What are mTOR and IGF-1, and why are they important for aging?

mTOR and IGF-1 are key growth pathways in the body. While essential for growth and repair, their overactivity is linked to aging and diseases like cancer. Finding a balance is crucial.

How are amino acids, like Leucine, related to mTOR activity and muscle growth?

Leucine is a key sensor for mTORC1 and is crucial for stimulating muscle growth and preventing degradation. The body preferentially directs Leucine to muscles, especially during nutrient deprivation.

What is the speaker's dietary approach to promote longevity?

The approach involves consuming the minimum protein needed for muscle maintenance, lowering carbohydrates until fasting insulin is low (below 3-4 IU), and using fat as a caloric filler. This leads to personalized macro ratios.

How does the speaker view the role of the gut microbiome in aging?

The speaker is cautious, viewing many gut facts as interesting but not necessarily reasons for intervention. While acknowledging significant examples like C. diff reversal, they are not yet convinced of broad clinical applicability for chronic conditions.

What is the connection between ApoE genotype and Alzheimer's disease risk?

Having ApoE4 alleles, particularly ApoE44, significantly increases Alzheimer's risk. However, the speaker emphasizes that phenotype (expressed ApoE levels) may be more predictive than genotype alone.

Is cardiovascular disease preventable through lifestyle?

While cardiovascular disease is the leading killer, its impact has been somewhat blunted by medical advances. Key lifestyle factors like not smoking, managing hypertension, and controlling ApoB/LDL particle number are critical.

What is the speaker's hypothesis on the cause of the rise in Alzheimer's disease?

Given the increasing incidence of Alzheimer's alongside rising longevity, the speaker believes there's an environmental trigger, not just a natural consequence of aging. The strong association with type 2 diabetes and hyperinsulinemia points towards insulin resistance being a key factor.

How is Alzheimer's disease related to diabetes?

Alzheimer's disease is viewed by some neurobiologists as 'brain diabetes.' The primary driver is thought to be neuronal energy problems arising from insulin resistance, making it difficult for neurons to utilize glucose.

What role does lactate play in brain energy metabolism?

Astrocytes in the brain use glucose to produce lactate, which is then shuttled to neurons for energy. This process is thermodynamically favorable and can be particularly important when glucose utilization is impaired.

How might TBI be treated or mitigated using metabolic approaches?

Research is exploring exogenous lactate and BHB to overcome energy deficits in the brain after traumatic brain injury. These can allow glucose sparing and potentially aid in repairing damage.

What is the speaker's perspective on the Warburg effect in cancer?

The speaker doesn't believe the Warburg effect is solely due to defective mitochondria but rather a deliberate optimization by cancer cells for building blocks. Activating mitochondria or using pathways that force mitochondrial activity is a potential therapeutic strategy.

Peter Attia, M.D. on Macronutrient Thresholds for Longevity and Performance, Cancer and More

FoundMyFitness

Education5 min read64 min video

Mar 14, 2016|391,542 views|6,272|490

mTOR RAS pathway Dr. Peter Attia longevity IGF-1 branched-chain amino acids methionine restriction insulin-like growth factor-binding protein 3 sex-hormone binding globulin ketosis cancer p53

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TL;DR

Dr. Peter Attia discusses diet, longevity, cancer, Alzheimer's, and metabolic health, focusing on MTOR, IGF-1, and insulin.

Key Insights

Nutritional strategies for longevity are complex and rely on proxies due to the impossibility of long-term human longevity trials.

MTOR and IGF-1 pathways are crucial for growth but, when overactive, are linked to aging and diseases like cancer.

Leucine is a key amino acid for MTOR activation in muscle, but optimal intake is debated.

Insulin and carbohydrates play a role in IGF-1 signaling, potentially influencing disease risk.

While gut health is important, its direct impact on specific interventions remains an area of active research and skepticism for some.

ApoE4 genotype increases Alzheimer's risk, but lifestyle and phenotype (expressed ApoE levels) may be more critical than genotype alone.

Alzheimer's may be related to neuronal energy deficits and insulin resistance, akin to 'brain diabetes'.

