Saturday 10/16/2021 (jkzx.com/healthabc.com) — It has been known for long that animals on a calorie-restricted diet tend to have a longer lifespan. Less publicized is that calorie-restricted diet can reduce fecundity – the reproductive capability.
Lifespan and reproduction exclude each other
We know that both humans and animals that engage too much and too often in reproductive activities tend to have a shorter lifespan. Also, a calorie-restricted diet extends lifespan, but cut fecundity.
Some researchers have theorized that this is caused by the nutrient-re-allocation from the reproductive system to the somatic tissue to support survival. (The theory seems to support the idea that the animals and humans are so designed that individual survival is more valued than their reproduction duties).
In 2009, Linda Partridge and colleagues of Institute of Healthy Ageing, University College London in UK published a study in Nature in 2009 to suggest that amino acids play a role in lifespan and fecundity. The study was conducted with flies Drosophila.
Restriction on protein intake is key to the lifespan extension. Calorie restriction is only part of the story
The researchers discovered that restriction on protein or a full spectrum of amino acids or essential amino acids is needed to support life-span extension. They found calorie restricted diet supplemented with additional fat, carbohydrate, vitamins can still extend lifespan in flies they studied. However, when calorie-restricted diet was supplemented with all amino acids, the diet even though low in calories failed to support lifespan extension.
(This observation is good news for people who want to live longer but find a calorie-restricted diet hard to follow because they have to eat less. It seems that you can eat more calories than a calorie-restricted diet can provide to extend your lifespan as long as intake of protein is restricted. Note that the study was done in flies though. The finding also suggests that a calorie-restricted diet with too much protein may not provide the life-extension benefit.)
Too much essential amino acids can offset the effect of calorie-restricted diet of lifespan extension
The study further discovered that not all amino acids but only the essential amino acids in excessive amounts are needed to cancel the lifespan extension benefit by a calorie-restricted diet. Essential amino acids include histidine, phenylalanine, isoleucine, leucine, lysine, methionine, threonine, tryptophan, and valine.
The amino acids provided by calorie-restricted diet should be minimal but sufficient to support the survival only. Too much of all amino acids or essential amino acids make it impossible to extend lifespan. But they are important for a full fecundity. So protein, amino acids particularly essential amino acids are important for reproduction but detrimental for life-span when ingested in large quantity. Men and women who want children should make sure to have sufficient intake of protein.
Methionine helps fecundity but does not hamper the effect of calorie-restricted diet life-span extension
The researchers’ interest is to see if it is possible for a diet that can both support lifespan extension and reproduction. They found the answer – that a calorie-restricted diet supplemented with only methionine – an essential amino acid, the calorie-restricted diet then does not reduce fecundity.
Calorie-restricted diet can expand life-span, but reduce fecundity.
- Calorie-restricted diet may not provide lifespan extension benefits if it contains too much amino acids, particularly essential amino acids.
- Calorie-restricted diet supplemented with additional methionine can support not only life-span expansion, but also fecundity.
- Excessive amounts of non-essential amino acids do not have impact on either lifespan or fecundity.
So what protein you should eat?
- For children whose bodies are developing, those who want to build some muscle, and those who want to have children, they should eat enough essential amino acids. Proteins with high amounts of essential amino acids include milk protein and egg protein.
- For those who want to live longer and do not care much about their re-productivity, then plant-derived proteins are good choice. Plant-based foods have relatively lower amounts of protein or their proteins are not easy to absorb. For example, soy protein has lower levels of essential amino acids who are not good for body building or for those who plan to prime their reproduction capacity. (Dr. Lu)
Source: Grandison, R., Piper, M. & Partridge, L. Amino-acid imbalance explains extension of lifespan by dietary restriction in Drosophila. Nature 462, 1061–1064 (2009). https://doi.org/10.1038/nature08619
2021 年 10 月 16 日星期六 (jkzx.com/healthabc.com) — 眾所周知，限制卡路里飲食的動物往往壽命更長。較少宣傳的是熱量限制飲食會降低生育能力 – 生殖能力。
2009 年，英國倫敦大學學院健康老齡化研究所的琳達·帕特里奇 (Linda Partridge) 及其同事於 2009 年在《自然》雜誌上發表了一項研究，表明氨基酸在壽命和繁殖力中發揮作用。該研究是用果蠅進行的。
- 對於身體正在發育的孩子，想要增肌的成年人，想要生孩子的成年人，都應該攝入足夠的必需氨基酸。 含有大量必需氨基酸的蛋白質包括牛奶蛋白和雞蛋蛋白。
- 對於那些想活得更久並且不太在意自己的生殖能力的人來說，植物來源的蛋白質是不錯的選擇。 植物性食物的蛋白質含量相對較低，或者它們的蛋白質不易吸收。 例如，大豆蛋白的必需氨基酸含量較低，不利於健身或計劃增強生殖能力的人。 (陸博士)
資料來源：Grandison, R.、Piper, M. 和 Partridge, L。氨基酸失衡解釋了果蠅通過飲食限制延長壽命。自然 462, 1061–1064 (2009)。 https://doi.org/10.1038/nature08619