- During aging, important metabolic pathways become more and more dysregulated.
- These pathways regulate how our cells respond to nutrition.
- Examples of these pathways are receptors in the cells that gauge amino acid and carbohydrate levels, or that measure intracellular energy levels.
- The more these nutrient sensing pathways are activated by nutrients like amino acids or glucose, the faster we age.
- This is because an overabundance of nutrients shifts cells into the “lazy” modus, so that they repair and mainstem themselves less well, which accelerates aging.
- On the other hand, a scarcity of nutrients, as happens during fasting or by reducing nutrient intake, puts cells into a maintenance and repair modus, which slows down aging.
- The western diet with an overabundance of fast sugars, animal proteins and unhealthy fats leads to an overactivation of these nutrient-sensing pathways, and accelerates aging.
- Specific natural substances can inhibit these nutrient-sensing pathways, enabling the cells to repair, maintain, and protect themselves better.
HOW METABOLIC DYSREGULATION AND AN OVERABUNDANCE OF FOOD CONTRIBUTES TO AGING
Nutrient sensing plays an important role in the health of our cells. Our cells contain many receptors and systems to sense how many nutrients are present. These are nutrients like glucose, amino acids, but also substances that are increased in our body when many nutrients are available, like insulin (increases after a carbohydrate rich meal), insulin-like growth factor, ATP, NADH and so on.
“Nutrient sensing pathways” that play an important role in aging. These pathways are in fact sensors that our cells use to sense the amount of nutrients present in the body.
Two well-known nutrient sensing pathways are the mTOR and IGF-1 pathway.
mTOr is a receptor that is primarily activated by amino acids. The more protein you eat, the more mTOR is activated, given protein is broken down in your gut into individual amino acids, which enter the blood circulation and will stimulate mTOR in our cells.
Other examples of nutrient sensors are the insulin receptor and the insulin-like growth factor 1 (IGF-1) receptor, which are primarily activated by insulin (insulin increases in response to an increase of glucose in the blood).
So if you eat a large steak in the evening, the proteins in the steak are broken down into amino acids, which end up in our blood and activate mTOR. If you eat lots of sugars and starches, then lots of glucose will circulate in the blood, triggering a large insulin peak, which activates insulin and IGF receptors.
The Aging Process
The more these receptors are activated, the faster we age.
If cells sense there are plenty of nutrients, they will maintain themselves less well. After all, there are more than enough nutrients to build new cellular parts, so there is no need to repair and maintain everything. This reduced repair and maintenance leads cells to decline and age faster.
The opposite is also true. If there are few nutrients, the cells will protect themselves better, ramping up cellular repair enzymes, recycling pathways, and protective enzymes, to sit out the period when few nutrients are available. This in fact protects the cells against aging.
This mechanism explains why fasting or substantially reducing calorie intake (“caloric restriction”) can extend lifespan. Less nutrient sensing pathways are stimulated leading to better maintenance and repair, resulting in life extension.
Other important nutrient sensing pathways are the sirtuin-NAD and AMPK pathways, which mainly detect how much energy (NAD and AMP) is present in the cell. If there is less energy, which is mostly the consequence of less food being available, these pathways are activated, leading to improved cellular maintenance and the slowing down of the aging process.
The older we get, the more dysregulated these nutrient sensing pathways become. Some of these pathways become less sensitive to nutrients (which contributes to insulin resistance for example), while others get stuck in the “on” position too much of the time. This leads to those cells maintaining themselves less well, becoming more damaged, and aging faster.