Strategies that promote insulin sensitivity and potentially influence brain energy metabolism, like low-glycemic diets, are considered protective.

Cancer cell metabolism is complex; while some theorize a Warburg effect due to mitochondria optimization for building blocks, others focus on inducing apoptosis via mitochondrial activation.

THE CHALLENGE OF DEFINING OPTIMAL DIET FOR LONGEVITY

Dr. Peter Attia emphasizes that definitively determining the ideal diet for human longevity through long-term randomized clinical trials is practically impossible. Therefore, research relies on proxies, including animal studies and human biomarker analysis. While animal models offer control, extrapolating findings to humans is challenging due to differences in diet and environment. Human studies focus on biomarkers that reflect aging processes, such as MTOR and IGF-1 pathways, acknowledging that definitive certainty remains elusive.

UNDERSTANDING KEY GROWTH PATHWAYS: MTOR AND IGF-1

Two central growth pathways discussed are MTOR (mammalian target of rapamycin) and IGF-1 (insulin-like growth factor 1). While essential for growth and muscle protein synthesis, overactivity of these pathways is linked to aging and diseases like cancer. MTOR is significantly influenced by amino acid intake, particularly leucine, which has a higher affinity for MTOR in muscle. Balancing these pathways is crucial, as both too little and too much activity can be detrimental.

THE ROLE OF AMINO ACIDS, INSULIN, AND CARBOHYDRATES

Leucine is identified as a primary driver of MTOR activation, with its intake during exercise potentially enhancing muscle growth. The relationship between IGF-1, amino acids, and carbohydrates is more complex. While some argue for amino acid exclusivity, evidence suggests carbohydrates, via insulin, also play a role. Insulin's influence on binding proteins, like sex hormone-binding globulin, affects hormone bioavailability, and high intake of refined carbohydrates and sugars is epidemiologically linked to increased cancer risk, suggesting a role in disease amplification.

THE GUT MICROBIOME AND INFLAMMATION

The discussion touches upon the gut microbiome and its connection to immune regulation and inflammation. While acknowledging the fascination with gut bacteria, Dr. Attia expresses skepticism about the direct applicability of current interventions for many chronic conditions, citing a lack of clear causal links and effective tools beyond extreme cases like C. difficile. He distinguishes between observed 'facts' about the gut and actionable 'reasons' for intervention, highlighting the need for more robust evidence.

APOE GENOTYPE, LIFESTYLE, AND ALZHEIMER'S RISK

The conversation delves into the ApoE gene and its association with Alzheimer's disease risk, particularly the ApoE4 allele. However, the emphasis shifts to the phenotype – the actual measured level of ApoE in the body – as potentially more predictive than genotype alone. Lifestyle factors like diet quality, alcohol consumption, and inflammation significantly influence risk, especially for individuals with ApoE4. The research suggests that managing insulin sensitivity and overall brain energy metabolism is critical for mitigating Alzheimer's risk.

ALZHEIMER'S AS NEURONAL ENERGY DEFICIT AND DIABETES OF THE BRAIN

A compelling hypothesis presented is viewing Alzheimer's disease as 'brain diabetes,' characterized by neuronal energy deficits and insulin resistance. This perspective suggests that impaired glucose transport and utilization by neurons, possibly linked to pyruvate dehydrogenase function, drives the disease process. Strategies that enhance insulin sensitivity and facilitate alternative energy pathways, such as using lactate or beta-hydroxybutyrate, are explored as potential protective mechanisms, although clinical validation in non-catastrophic cases is ongoing.

METABOLIC STRATEGIES FOR LONGEVITY AND DISEASE PREVENTION

Dr. Attia outlines a conceptual dietary approach for longevity: consuming the minimum protein needed for muscle maintenance, reducing carbohydrates to the lowest tolerable level (indicated by low fasting insulin and controlled post-meal glucose/insulin response), and using fat as a caloric substitute. This individualized approach aims to optimize metabolic health by managing insulin sensitivity and signaling pathways. The goal is to delay the onset of major age-related diseases like cardiovascular disease, cancer, and neurodegeneration.

