Anti-Aging Expert on How Missing This Vitamin Is As Bad As Smoking, and What You Should Know About Creatine!
In this episode of The Diary Of A CEO, Steven Bartlett and Dr. Rhonda Patrick explore the connection between lifestyle choices and longevity. They discuss how physical inactivity can be as harmful as smoking, while exercise—especially high-intensity interval training—can extend life expectancy and improve brain function. The conversation covers key nutritional factors, with particular attention to vitamin D, magnesium, and omega-3 fatty acids.
Patrick explains the impact of sleep quality on brain health and describes how practices like intermittent fasting and sauna use affect cellular repair and inflammation. The discussion also examines creatine supplementation's effects on cognitive performance, especially during sleep deprivation, and explores how exercise promotes brain health through processes like neurogenesis and the production of beneficial compounds like beta hydroxybutyrate.
This is a preview of the Shortform summary of the Jul 28, 2025 episode of the The Diary Of A CEO with Steven Bartlett
Sign up for Shortform to access the whole episode summary along with additional materials like counterarguments and context.
1-Page Summary
Exercise, Fitness, and Physical Health
Rhonda Patrick and Steven discuss how physical activity profoundly influences health span and longevity. Patrick explains that a sedentary lifestyle, combined with obesity and harmful habits, can reduce life expectancy by up to 14 years. She emphasizes that being sedentary is as harmful as having type 2 diabetes or smoking.
High-intensity interval training (HIIT) shows particular promise, with Patrick noting its ability to reverse brain atrophy and enhance cognitive function through lactate production. She highlights that even moving from low to low-normal cardiorespiratory fitness can add two years to life expectancy, while high fitness levels can extend life by about five years.
Nutritional Interventions and Micronutrients
Patrick discusses several critical nutrients affecting health and longevity. She reports that vitamin D deficiency increases dementia risk by 80%, while supplementation can reduce this risk by 40%. Similarly, she notes that 50% of the U.S. population is magnesium deficient, a concerning statistic given magnesium's vital role in DNA repair and energy production.
Regarding omega-3 fatty acids, Patrick emphasizes their importance by explaining that a low omega-3 index is as detrimental to mortality as smoking. She points out that increasing omega-3 intake, either through supplements or seafood consumption, can add approximately five years to life expectancy.
Lifestyle Factors Like Sleep, Fasting, and Heat Exposure
Sleep quality significantly impacts brain health, with Patrick explaining how poor sleep accelerates the buildup of harmful amyloid beta plaques. She notes that eating earlier in the day can enhance sleep quality, as demonstrated by users of the My Circadian Clock app.
Patrick describes how intermittent fasting can improve metabolism and weight loss beyond simple calorie restriction, while also triggering autophagy—the body's cellular repair process. She also discusses sauna use, explaining how heat exposure mimics exercise benefits, boosting heart health, reducing inflammation, and enhancing brain function.
Cognitive Performance and Brain Aging
Patrick shares exciting findings about creatine supplementation, noting that 20-30 grams can not only counteract cognitive deficits from sleep deprivation but can actually enhance performance beyond well-rested levels. She particularly recommends creatine supplementation for vegans and vegetarians who lack dietary sources.
Regarding brain aging, Patrick emphasizes that exercise, particularly HIIT, promotes neurogenesis and can reverse brain atrophy. She explains how beta hydroxybutyrate serves as an alternative brain energy source, potentially reducing oxidation and inflammation while activating brain-derived neurotrophic factor (BDNF) for improved neural connections.
1-Page Summary
Additional Materials
Clarifications
- High-intensity interval training (HIIT) involves alternating short bursts of intense exercise with brief recovery periods. It is characterized by maximal effort, short rest periods, and anaerobic energy system utilization. HIIT sessions typically last under 30 minutes and can vary in interval durations based on fitness levels. HIIT is known to improve athletic capacity, condition, and glucose metabolism.
- Lactate is a byproduct of glucose metabolism that was traditionally viewed as a waste product. However, recent research suggests that lactate plays a crucial role in brain function, serving as an alternative energy source for neurons. This lactate utilization by the brain can enhance cognitive function, particularly during tasks that require high levels of mental performance. High-intensity interval training (HIIT) has been shown to increase lactate production, which may contribute to the cognitive benefits associated with this form of exercise.
