet and eat less high-calorie foods such as fried.
Finally, the point!
1. "Old age smell" does exist, it may be that the body produces a strange smell such as 2-nonaldehyde, or it may be some metabolic diseases (such as diabetes, chronic kidney disease, etc.), or there are bad habits such as alcoholism and smoking.
2. Want to be a refreshing old man, in addition to paying attention to physical condition, timely medical treatment for diseases, but also to develop good living habits, frequent bathing, more clothes, more exercise, maintain normal weight, are good methods!
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/
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