How human smell shapes friendship, fear and hormones

Humans are far more olfactory than they admit: after a handshake people sniff their own hands, and invisible body odor can predict friendship, spread fear and cut men's free testosterone by about 14% within 20 to 30 minutes.

  • What to do: Treat smell as a real social channel. Notice the hand-to-face sniffing that follows handshakes and give some weight to first impressions that "just click", because odor similarity predicted how friendly strangers rated each other.
  • Why it matters: About 7 million receptors of roughly 350 types feed the olfactory bulb, which connects directly to the amygdala and hypothalamus, so odor can shift arousal, aggression and hormones without conscious awareness.
  • How to apply it: Read "pheromone" claims with caution and use the term chemosignals instead. Remember that baby odor (hexadecanal) lowered aggression in men but raised it in women, so the same signal does not act the same way in everyone.
  • Metrics: 14% drop in free testosterone after sniffing tears; 15 of 16 people identified digitized violets; a perceptual map of 4,000 molecules.
  • Tools: Electronic nose with metal oxide sensors, the Taylor Aggression Paradigm and fMRI.
  • Risks: Smell digitization is at the "1956 black and white TV" stage; rose and anise recreations failed, so do not expect products from it soon.
  • Exceptions: Odor similarity predicted friendship ratings but not performance in the mirror game, and the tear effect was shown for men sniffing women's tears.

Best dental products 2026: toothbrush, floss and toothpaste

A registered dental hygienist names four 2026 favorites they use and recommend to patients: the Quip Rev oscillating toothbrush, GUM Professional Clean floss picks, Sensodyne Clinical Repair toothpaste and the Quip rechargeable cordless water flosser.

  • What to do: Choose an affordable oscillating toothbrush, durable floss picks that do not fray and a sensitivity toothpaste with enamel remineralization, then add a water flosser if you want extra cleaning.
  • Why it matters: Technique decides results. Guide an electric brush slowly from tooth to tooth and never scrub, and floss by hugging the tooth up and down on each side.
  • How to apply it: Subscribe to brush head refills every 3 months, keep floss picks in your bag, car and desk, and start the water flosser on its gentle mode before moving to deep clean pressure.
  • Tools: Quip Rev, GUM Professional Clean Floss Picks, Sensodyne Clinical Repair and the Quip water flosser.
  • Risks: The Sensodyne version they use contains SLS, which can irritate some mouths. Check the label for an SLS-free option if you have irritation.
  • Exceptions: Sensodyne costs more than some pastes, and the water flosser category is crowded, so compare options if budget matters.

Bone density vs fracture risk: what to do after 50

Bone mineral density predicts only about 70% of fracture risk because a two-dimensional DEXA misses bone shape, and lifting challenging loads can thicken the femoral neck cortex even when hip density barely changes.

  • What to do: Do two strength sessions a week built on a squat, hinge, push, pull and carry, add balance moves and keep up daily activity such as walking, dancing or shoveling.
  • Why it matters: Bone mass peaks in your 20s and about 5% of the skeleton is remodeled every year, so the goal after 65 is to hold on to bone and prevent falls.
  • How to apply it: Use 8 to 12 repetitions, pick difficulty rather than maximum weight, try walking lunges and step-ups, and add a few sets of 10 to 12 small hops if your joints allow.
  • Metrics: BMD explains about 70% of fracture risk, FRAX estimates 10 year fracture probability, and CTX and P1NP track bone resorption and formation.
  • Tools: DEXA with 3D hip analysis, FRAX, a machine circuit for beginners, Function Health tests, Prolon and Momentous creatine appear in the episode.
  • Risks: Calling an X-ray bone on bone can scare people away from exercise, and heavy loads with poor form raise injury risk for beginners.
  • Exceptions: For someone using a walker with severe arthritis, the goal is function and fall prevention, not bone density.

Brain scans and blood tests that reveal brain health

Brain scans of people who were overweight or obese looked about 8 years older, and low estrogen, testosterone or thyroid hormone also sped up brain aging, so fixing metabolism, hormones and nutrition can visibly restore brain structure.