- The omega-3 index is a measure of the amount of omega-3 fatty acids, specifically EPA and DHA, in red blood cell membranes. A higher omega-3 index is associated with reduced risk of cardiovascular disease and mortality. Increasing omega-3 intake through supplements or diet can improve the omega-3 index and potentially extend life expectancy. Low omega-3 index levels have been linked to increased mortality risk, similar to the risks associated with smoking.
- Autophagy is a natural process where cells break down and recycle damaged or dysfunctional components within themselves. It helps maintain cellular health by removing unnecessary or harmful substances, promoting cell survival and adaptation to stress. Autophagy plays a crucial role in various physiological functions, including immunity, aging, and the prevention of diseases like cancer and neurodegenerative disorders. This process is tightly regulated and can be influenced by factors like nutrient availability, exercise, and certain medications.
- Beta hydroxybutyrate is a type of ketone body produced by the liver during periods of fasting or low carbohydrate intake. It can serve as an alternative fuel source for the brain when glucose availability is limited, crossing the blood-brain barrier to provide energy for brain cells. This process is part of the metabolic state known as ketosis, where the body shifts from using glucose to using ketones for energy production. Beta hydroxybutyrate has been linked to various potential benefits, including improved cognitive function, reduced inflammation, and enhanced brain health.
- Brain-derived neurotrophic factor (BDNF) is a protein crucial for the growth, development, and maintenance of neurons in the brain. It plays a significant role in promoting neuroplasticity, which is the brain's ability to adapt and form new connections between neurons. BDNF is essential for learning, memory, and overall cognitive function, as it supports the survival of existing neurons and encourages the growth and differentiation of new neurons. Higher levels of BDNF are associated with improved brain health, enhanced mood, and better cognitive performance.
Counterarguments
- While sedentary lifestyles are linked to reduced life expectancy, genetics and other environmental factors also play significant roles, and not everyone who leads a sedentary lifestyle will experience such drastic reductions in life span.
- The comparison of sedentariness to type 2 diabetes or smoking may oversimplify the complex and multifactorial nature of these conditions and their impact on health.
- HIIT is beneficial, but it may not be suitable for everyone, especially those with certain health conditions or those who are new to exercise; lower-intensity activities can also provide significant health benefits.
- The claim that moving from low to low-normal cardiorespiratory fitness can add two years to life expectancy may not account for individual variations and other lifestyle factors that contribute to longevity.
- The benefits of vitamin D supplementation in reducing dementia risk are still being researched, and while there is evidence supporting this claim, it may not be as straightforward as the percentages suggest.
- The statistic that 50% of the U.S. population is magnesium deficient may not accurately reflect the complexity of nutrient status assessment and the varying definitions of deficiency.
- While omega-3 fatty acids are important, the comparison to the mortality risk of smoking may not account for the dose-response relationship and other lifestyle factors that contribute to health outcomes.
- The impact of sleep quality on brain health is significant, but other factors such as stress, mental health, and lifestyle choices also play crucial roles in the development of amyloid beta plaques.
- The benefits of intermittent fasting are supported by research, but it may not be the best approach for everyone, and some individuals may experience negative effects or find it unsustainable.
- Sauna use has health benefits, but it is not a replacement for exercise, and individuals with certain health conditions should exercise caution.
- Creatine supplementation may improve cognitive function, but its effects can vary, and long-term safety and efficacy require more research.
- The role of beta hydroxybutyrate as an alternative energy source for the brain is an emerging area of research, and its long-term effects on brain health are not yet fully understood.
Related Shortform Content
Get access to the context and additional materials
Exercise, Fitness, and Physical Health
Rhonda Patrick and Steven delve into the significant impacts of exercise on health, examining how physical activity influences longevity and health span while contrasting sedentary lifestyles with physically active ones.
Exercise Affects Health Span and Longevity
Rhonda Patrick mentions that a sedentary lifestyle, combined with obesity and harmful activities like smoking and drinking, can shorten life expectancy by up to 14 years. She equates sedentarism to diseases like type 2 diabetes and smoking, calling it a disease on its own due to its severe impact on early mortality. Globally, most people are on the sedentary scale, not moving enough, which is a concern given that sedentarism could be considered more lethal than having conditions like type 2 diabetes or cardiovascular disease without engaging in physical activity.