CANCER METABOLISM AND THERAPEUTIC OPPORTUNITIES

The discussion touches upon cancer metabolism, specifically the high rate of glycolysis (Warburg effect). While the precise reason – whether mitochondrial dysfunction or optimization for building blocks – is debated, the focus shifts to exploiting these metabolic differences. Strategies that activate mitochondria, such as ketogenic diets or DCA, are hypothesized to be beneficial by generating reactive oxygen species that can push primed cancer cells towards apoptosis. This contrasts with chemotherapy, which also affects normal proliferating cells.

THE COMPLEXITY OF THE BRAIN'S ENERGY SYSTEMS

The brain utilizes lactate produced by astrocytes, which in turn use glucose, as a primary energy source, a process thermodynamically favorable similar to beta-hydroxybutyrate. This lactate shuttle hypothesis is relevant to understanding energy dynamics in conditions like traumatic brain injury (TBI). Research into exogenous lactate or ketone administration following TBI aims to support neuronal energy needs and potentially reduce damage by allowing glucose to be used for crucial repair pathways like the pentose phosphate pathway.

ADVANCES AND UNANSWERED QUESTIONS IN LONGEVITY SCIENCE

The conversation highlights the dynamic nature of scientific understanding, moving from a primary focus on insulin to incorporating gut health, inflammation, and complex genetic interactions like ApoE. While definitive answers remain elusive for many aspects of longevity and disease prevention, the ongoing research into metabolic pathways, genetic predispositions, and lifestyle interventions offers hope for optimizing healthspan and delaying age-related decline.

Mentioned in This Episode

●Supplements

●Software & Apps

●Tools

●Organizations

●Concepts

●People Referenced

Common Questions

Currently, there's no definitive answer, as long-term randomized clinical trials in humans are not feasible. We rely on proxies from animal studies and human biomarker data, acknowledging that definitive proof is elusive.

Mentioned in this video

conceptThe Big Three (causes of death)

The primary diseases that kill most people: cerebrovascular and cardiovascular disease, cancer, and neurodegenerative diseases. Delaying their onset is key to longevity.

conceptEndotoxin

Released from the gut, it's considered a major source of inflammation in the body and can be a marker of a compromised gut barrier.

personCraig Thompson

Co-author of a significant 2009 Science paper on cancer metabolism.

softwaremTOR Complex 2 (mTORC2)

The second complex mTOR can form, with different activities in different tissues.

personLuke Hanley

Co-author of a prominent 2009 Science paper on cancer metabolism.

softwareIGF Binding Protein 3 (IGFBP3)

A protein that traffics IGF-1. Its levels increase as insulin levels decrease and it has a relationship with insulin.

conceptHyperinsulinemia

Elevated insulin levels, strongly associated with Alzheimer's disease, suggesting a link through insulin resistance.

drugDichloroacetate (DCA)

A compound that activates the pyruvate dehydrogenase complex, potentially killing cancer cells by forcing mitochondria to work and generate reactive species.

personMatthew Vanderhyden

Co-author of a 2009 Science paper on cancer metabolism that influenced the speaker's viewpoint on the Warburg effect.

conceptIGF pathway

Another major growth pathway in the body, linked to aging and potentially cancer. It's influenced by amino acids and carbohydrates, and interacts with mTOR.

personJustin and Erica Sonnenburg

Researchers at Stanford whose work on fiber, gut bacteria, short-chain fatty acids, and immune regulation is considered interesting.

personSteven Rosenberg

Mentioned as a researcher Peter Attia worked with in Surgical Oncology.

personMark Shanaga

A colleague at Children's Hospital in Oakland doing brilliant gut research, influencing the speaker's interest in gut health.

softwaremTOR Complex 1 (mTORC1)

One of the two complexes mTOR can form, crucial for protein synthesis and muscle growth, but its overactivity is linked to aging.

drugFecal Microbiota Transplant (FMT)

A treatment that can reverse C. difficile colitis.

conceptApoE44

A genotype of ApoE associated with a significantly higher risk of Alzheimer's disease.