Weekly Focus: Diet and Aging
What I learned this week
This week’s learnings are all about how we age. If you’re interested in the latest research on this topic and are into all the nitty gritty scientific details, I would highly recommend grabbing a copy of the book How Not to Age by Dr. Michael Greger.
Theories of Aging
Rate of Living Theory
We’re starting with what is probably my least favorite model of aging. The rate of living theory says that the more metabolically active a person is, the more tissue turnover they will experience in the same period of time as someone less metabolically active. Increased cellular turnover is the cause of aging. Subscribers to this theory suggest that a fast-paced, active lifestyle is associated with a shortened life when compared to a slower, gentler life.
Molecular Clock Theory
In the molecular clock theory, telomeres are considered important markers of aging. The more a cell divides, the shorter the telomere becomes, and, eventually, a person’s telomeres become so small that cell division becomes impossible. Unable to generate new tissues, aging begins as the remaining cells lose function over time. I feel that if this theory were true, then “shortened telomeres” would be a cause of death. We know that our cells turnover about every three months (except for neurons), so wouldn’t a person who reached the end of their telomeres only have about that much time left? The logic here feels poorly supported, in my opinion.
Free Radical / Oxidative Stress Theory
Probably the most accurate explanation of the aging process and the increased susceptibility for chronic disease is the oxidative stress theory. Oxidative stress is caused by exposure to reactive oxygen species. This happens when we inhale smoke, consume environmental pollutants, and are exposed to the radiation from the sun, but reactive oxygen species are also generated naturally during cellular metabolism. The idea is that the more exposures we have to these highly reactive molecules, in the absence of antioxidants, the more damage they can do to our cell walls and DNA. This adequately explains why the risk of cancer increases with age and with those who tan frequently or smoke.
Read more about vitamins and their roles as antioxidants here!
Hayflick’s Theory of Limited Cell Regeneration
Leonard Hayflick made massive scientific contributions to our study of cellular biology and co-founded the National Institute of Aging. His research on cells in vitro suggest that human cells are pre-programmed to a limited number of total divisions. His estimations suggest that in the absence of disease, our cells would only ever be able to replicate about 60 times, giving us a max lifespan of about 120 years. Of course, this is difficult if not impossible to test outside of a lab, since most humans are not even making it close to 100 before dying of other causes.
More Theories on Aging
The Cross-Linking Theory
The Evolutionary Senescence Theory
The Neuroendocrine Hypothesis
Read about these theories in this pdf from the American Federation for Aging Research.
Diet and Aging
Caloric Restriction
We’ve made some truly interesting discoveries in the realm of diet and lifespan. Most notably, restricting calorie intake by up to 40% can predictably increase the lifespan of a variety of lab animals.
Intermittent Fasting
Intermittent fasting is one method of achieving a caloric restriction. Proponents of intermittent fasting also suggest the fasting window maximizes our body’s ability to identify and neutralize free radicals. In this line of thought, IF extends life by way of the oxidative stress theory.
Blue Zones
The Blue Zones are five pockets of the world with the longest living citizens. They were initially identified by Dan Buettner, a national geographic photographer and author of the Blue Zones Diet. Buettner has spent years trying to understand exactly what these people are doing differently, and he sums it up into 9 lifestyle pillars. 3 of the 9 pillars directly relate to diet.
1. Mostly Plants
People in all five of the blue zones consume a mostly plant-based diet; meats are infrequently eaten (maybe once a week), and typically only on special occasions. Maybe, then, we should be flipping the script: instead of aiming for meatless mondays, mondays would be the single day of the week where meat is consumed.
2. The 80% Rule
this principle is another dietary takeaway – in Japan, the saying is “hara hichu bu,” meaning that you should eat until you are 80% full. This could be an important mindset for regulating weight over time. This rule aligns quite well with the caloric restriction research mentioned above.
3. Wine
the trend in four out of five of the blue zones is to enjoy no more than 1-2 glasses per day, in a social setting!
