Many people have this feeling: every time they go to the elderly’s house, they always feel a strange smell. In places with many elderly people, there will also be some taste.
This smell seems to be unique to the elderly. But the old man can’t smell it at all…
It does exist.
Among the various odor molecules emanating from the human body, a substance called 2-nonanal has an unpleasant greasy smell and rotten grass flavor. Studies have shown that this odorant molecule called 2-nonanal can only be detected on the skin surface of people over the age of 40 [1].
2-nonanal 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, and it will also produce more omega-7 unsaturated fatty acids. Much odorous 2-nonanal.
(Source: soogif)
There are also factors from diet, lifestyle, and disease that can lead to increased body odor.
The risk of developing chronic diseases, in particular, increases with age, so it is also associated with “old age”.
Diabetes patients, for example, produce ketone bodies during their metabolism, which are molecules that smell like rotten apples [2].
For example, in patients with chronic kidney disease and renal failure, some metabolites of nitrogen-containing substances in the body cannot be excreted in urine, but are also released through breathing and sweating, causing It releases a carrion-like smell of salted fish [3].
In addition, In patients with oral diseases such as dental caries and periodontitis, the metabolites produced by the overgrowth of bacteria in the oral cavity also emit a foul odor. , which is a common cause of bad breath.
In alcoholics and smokers, the bacteria in the mouth are even more “non-virtuous”, and the bacteria that cause bad breath will increase relatively, making people around More vulnerable to odor attack [4,5].
The same smell, why can others smell it, but the old man can’t perceive it?
For the sense of smell, a judging indicator is the “odor threshold”, which is the lowest concentration of a stimulating odor that can be detected by the human body.
The lower the Odor Threshold, the more sensitive a person’s nose is.
However, studies have found that the “smell threshold” of the elderly is generally 2 to 15 times higher than that of the young[6], indicating that with the increase of age, The olfactory function of the human body will gradually weaken, and the nose will become less and less sensitive to the recognition and discrimination of odors.
The loss of smell is more severe in older adults with certain medical conditions, such as Alzheimer’s disease and Parkinson’s disease.
What’s more, for humans, the sense of smell is adaptive. Even if a certain smell can be recognized at first, after a certain period of time in the environment of this smell, it will not be sensitive.
1. Take a bath and change clothes frequently
If the secretion of odorous substances cannot be avoided due to age or disease, try toTake a bath (if possible, at least once every two days), change clothes (change after bathing, don’t wait until there is a noticeable smell), you can avoid getting on your body and clothes The gas molecules accumulate more and more.
Open more windows to ventilate the place 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 movement, and the same goes for the elderly. As long as the physical condition allows, the elderly should do appropriate exercise.
This reduces the risk of various chronic diseases, maintains normal liver and kidney function for longer, and reduces body odor due to damage to these organs.
It is best for older adults to complete at least 150 minutes of moderate-intensity aerobic physical activity (such as brisk walking, dancing, gardening, etc.) per week, or at least 75 minutes of vigorous-intensity aerobic physical activity per week Activities (such as running, climbing, etc.)[7, 8].
3. Don’t be fat
If you are overweight, you are at increased risk of many chronic diseases (such as diabetes) that have an “old man’s taste” [7].
If you want to avoid becoming obese, you not only need the necessary amount of exercise (refer to point 2), but you also need to pay attention to a balanced diet and eat less high-calorie foods such as frying.
Finally, here’s the highlight!
1. The “old man’s smell” does exist. It may be because of old age, the body produces strange odors such as 2-nonanal, or some metabolic diseases (such as diabetes, chronic kidney disease, etc.) ), or have bad habits such as alcoholism and smoking.
2. If you want to be a refreshing old man, in addition to paying attention to your physical condition and seeing a doctor in time if you have a disease, you must also develop good living habits, such as taking frequent baths, changing clothes, exercising, maintaining A normal weight is a good way to go!
References
[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, TDC, DR Blake, and PR Galassetti, The clinical potential of exhaled breath analysis for diabetes mellitus. Diabetes Research and Clinical Practice, 2012. 97(2): p. 195-205.
[3]Davies, SJ, 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 C 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 and Over. https://www.who.int/dietphysicalactivity/factsheet_olderadults/en/
[8] World Health Organization, What is Moderate and Vigorous Physical Activity? https:https://www.who.int/dietphysicalactivity/physical_activity_intensity/en/
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