Sedentary Lifestyles Reduce Lifespan By 14 Years, as Harmful as Smoking and Diabetes
The notion that being sedentary could be considered a disease highlights the grave impact inactivity has on longevity when compared to known threats such as diabetes or cardiovascular diseases.
Interval Training Reverses Brain Atrophy, Improves Cognition
Interval training, especially high-intensity interval training (HIIT), has been shown to reverse brain atrophy and improve cognitive functions. Patrick points out that lactate produced during vigorous exercise acts as a signaling molecule to prompt bodily adaptation, leading to the activation of brain-derived neurotrophic factor (BDNF) which facilitates neurogenesis and cognitive enhancement.
Exercise Adds 2 Years to Life Expectancy
Moving from low cardiorespiratory fitness levels to even a low normal level can increase life expectancy by about two years, as stated by Rhonda Patrick.
Cardiorespiratory Fitness Is a Key Predictor of Longevity
Patrick highlights the importance of cardiorespiratory fitness for longevity and details the benefits of high-intensity interval training in improving this aspect of health. She discusses various exercises and HIIT protocols, such as the Norwegian 4x4, describing how this type of workout can effectively enhance the cardiovascular system and push back age-related decline and diseases.
3 Weeks of Bed Rest Impairs Cardiorespiratory Fitness Like 30 Years of Aging
The Dallas Bedrest Study from the 1960s, mentioned by Patrick, dramatically illustrates the effects of inactivity, whereby three weeks of bed rest in college students had a worse impact on their cardiorespiratory fitness than 30 years of aging. This ...
Here’s what you’ll find in our full summary
Exercise, Fitness, and Physical Health
Additional Materials
Clarifications
- Brain-derived neurotrophic factor (BDNF) is a protein that plays a crucial role in promoting the growth, development, and maintenance of neurons in the brain. It is involved in neurogenesis, which is the process of forming new neurons in the brain. BDNF is known to enhance cognitive functions such as learning, memory, and overall brain health. During vigorous exercise, BDNF is released as a response to physical activity, contributing to the improvement of cognitive abilities and potentially protecting against neurodegenerative conditions.
- The Dallas Bedrest Study conducted in the 1960s involved college students undergoing three weeks of bed rest to observe the effects of inactivity on cardiorespiratory fitness. The study found that the decline in cardiorespiratory fitness from three weeks of bed rest was more severe than the decline typically seen in 30 years of aging. This comparison highlights the detrimental impact of inactivity on cardiovascular health and underscores the importance of maintaining an active lifestyle to preserve fitness levels and overall health.
- High-Intensity Interval Training (HIIT) involves alternating between short bursts of intense exercise and brief periods of rest or lower-intensity activity. The Norwegian 4x4 protocol is a specific HIIT method where individuals perform four minutes of high-intensity exercise followed by three minutes of active recovery, repeated four times. This type of training is effective in improving cardiorespiratory fitness by challenging the cardiovascular system and promoting physiological adaptations that enhance overall aerobic cap ...
Counterarguments
- Sedentary lifestyle may not be the sole cause of reduced lifespan; genetic factors and other social determinants of health also play significant roles.
- The comparison of a sedentary lifestyle to diseases like diabetes may oversimplify the complex nature of these conditions and their treatment.
- While most people may be sedentary, cultural, socioeconomic, and environmental factors can influence physical activity levels, and these should be considered when addressing sedentarism.
- The benefits of HIIT may not be suitable for everyone, especially those with certain health conditions or at different stages of life.
- The production of lactate and its role in cognitive enhancement may not be the only mechanism by which exercise improves brain function.
- The increase in life expectancy from improving cardiorespiratory fitness levels may vary widely among individuals due to genetic differences and other lifestyle factors.
- While cardiorespiratory fitness is important, other forms of physical fitness, such as strength and flexibility, also contribute to overall health and longevity.
- The Dallas Bedrest Study's findings, while significant, may not be directly applicable to different populations or age groups.
- The claim that people with high cardiorespiratory fitness live about five years lon ...
Related Shortform Content
Get access to the context and additional materials
Nutritional Interventions and Micronutrients
Rhonda Patrick highlights the severe implications of vitamin D deficiency on dementia risk and overall brain health while emphasizing the critical roles of magnesium and omega-3 fatty acids in health and longevity.