  • What to do: Treat the brain through the body. Track cardiometabolic health, hormones and nutrients, and add a brain MRI with quantitative analysis plus Alzheimer's blood markers when family history or age 50 to 60 makes them relevant.
  • Why it matters: Brain changes can show up about 30 years before Alzheimer's, and around 60% of people diagnosed with dementia have cardiometabolic problems. Scans show recovery after nutrition is restored, as in anorexia, where the brain improved most.
  • How to apply it: Get a broad blood panel that includes vitamin D, iron, omega 3, heavy metals, insulin, thyroid, sex hormones, homocysteine and methylmalonic acid, then retest after changes to see your trend.
  • Metrics: Alzheimer's incidence doubles every 5 years after age 70, from about 5% at 70 to 10% at 75 and 20% at 80. One APOE4 copy roughly triples risk, and two copies (about 6% of people) raise it 9 to 10 times. Key markers include p tau 217, amyloid beta 42/40, neurofilament light and GFAP.
  • Tools: Functional MRI, PET, NeuroQuant brain age and brain charts, plus the Function Health panel. Sponsors named in the episode: Bon Charge red light mask, Paleovalley bars, Timeline Mitopure, Seed DS 01, BiOptimizers magnesium and Fatty15.
  • Risks: A single marker or a normal structural MRI can miss the problem, because many psychiatric conditions show up in function, not structure. Imaging is more controversial than blood work.
  • Exceptions: Only about 2% of Alzheimer's cases are directly genetic. APOE4 tilts risk but is not destiny, and its effect varies by ancestry.

Fasting and Akkermansia: how fasting affects gut lining

Fasting feeds Akkermansia, a gut bacterium that eats the intestinal mucus layer, and with no fiber or polyphenols competing for its attention it can overgrow and thin that lining, which fits a Swedish study of about 4,200 people linking high Akkermansia on a low fiber diet to higher type 2 diabetes odds.

  • What to do: Stay in the Goldilocks zone. Pair fasting with polyphenol and resistant starch foods such as berries, apple peel and crucifers, and vary your foods instead of repeating the same ones every day.
  • Why it matters: Biology follows a U shaped curve, so even a good thing like fasting can drift out of balance over time through accumulation, degradation, attenuation and compensation. Akkermansia is good in balance and harmful when it has only the gut lining to eat.
  • How to apply it: Eat foraging style foods the day before a fast (berries, resistant starch, crucifers, lower protein), keep fasts shorter, and treat a small handful of berries during a fast as acceptable. Do not take probiotics daily as a rule. Consider a few weeks only after antibiotics.
  • Metrics: About 20 types of mucin are produced in the body. Apple peel carries very long procyanidin chains of roughly 30,000 units. Count calories weekly if at all, not daily.
  • Tools: Element 500 mg sodium cans, with 100 mg potassium and 30 mg magnesium, no sugar and no caffeine, sipped through a fast. A CGM and ketone monitor can show how small foods affect you.
  • Risks: Repeated long fasts can trigger hyperphagia, a binge urge that grows with a big meal. Daily antioxidants may blunt useful signaling after exercise, and carnivore style diets can raise Akkermansia without fiber to balance it.
  • Exceptions: Akkermansia works best when your levels are low. Older adults tend to have more Akkermansia but fewer Bifidobacteria, which can strain the immune system.

What happens if you never floss: from plaque to gum disease

Plaque biofilm that your toothbrush cannot reach hardens into tartar, and that step turns bleeding gums into periodontal disease, an infection that can destroy the bone holding your teeth in place.

  • What to do: Clean between your teeth every day with floss, floss picks, interdental brushes or a water flosser. The method matters less than doing it.
  • Why it matters: Gum disease is linked with heart disease, diabetes and chronic kidney disease. Diabetes and gum disease affect each other in both directions, so poor gums can make blood sugar harder to control.
  • How to apply it: If you have not flossed consistently, start today, because there is always a point in starting. If your gums bleed, keep cleaning gently. Bleeding is usually a sign they need more consistent cleaning, not less.
  • Metrics: The progression runs from plaque to gingivitis (red, swollen, tender, bleeding gums) to tartar, then to periodontal disease and, in advanced cases, tooth loss.
  • Tools: String floss, floss picks, interdental brushes and water flossers all disrupt the biofilm between teeth.
  • Risks: Tartar is hardened plaque attached to the tooth, and neither brushing nor flossing removes it. Only a dental professional can.
  • Exceptions: Persistent bleeding can have other causes, so talk to your dental provider. If you have not had a professional cleaning in a while, book one, then restart your routine.

10 tips to stay strong, active and healthy after age 50

An average American spends about 12.5 of their final years sick, disabled or in a nursing home, and this video blames chronic inflammation and chronic disease rather than age, which ten habits can push back.

  • What to do: Pick one to three of the ten habits and start tonight: get labs, eat fat and animal protein first, cut sugar, grains and seed oils, lift something heavy two or three times a week and sleep at least 7 hours.
  • Why it matters: Visceral fat is the most dangerous fat, and in a British Medical Journal study the weakest grip carried about one and two thirds the risk of death of the strongest grip.
  • How to apply it: Measure your waist and height with a tape, take private photos every one to three months, fast 12 to 14 hours before blood tests, skip snacks, stand up and sit down every 10 to 15 minutes and raise the head of your bed.
  • Metrics: Hemoglobin A1C, fasting insulin, triglycerides, HDL, hs-CRP, vitamin D 25, sex hormones, waist-to-height ratio, five timed floor rises and 10 seconds on each leg.
  • Tools: A tailor's tape, light dumbbells, red bricks or 2 by 4 blocks under the bed legs and the Proper Human Diet community for accountability.
  • Risks: Snacks of any kind, seed oils, alcohol and sugary breakfasts keep insulin and inflammation high.
  • Exceptions: Some people do fine on 6.5 hours of sleep, and a first step can be as small as walking to the mailbox.

