Browse the evidence

In women, short sleep duration (≤5 hours) is associated with significantly higher levels of high-sensitivity C-reactive protein (hs-CRP) compared to 7 hours of sleep, whereas no such association exists in men.

If you are a woman, consistently sleeping 5 hours or less is linked to higher levels of hs-CRP, a marker of inflammation and cardiovascular risk, compared to sleeping 7 hours. This specific inflammatory risk was not observed in men in this study. Prioritizing 7-8 hours of sleep may be particularly important for managing inflammation in women.

In women, sleeping 8 hours is associated with significantly lower Interleukin-6 (IL-6) levels compared to sleeping 7 hours, suggesting an optimal sleep window for this specific inflammatory marker.

For women, extending sleep from 7 to 8 hours may help lower IL-6, a key inflammatory marker. While 7 hours is often cited as standard, this data suggests 8 hours might be the sweet spot for inflammation control in women, whereas men showed no such benefit.

Higher baseline 25(OH)D concentrations result in a significantly smaller increase in serum 25(OH)D following vitamin D supplementation, demonstrating an inverse dose-response relationship.

If you are vitamin D deficient, you will likely see a much larger increase in your blood levels from supplementation than someone who is already sufficient. This is not a failure of the supplement, but a biological response to the saturable nature of liver enzymes. Deficient individuals should expect a robust response, while sufficient individuals may see minimal changes from standard doses.

Higher BMI and body fat percentage significantly reduce the efficacy of vitamin D supplementation, resulting in smaller increases in circulating 25(OH)D concentrations compared to leaner individuals.

If you have a higher BMI, standard vitamin D doses may be less effective because the vitamin gets stored in fat tissue rather than circulating in your blood. You may need higher doses to achieve the same blood levels as a leaner person. This is a known physiological effect, not a lack of effort.

Low handgrip strength is significantly associated with a higher number of chronic diseases and multimorbidity in adults aged 50 and older, independent of chronological age, BMI, and other confounders.

Get your handgrip strength measured as part of a routine health check, especially if you are over 50. Low strength is a strong signal of underlying chronic disease burden, potentially more so than your age alone. While this study is observational, maintaining or improving muscle strength through resistance training is a feasible strategy to potentially reduce the risk of multiple chronic diseases and premature mortality.

High-intensity interval training (HIIT) is relatively safe for patients with coronary artery disease or heart failure when administered within supervised cardiac rehabilitation settings, with a major adverse cardiovascular event rate of 1 per 17,083 training sessions.

If you have stable heart disease or heart failure, high-intensity interval training is likely safe when done in a supervised cardiac rehab program. The risk of a serious heart event is extremely low (about 1 in 17,000 sessions). Do not attempt this unsupervised; ensure your condition is stable and you are monitored by cardiac staff.

Weight loss induced by diet and exercise improves insulin sensitivity in overweight and obese postmenopausal women, an effect mediated by reductions in systemic inflammation (specifically CRP, IL-6, and sTNFR-1) independent of fat mass loss.

For postmenopausal women, combining a modest caloric deficit (250-350 kcal/day) with regular moderate-intensity exercise (3x/week) significantly improves how your body uses insulin. This benefit comes not just from losing weight, but from the reduction in body-wide inflammation, which directly helps insulin work better.

Habitual consumption of spicy foods (specifically chili peppers) is inversely associated with total mortality, with high-frequency consumers (6-7 days/week) showing a 14% relative risk reduction compared to low-frequency consumers (<1 day/week).

If you enjoy spicy foods, eating them frequently (almost daily) is associated with a lower risk of death from all causes, particularly cancer, heart disease, and respiratory diseases. This benefit was observed in a large Chinese population study, suggesting that incorporating chili peppers into your regular diet may support longevity, provided you do not have specific digestive conditions that prevent you from tolerating them.

The mortality benefit of spicy food consumption is significantly stronger in individuals who do not consume alcohol compared to those who do.

If you do not drink alcohol, incorporating spicy foods into your diet may offer even greater longevity benefits than for drinkers. This suggests a potential synergistic health effect or that alcohol might blunt the metabolic benefits of capsaicin.

Health-related claims on food labels significantly increase the likelihood of purchasing and consuming the labeled product compared to identical products without such claims.

If you see a health or nutrition claim on a packaged food, expect that it will make you more likely to buy and eat it than if the package were blank. This is a powerful marketing tool that works in both lab settings and real-world sales data. Use this knowledge to be aware of your own biases when shopping.

A high pre-treatment Prevotella-to-Bacteroides (P/B) ratio predicts significantly greater body fat loss when consuming a high-fiber, whole-grain diet (New Nordic Diet) compared to a standard diet, whereas individuals with a low P/B ratio show no such differential benefit.

If you are trying to lose fat using a high-fiber, whole-grain diet, your gut bacteria composition matters. A simple test of your Prevotella-to-Bacteroides ratio can predict success: if your ratio is high, you are likely to lose significant fat on this diet; if it is low, you may not see benefits over a standard diet, suggesting you might need a different nutritional approach.

Focusing on isolated nutrients for chronic disease prevention is counterproductive and potentially harmful, whereas whole food patterns (food synergy) provide superior health outcomes by leveraging complex, non-random mixtures of constituents.

Stop focusing on isolated nutrient supplements for chronic disease prevention. Instead, prioritize whole food patterns like the Mediterranean or Prudent diets. Look at the food matrix: saturated fat from dairy behaves differently than from meat. If you are not deficient in a specific nutrient (like Vitamin B12 or Folate for neural tube defects), adding isolated supplements may be ineffective or harmful. Focus on eating diverse, whole foods rather than trying to optimize individual chemical compounds.

