This Week at Peak Human: What the Egg Carton Actually Tells You About Nutrition

A note from Dr. Goel

A carton labelled "pasture-raised" can cost two to three times one that isn't, and most of us assume we're paying for a meaningfully better egg. This week we published a full evidence review on that assumption, and the honest answer surprised even me: the housing label is a weak predictor of an egg's nutrition — what the hen eats is the strong one. I also want to walk you through two evidence pages we rebuilt this week, on thyroid optimization and PEMF therapy, plus three new articles on fluoride, adult lead exposure, and food-tracking apps. Here's what's new at Peak Human this week.

— Dr. Sanjeev Goel

This week's deep dive: Free-range vs. pasture-raised eggs — which ones are worth paying for?

Egg cartons have become one of the most confidently marketed shelves in the grocery store, and one of the least regulated. Before the nutrition, it's worth knowing what the words are actually allowed to mean.

What the labels actually mean

In the U.S., "pasture-raised" has no federal definition at all — eggs fall under the FDA, which has no standard for the term. The only version with teeth is a third-party seal: Certified Humane's pasture-raised standard requires 108 square feet of living pasture per hen and at least six hours outdoors a day, versus 2 square feet for its free-range tier. In Canada the trap is different: "free run" means the hens are loose indoors; only "free range" means outdoor access. Read the certifier seal, not the adjective.

What the research shows

The cleanest test (North Carolina State University): one flock of 500 hens, identical feed, and the only difference was access to the range. Range eggs had 0.17% omega-3 versus 0.14% — and no difference in vitamin A, vitamin E, or cholesterol (163 vs. 165 mg per 50 g). Which laboratory ran the assay changed the measured value of every nutrient except cholesterol.

Where the big numbers come from (Michigan State, Foods, 2022): pasture eggs carried three to four times the omega-3 of commercial cage-free eggs (1.5–1.74% vs. 0.47%), with an omega-6:omega-3 ratio of 5.7–10.8 vs. 50.6 — but those hens were also on a different feed. The diet, not the field, did most of the work.

Vitamin D is the one thing sunlight genuinely changes: a German randomized hen trial found real outdoor exposure raised yolk vitamin D3 three- to fourfold (14.3 vs. 3.8 µg/100 g dry matter). Yet supermarket free-range eggs bought at random were not notably higher — a door in the barn wall is not sunlight.

"Omega-3 enriched" is the only label with a number behind it: roughly 80–150 mg of DHA per egg versus about 20 mg in an ordinary egg, and algae-fed hens deposit about three times the DHA of flax-fed hens (179 vs. 67 mg per yolk, University of Manitoba).

The honest caveats

Even a genuine threefold rise in vitamin D moves one egg from about 6% to about 18% of the daily requirement — meaningful, but not a strategy. Enriched eggs modestly lower triglycerides in small trials, yet in the largest one (153 adults eating 10 eggs a week) DHA-enriched eggs didn't beat ordinary eggs and raised LDL more. And the counter-intuitive implication: an indoor hen on a flax- or algae-supplemented ration will out-perform an outdoor hen on corn and soy for omega-3 content. Hen welfare, land use, and stocking density are legitimate reasons to pay more. Nutrition, on its own, is a weaker one.

My take: Buy the welfare standard if welfare is your reason — that's a good reason. But don't pay the premium expecting a different nutrient panel; the carton tells you about housing, not nutrition. If your actual goal is more omega-3 or vitamin D, the egg aisle is the wrong lever: an enriched egg delivers a fraction of what a serving of oily fish or a standard supplement does. Knowing where your intake really lands is the whole point of tracking it.

Every egg is still a good egg — complete protein, about 44 IU of vitamin D, and no meaningful cholesterol difference by housing type. Our free nutrition tracker sets your targets from your own lab results so you can see whether any of this moves your numbers.

New on peakhuman.ai this week

Thyroid Optimization — evidence page rebuilt

We rebuilt this page around a different question: not "is it normal?" but "where within normal is risk lowest?" A Thyroid Studies Collaboration analysis of 134,346 adults across 26 cohorts (Lancet Diabetes & Endocrinology, 2023) found a J-shaped curve — free T4 in the 20th–40th percentile and TSH in the 60th–80th percentile carried the lowest cardiovascular and mortality risk, while the highest free T4 band tracked with 34% higher all-cause mortality and 57% higher cardiovascular mortality. The other half of the update is restraint: a 2026 review of 4,892 older adults (BMC Geriatrics) found no quality-of-life or cardiovascular benefit from levothyroxine for mild subclinical hypothyroidism. These are population associations, not individual targets — those belong in a conversation with your physician.

PEMF Therapy — evidence page updated

Pulsed electromagnetic field therapy has a real but narrow evidence base, and the page now says so plainly. A 2026 meta-analysis of 9 randomized trials (457 patients) in knee osteoarthritis (Medicina) found time-dependent effects: WOMAC pain improved significantly at 18–21 days, and stiffness and daily-activity function at one month — but VAS pain and total WOMAC did not reach significance, and the overall risk of bias was high. PEMF's firmest footing remains its FDA-cleared use for stimulating bone healing in nonunion fractures. It is contraindicated with pacemakers or implanted electronics and in pregnancy.

Is Fluoride Safe? Toothpaste, Water and the Honest Evidence

Fluoride toothpaste's evidence for cavity prevention is genuinely strong, with benefit that plateaus above 1,500 ppm. Water fluoridation is the harder conversation: a 2025 meta-analysis of 74 international studies found an inverse relationship between fluoride exposure and children's IQ, though the authors were explicit that the data don't settle whether the low U.S. fluoridation target of 0.7 ppm carries that risk.

Lead Poisoning in Adults

A blood lead level near 100 µg/dL is roughly thirty times the population reference value most labs use. We review where an adult dose that high actually comes from, what lead does to the body at that level, and why the only large randomized chelation trial moved blood lead levels without moving the outcome that mattered most.

Do Food Tracking Apps Actually Work?

Downloading a calorie app doesn't do anything by itself — but a Cambridge analysis pooling 12 randomized trials in 1,190 adults found people who tracked food and exercise digitally lost 2.87 kg (6.3 lb) more than non-trackers, and near-daily logging isn't required to get there.

Also updated: Therapeutic Plasma Exchange

The TPE evidence page now carries the randomized AMBAR trial (347 patients with mild-to-moderate Alzheimer's) and 2025 real-world cognitive data — alongside the important caveat that plasmapheresis without albumin replacement did not rejuvenate epigenetic clocks in a separate 2025 trial. TPE for cognition or longevity remains investigational and is a physician-supervised procedure, not a wellness treatment.

Longevity news worth your minute

Chelation can move the number without moving the outcome. In the largest randomized pediatric chelation trial (780 children, succimer vs. placebo), treated kids' blood lead fell about 4.5 µg/dL more than placebo in the first six months — but IQ at 36 months was no better than placebo (NEJM, 2001).

The fluoride-IQ meta-analysis making headlines has real limits. It pooled 74 studies and found the inverse association held even in the highest-quality subset — but the authors flagged high risk of bias and said the review wasn't designed to answer whether U.S.-level water fluoridation is unsafe (JAMA Pediatrics, 2025).

⚕️ Important disclaimer

This newsletter is for educational purposes only and is not medical advice. Compounds discussed may be investigational and not FDA-approved. Nothing here is a recommendation to start, stop, or change any treatment. Peptide and metabolic therapies carry real risks and should only be used under qualified medical supervision. Always consult your physician before making health decisions.