Normal blood sugar but insulin resistant? How to find out

Yes, you can be insulin resistant with normal blood sugar, because glucose is the last marker to rise while fasting insulin climbs first, and a fasting insulin under 5 is the target almost nobody tests.

  • What to do: Ask for fasting insulin, hemoglobin A1C and fasting glucose, then check your waist to hip ratio and body composition instead of trusting glucose alone.
  • Why it matters: One patient had glucose under 110 after two colas worth of sugar yet an insulin near 300, and doctors who test only glucose miss many cases.
  • How to apply it: Cut starch and sugar, eat protein, fat and 30 grams of fiber, walk 10 to 20 minutes after meals, lift weights, sleep well and fast 12 to 14 hours overnight.
  • Metrics: Fasting glucose 70 to 90, fasting insulin under 5, A1C about 5.0 to 5.2, post meal glucose under 110 to 120, waist to hip ratio under 0.8 for men and 0.9 for women.
  • Tools: Function Health tests with an insulin resistance score from 0 to 100, a continuous glucose monitor for a few weeks and a tape measure.
  • Risks: Statins, sleep apnea, chronic stress and artificial sweeteners can worsen insulin resistance or cravings.
  • Exceptions: A glucose spike after eating is normal, and thin people can still carry hidden fat, so body composition matters more than weight.

A rational guide to supplements for sleep and focus

Supplements work best as the third layer after behavior and nutrition, and the smartest move is to test one single ingredient formula at a time for about a week, because that is how you find the minimum effective dose and drop whatever does nothing for you.

  • What to do: Answer three questions first: how well do you sleep, how good is your nutrition and what is your budget. With about $100 a month or more, start with a broad foundational formula (vitamins, minerals, digestive enzymes, probiotics, prebiotics, adaptogens).
  • Why it matters: No supplement or drug can make up for poor sleep, light exposure, exercise and food for long. Ingredients also behave differently in different people, and the ideal dose for you may even be zero.
  • How to apply it: For sleep, avoid caffeine after 2 p.m. and food in the last 2 hours. To fall asleep faster, try magnesium threonate or apigenin for one week each. For waking at night, consider 900 mg myo inositol. For focus, keep stimulants (caffeine) separate from neuromodulators (alpha GPC 300 to 600 mg, L tyrosine 500 to 1,000 mg).
  • Metrics: Aim for more than 1 g of EPA a day from fish oil. Fadogia agrestis is around 600 mg a day, cycled 8 weeks on and 2 off, or 12 weeks on and 1 month off. Tongkat ali is around 200 to 600 mg a day, with blood work after 8 to 12 weeks. Protein is about 1 g per pound of body weight.
  • Tools: Examine.com for ingredient forms, and a high quality omega 3 as the single most impactful supplement.
  • Risks: Fadogia agrestis can be toxic to testicular cells at high doses, alpha yohimbine can cause strong anxiety, and melatonin doses are far above natural levels and may not keep you asleep.
  • Exceptions: Skip theanine if intense dreams wake you at night. Women should expect some supplements to act differently across the menstrual cycle. Always check with a physician before changing any protocol.

Can diet improve mental health? A doctor's message of hope

A family physician with 22 years of practice says a keto carnivore diet, which they call a proper human diet, can heal down to the mitochondrial level and in many cases put severe mental health disorders into complete remission, based on patient stories rather than trials.

  • What to do: If you live with anxiety, depression or brain fog, talk to your doctor and consider a time-limited trial of a keto carnivore diet built on meat, eggs and animal fat.
  • Why it matters: The physician has seen patients on a handful of medications with side effects such as lost sexual desire, and reports hope returning once they changed how they ate.
  • How to apply it: Eat the meat without buying supplements or products, note your mood, anxiety and mental clarity week by week, and do not change psychiatric medication without professional supervision.
  • Metrics: Stories in the video include Todd, who describes symptoms gone in three weeks, and a person with schizophrenia discharged within a month or two after decades in an institution.
  • Risks: These are testimonies, not controlled studies, so stopping prescribed medication on your own could be harmful.
  • Exceptions: The approach is not only a weight loss diet, and people without a formal diagnosis but with constant fog and fatigue are also part of the picture.