In obese non-diabetic adults, experiencing transient nausea or vomiting during dose escalation of liraglutide 3.0 mg is associated with significantly greater weight loss compared to those who do not experience these symptoms.

If you are taking liraglutide for weight loss, experiencing nausea or vomiting, especially in the first few weeks, is common and often a sign that the medication is effectively engaging your GLP-1 receptors. This side effect is linked to greater weight loss. It is usually transient and mild. Do not stop the medication abruptly; instead, discuss slower dose escalation with your provider to manage symptoms while maintaining the therapeutic benefit.

Traditional Australian Aboriginal hunter-gatherer diets were characterized by high protein intake, low carbohydrate availability, and high fiber content, resulting in a macronutrient profile distinct from modern Western diets.

Focus on a diet where protein is the dominant macronutrient source, carbohydrates are limited and derived from fibrous plant sources, and fiber intake is high. This mirrors the macronutrient distribution of traditional hunter-gatherer diets rather than modern Western patterns.

Better self-reported sleep quality is associated with better mental health outcomes, specifically showing a U-shaped relationship where both short and long sleep durations correlate with higher depression and anxiety.

Prioritize sleep quality over just duration. If you are sleeping 7-9 hours but still experience high anxiety or depression, your sleep efficiency or continuity may be poor. This study suggests that poor sleep quality is strongly linked to mental health issues, regardless of age. Aim for consistent, efficient sleep rather than just time in bed, and be aware that both sleeping significantly less or significantly more than average can negatively impact mental well-being.

Poor sleep quality is modestly but consistently associated with poorer cognitive performance, particularly verbal phonemic fluency, across the entire adult lifespan (18-98 years).

Maintain good sleep hygiene throughout your life, not just as you age. This study shows that poor sleep quality consistently impacts cognitive performance, especially verbal fluency, from young adulthood to old age. Prioritizing sleep is a key strategy for maintaining cognitive health at any age.

Sodium bicarbonate supplementation (0.2-0.4 g/kg body mass) improves performance in high-intensity sprints lasting ~60 seconds by buffering acid buildup, but causes gastrointestinal distress in many users.

Take 0.2-0.4g of sodium bicarbonate per kg of body weight 60-150 minutes before a ~60 second high-intensity effort. To avoid stomach upset, split the dose, take it with a small carb meal, or use a loading protocol over 2-4 days. Test this in training first, as responses vary widely.

Low levels of physical activity are associated with a significantly higher risk of incident dementia in older adults (aged 60+), specifically demonstrating a threshold effect where the lowest activity quintile faces increased risk compared to higher activity levels.

Maintain a baseline level of physical activity as you age to protect your brain. This study suggests that even modest activity (moving out of the 'lowest quintile' of inactivity) is protective against dementia, with the strongest benefits seen in those over 75. You do not need to be an elite athlete; simply avoiding a sedentary lifestyle and engaging in regular movement helps preserve brain volume and reduces dementia risk.

Higher levels of physical activity are linearly associated with larger total cerebral brain volume and hippocampal volume in older adults, suggesting a structural preservation mechanism.

Regular physical activity helps maintain the physical size of your brain, specifically the hippocampus, which is critical for memory. This structural preservation is observed linearly with activity levels, meaning more activity generally correlates with larger brain volume in older adults.

Shift work involving circadian misalignment and chronic sleep restriction significantly increases the risk of cardiovascular events, metabolic syndrome, and mood disorders.

If you work nights or rotating shifts, recognize that your body's internal clock is fighting against your schedule. This misalignment directly increases your risk for heart disease, diabetes, and mood disorders. Prioritize sleep quality, manage stress, and be aware of your cardiovascular risk factors more closely than day workers.

Timed exposure to bright light during night shifts and melatonin administration can facilitate circadian adaptation and improve sleep quality in shift workers.

To adapt to night shifts, expose yourself to bright light during your shift and in the early morning. After your shift, wear sunglasses to block morning light to help your body adjust. You can also take melatonin (1-2 mg) to help you sleep during the day. Avoid rapidly rotating schedules if possible.

Distributing magnesium intake across multiple small doses throughout the day significantly increases fractional absorption and retention compared to consuming the same total amount in a single bolus.

If you take magnesium supplements, do not take the entire daily dose at once. Split the total amount into 2-4 smaller doses taken throughout the day with meals. This strategy maximizes absorption because the body's active transport mechanisms (TRPM6/7) are more efficient at lower concentrations, whereas high single doses saturate these pathways and lead to lower relative absorption.

High doses of magnesium impair fractional absorption efficiency, whereas low doses are absorbed more efficiently, although absolute absorption increases with dose.

Avoid taking massive single doses of magnesium (e.g., >500mg at once) if your goal is efficient absorption. While you will absorb more total milligrams, the percentage absorbed drops drastically. To maximize efficiency, keep individual doses moderate (e.g., <100-200mg) and spread them out.

Androgenic-anabolic steroid administration significantly lowers serum Lipoprotein(a) [Lp(a)] concentrations, which may have a beneficial effect on cardiovascular risk, although this benefit is offset by the adverse effects on other lipids.

AAS use tends to lower Lipoprotein(a), which is generally considered a good thing for heart health. However, because AAS simultaneously destroys your 'good' cholesterol (HDL) and raises 'bad' markers, you cannot assume the Lp(a) benefit cancels out the damage. The net effect on heart disease risk is likely negative and complex.