Vitamin D Deficiency Is Severe
Vitamin D Deficiency Boosts Dementia Risk By 80%
Patrick indicates that inadequate vitamin D levels can elevate the risk of dementia by 80%. This deficiency affects not only disease risk but also mood and depression, indicating immediate quality of life impacts alongside long term neurodegenerative risks.
Vitamin D Supplements Reduce Dementia Risk By 40%
According to multiple studies, vitamin D supplementation can decrease the risk of dementia by 40%. Additionally, those with dementia or Alzheimer's who took vitamin D supplements had improved cognition and lower markers of amyloid plaques.
Vitamin D Essential for Brain Health and Longevity
70% of the US population has insufficient vitamin D levels largely due to limited UVB exposure from the sun, which is necessary for the body to produce vitamin D3. This is exacerbated by factors such as sunscreen use, melanin, and geographical latitude. Those with more melanin require significantly more sun exposure to generate the same amount of vitamin D3, posing a greater risk for severe deficiency. Optimal vitamin D levels are linked to the lowest all-cause mortality, and Patrick emphasizes the hormonal role of vitamin D in regulating gene activation and deactivation, which affects over 5% of the human genome.
Magnesium Is a Critical but Often Deficient Micronutrient
50% of Us Population Magnesium Deficient
Patrick notes that half the U.S. population does not achieve adequate magnesium levels. Magnesium is crucial for over 300 enzymatic reactions, DNA repair, and energy production. Magnesium levels have been shown to inversely correlate with all-cause mortality and cancer-related deaths.
Magnesium Deficiency Raises Pancreatic Cancer Risk By 24% per 100Mg Decrease
A 24% increase in the incidence of pancreatic cancer is associated with each 100mg decrease in magnesium intake.
Magnesium Is Vital for DNA Repair, Energy, and Longevity
Magnesium's role is paramount in DNA repair, and a deficiency can lead to prioritizing immediate energy production at the expense of long-term health and prevention of aging-related diseases like cancer. Patrick discusses the triage theory, positing that the body allocate ...
Here’s what you’ll find in our full summary
Nutritional Interventions and Micronutrients
Additional Materials
Clarifications
- Vitamin D deficiency can increase the risk of dementia by 80%. Supplementing with vitamin D can potentially reduce the risk of dementia by 40%.
- Magnesium deficiency has been linked to an increased risk of pancreatic cancer. Research suggests that for every 100mg decrease in magnesium intake, there is a 24% rise in the incidence of pancreatic cancer. This association underscores the importance of maintaining adequate levels of magnesium for overall health and potentially reducing the risk of developing pancreatic cancer.
- The omega-3 index is a measure of the amount of omega-3 fatty acids, particularly EPA and DHA, in red blood cell membranes. A higher omega-3 index is associated with reduced risk of heart disease and overall mortality. Studies suggest that having a low omega-3 index is as harmful for health and longevity as smoking, emphasizing the importance of adequate omega-3 intake for overall well-being.
- The triage theory, proposed by Dr. Bruce Ames, suggests that the body prioritizes nutrients during scarcity, allocating them to essential short-term functions over long-term health maintenance. This theory implies that when nutrients like magnesium are limited, the body ...
Counterarguments
- The correlation between vitamin D deficiency and dementia risk does not necessarily imply causation; other factors may contribute to both conditions.
- The effectiveness of vitamin D supplements may vary among individuals, and some studies have shown conflicting results regarding their impact on dementia risk.
- The claim that 70% of the US population has insufficient vitamin D levels may not account for recent public health initiatives aimed at improving vitamin D intake.
- The association between magnesium deficiency and pancreatic cancer risk may be influenced by confounding variables such as diet and lifestyle factors.
- The triage theory regarding magnesium allocation in the body is a hypothesis that may not fully explain the complex interactions and priorities of nutrient utilization.
- The statement that a low omega-3 index is as deadly as smoking may oversimplify the risks associated with smoking, which includes a wide range of health ...
Get access to the context and additional materials
Lifestyle Factors Like Sleep, Fasting, and Heat Exposure
Experts in the health field, such as Rhonda Patrick and Steven Bartlett, emphasize the critical importance of lifestyle factors like sleep, fasting, and heat exposure on one's overall health and wellbeing. They point out the impacts on everything from brain health to metabolic benefits and stress resilience.
