- Reducing caloric intake by 30% for 20 years slowed down indicators of brain aging in a new study of rhesus monkeys.
- Specifically, calorie reduction appeared to enhance the integrity of the brain’s glial cells and neuronal connectivity.
- Such a radical reduction in calories in humans is probably not advisable. However, the study does suggest that calorie reduction may play a role in maintaining human brain function optimally for longer.
A significant, long-term reduction in calorie consumption resulted in a slowing of aging in the brain, according to a study of rhesus monkeys recently published in
Monkeys who consumed 30% fewer calories for 20 years exhibited reduced levels of metabolic dysfunction and oxidative damage in their brains upon being examined post-mortem, after dying naturally.
The authors of the study found less age-related dysfunction in glial cells, which helped calorie-restricted monkeys maintain myelin sheath integrity that is important for neuronal connectivity. The result was that their white matter remained better-preserved than the study’s control group.
The study began in the 1980s and involved two groups of rhesus monkeys. There were 24 male and female monkeys in total, ages between 22 and 37 years, with a median age of 32.1 years.
This is the rough equivalent of 66 to 108 human years. Rhesus monkeys may live up to their late 30s in a laboratory setting — their life span in the wild averages about 19 years.
The control group was fed a normal balanced diet, while the calorie-restricted group received a similar diet, though with 30% fewer calories.
First author, Ana Vitantonio, is a PhD student at Boston University. Vitantonio described what is new in this study:
“The key novelty of this study is that it provides evidence that the neuroprotective effects of caloric restriction observed in short-lived species like rodents — typically on calorie restriction for about two years — also extends to a long-lived species, highlighting conserved mechanisms, rather than prescribing a specific diet for humans.”
She mentioned a clinical trial, CALERIE, “that is currently assessing biomarkers of aging in humans on calorie reduction.”
“The purpose of our study,” said Vitantonio, “is not to suggest that humans should drastically reduce their food intake, but rather to describe the neurobiological basis of aging in oligodendrocytes and microglia and how metabolic interventions like caloric restriction can influence these processes.”
As Michelle Routhenstein, MS, RD, CDCES, CDN, Preventive Cardiology Dietitian at Entirely Nourished, not involved in this study, noted, “eating 30% fewer calories for decades is very difficult to maintain and can lead to muscle loss, nutrient deficiencies, fatigue, and other health risks in humans.”
She also commented that: “Humans are not monkeys, and what works in lab monkeys does not translate directly to people. Monkeys in the study showed benefits from long term, severe calorie restriction, but humans have different metabolisms, activity levels, and nutritional needs.”
“Personalized, sustainable changes can provide many of the same benefits without the downsides of extreme restriction,” said Routhenstein.
She, too, cited the CALERIE study, saying that it suggests far smaller reductions in caloric intake, “of about 12% to 25% can improve blood sugar control, inflammation, cholesterol, and overall metabolic health.”
Vitantonio added that “brain aging is also shaped by many other factors like genetics, physical activity, sleep, etc.”
“Although the brain contains a heterogeneous mix of neurons and glia,” explained Vitantonio, “neuroscience research has historically focused on neurons, viewing glia as mostly supportive. Recently, with advances in high-resolution technologies like single-cell/single nuclei sequencing, it has become clear that glia play active roles in a variety of brain functions, including processes like plasticity, learning, and aging.”
“Microglia,” she said, “are the brain’s resident immune cells, surveilling the environment, clearing debris, and pruning brain cell connections.”
However, as they age, they can become chronically activated and become pro-inflammatory, thus impairing their protective functions.
Helping keep the brain’s connectivity intact are oligodendrocytes, which produce the myelin sheath that enables fast electrical conductivity and provides metabolic support to axons.
However, said Vitantonio, “during aging, oligodendrocytes accumulate cellular damage and lose myelination capacity, which can lead to reduced signal transmission and neuronal vulnerability.”
Worse, since “microglia and oligodendrocytes, as well as neurons and other glial cell types, all belong within an interconnected network, damage within one cell type will influence the system in a ‘domino-like effect,’” Vitantonio said.
Vitantionio noted that calorie restriction “appears to combat age-associated dysfunction in these cells, which may protect against their functional decline. Calorie-restricted oligodendrocytes, for example, show significantly less oxidative, mitochondrial DNA damage from inter/intracellular free radicals.”
The study also observed less inflammation in microglia, “suggesting that caloric restriction helps maintain a more homeostatic, less reactive immune state in the aging brain.”
Acknowledging that calorie restriction might have a beneficial effect on brain aging, Routhenstein nonetheless cautioned, “extreme restriction is not necessary.”
“A more practical approach is a modest and sustainable reduction of about 10–20%, combined with nutrient-dense foods and regular activity,” she said.
In addition, Routhenstein asserted, “It’s important to remember that calorie restriction is not ‘one-size-fits-all.’ How someone responds depends on their starting body weight and the quality of their diet. What you eat during calorie restriction matters as much as how much you eat.”
“Human studies,” she noted, “show that combining calorie reduction with proper nutrition improves insulin sensitivity, inflammation, and blood pressure. Cutting calories without focusing on diet quality reduces these benefits and increases risk.”