Sleep Is Critical for Brain Health and Longevity
Patrick stresses that good sleep is crucial and serves as a modifier of Alzheimer's disease risk. Amyloid beta plaques, which interfere with memory formation, increase and lead to neuronal death due to poor sleep over long periods. This is because sleep activates the glymphatic system which clears away proteins like amyloid that accumulate during the day.
Sleep Loss Speeds Up Amyloid Beta Plaque Buildup in Brain
Patrick explains that amyloid beta plaques are protein aggregations in the brain that should be cleared routinely but can disrupt synaptic connections and contribute to Alzheimer's disease if they build up due to inadequate sleep.
Enhancing Sleep and Brain Function By Eating Earlier
Bartlett mentions that 23% of people reported better sleep after intermittent fasting in nine human trials, though causation is tricky to prove. Patrick adds that eating within an earlier time window and ceasing to eat three hours before bedtime lead to improved sleep, as late-night eating interferes with sleep quality. Users of the My Circadian Clock app reported enhanced sleep when they stopped eating earlier.
Fasting and Time-Restricted Eating Have Metabolic Benefits
Patrick discusses the various benefits fasting can confer, such as enhancement of glucose levels, blood pressure, and weight loss, which can occur beyond calorie restriction alone.
Intermittent Fasting Enhances Glucose, Blood Pressure, and Weight Loss Beyond Calorie Restriction
Research has shown that intermittent fasting can lead to better metabolism and weight loss beyond just reducing caloric intake. For example, even if two groups consume the same calories, the fasting group can see better improvements. Patrick notes that it's important for those fasting to ensure they get enough protein and engage in resistance training to avoid muscle loss.
Fasting Triggers Autophagy, Repairing Damaged Cell Components
Autophagy, the body's way of cleaning out damaged cell components, occurs most during a fasted state, which could be around 12 hours of fasting. Resistance training and exercise in conjunction with fasting may enhance this process. The length of fasting required to activate autophagy specifically is not yet clear, but Patrick suggests a 16-hour fasting window could achieve this effect.
Heat Exposure From Saunas Has Wide-Ranging Benefits
Patrick shares that heat exposure through sauna use has broad health benefits, inclu ...
Here’s what you’ll find in our full summary
Lifestyle Factors Like Sleep, Fasting, and Heat Exposure
Additional Materials
Clarifications
- The glymphatic system is a waste clearance system in the brain that helps remove toxins and waste products, including amyloid beta, during sleep. It works by flushing cerebrospinal fluid through the brain tissue, facilitating the removal of metabolic waste and proteins that can be harmful if they accumulate. This process is crucial for maintaining brain health and function, as the buildup of substances like amyloid beta can contribute to neurodegenerative diseases like Alzheimer's. Activation of the glymphatic system primarily occurs during sleep, emphasizing the importance of quality rest for brain detoxification and overall cognitive well-being.
- Autophagy is a natural process where cells remove and recycle damaged or dysfunctional components within themselves. It helps maintain cellular health by breaking down and clearing out unnecessary or faulty structures like proteins and organelles. This self-cleaning mechanism plays a crucial role in cellular maintenance, renewal, and overall function. Autophagy is triggered in response to various conditions like nutrient deprivation, stress, or fasting, allowing cells to adapt and survive by removing harmful elements.
- Sauna-induced physiological responses emulating exercise means that when you expose your body to heat in a sauna, it can lead to similar changes in your body as if you were engaging in physical exercise. This includes increased heart rate, improved circulation, and sweating, which are all responses that also occur during exercise. Sauna use can mimic some of the cardiovascular benefits of exercise, such a ...
Counterarguments
- While sleep is important for brain health, some research suggests that genetic factors may play a more significant role in Alzheimer's disease risk than lifestyle factors.
- The relationship between amyloid beta plaque buildup and Alzheimer's is complex, and some studies have found that plaque buildup can occur even with adequate sleep.
- The benefits of eating earlier and intermittent fasting on sleep and brain function may not be universal, as individual responses to dietary changes can vary widely.
- Fasting may have metabolic benefits, but it is not suitable for everyone, and some individuals, such as those with certain medical conditions or pregnant women, should avoid it.
- The exact timing and benefits of autophagy related to fasting are still not fully understood, and more research is needed to establish clear guidelines.
- Sauna use may have health benefits, but it can also pose risks for individuals with certain health ...
Related Shortform Content
Get access to the context and additional materials
Cognitive Performance and Brain Aging
As we age, we face various challenges in maintaining cognitive health. Rhonda Patrick sheds light on how creatine supplementation can aid cognitive function, and how certain lifestyle factors can significantly impact the aging of our brains.
Creatine Supplementation Can Improve Cognitive Function
Creatine Negates Sleep Deprivation's Cognitive Deficits and Enhances Performance Beyond Well-Rested Levels
Rhonda Patrick shares excitement about creatine's potential in cognitive function, especially under stress, such as lack of sleep. When someone is sleep-deprived for 21 hours and given 20-30 grams of creatine, not only does it negate the cognitive deficits from sleep deprivation, but it also enhances cognitive performance beyond well-rested levels. She also notes that she personally ups her creatine intake to 20 grams on high-demand cognitive days, emphasizing that creatine helps the brain regenerate energy more quickly.
Creatine Benefits Vegans and Vegetarians Lacking Dietary Sources
Rhonda Patrick stresses the significance of creatine for vegans and vegetarians who do not have sources of creatine in their diet. She explains that lifestyle factors, especially exercise, affect the aging process significantly. Her vegan friends, upon supplementing with creatine, have reported improved energy levels and needing less sleep.
Lifestyle Factors Can Significantly Impact Brain Aging
Rhonda Patrick insists that factors such as exercise and sleep are major determinants of cognitive and physical capabilities with age, more so than genetics. She highlights the impact of vitamin D on aging brains and its link to increased brain damage when in low levels.
Exercise Reverses Brain Atrophy and Promotes Neurogenesis
Intense exercises, like high-intensity interval training, result in the production of lactate, which benefits brain health by triggering the growth of new neurons (neurogenesis) and improving neuroplasticity. This ties into how exercise can reverse brain atrophy and promote brain health. Studies have shown that after a year of exercise, there's growth in the hippocampus—the part of the brain involved in learning and memory—indicating the growth of new neurons and overturning of brain atrophy normally expected with aging.
Rhonda Patrick ...
Here’s what you’ll find in our full summary
Cognitive Performance and Brain Aging
Additional Materials
Clarifications
- Creatine supplementation can enhance cognitive function, particularly in situations of stress like sleep deprivation. It has been shown to not only offset cognitive deficits caused by lack of sleep but also improve cognitive performance beyond well-rested levels. Creatine is beneficial for individuals who do not consume it through their diet, such as vegans and vegetarians, and can lead to improved energy levels and reduced need for sleep.
- Regular exercise and sufficient sleep play crucial roles in maintaining cognitive health as we age. Exercise, particularly high-intensity workouts, can stimulate the growth of new neurons and improve brain plasticity, potentially reversing brain atrophy. Adequate sleep is essential for cognitive function and overall brain health, as it allows the brain to rest, repair, and consolidate memories. Lifestyle factors like exercise and sleep can have a significant impact on brain aging, potentially outweighing genetic influences.
- Beta hydroxybutyrate is a type of ketone body produced by the liver during periods of fasting or low carbohydrate intake. It serves as an alternative fuel source for the brain when glucose availability is limited. Beta hydroxybutyrate can cross the blood-brain barrier and be converted into acetyl-CoA, which enters the citric acid cycle to generate energy for brain cells. This process is particularly beneficial duri ...
Counterarguments
- Creatine supplementation may not be universally effective for all individuals, and its long-term effects on cognitive function are not fully understood.
- The claim that creatine can enhance cognitive performance beyond well-rested levels may be an overstatement, as the evidence might not be conclusive or may only apply to specific cognitive tasks or populations.
- While creatine may benefit those with no dietary sources, it is important to consider the potential for over-supplementation and the need for a balanced diet.
- Genetics still play a significant role in brain aging, and while lifestyle factors are important, they do not completely overshadow the influence of genetics.
- The extent to which exercise can reverse brain atrophy and promote neurogenesis may vary greatly among individuals, and other factors such as stress and environment also play critical roles.
- The benefits of Beta hydroxybutyrate and its comparison to glucose as an energy source for the brain require more research to fully under ...
Get access to the context and additional materials
Create Summaries for anything on the web
Download the Shortform Chrome extension for your browser
