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July 10, 2026

Brazil Nuts Could Save Your Thyroid — And 20 Squats Might Save Your Bones

Science Reveals Hidden Nutrient Power and Bone-Protecting Moves for Older Adults

Brazil Nuts Could Save Your Thyroid — And 20 Squats Might Save Your Bones
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From the editor

Every day, Fit Body Science analyzes new fitness and nutrition research — checking the evidence, scoring the claims, and separating what's backed by science from what's not. Here's what we found today.

New research shows selenium and vitamin D supplementation dramatically improve thyroid control in Graves’ disease, while resistance training nearly eliminates bone loss during weight loss in older adults. Meanwhile, Brazil nuts prove as effective as supplements for boosting selenium — but overconsumption risks toxicity.
01
Study

Brazil Nuts vs. Selenium Pills: The Surprising Equivalence

A groundbreaking randomized trial found that consuming Brazil nut butter daily was just as effective as taking a selenium supplement at raising selenium levels in both vegans and omnivores with suboptimal baseline status. This is huge for plant-based eaters who often struggle to meet selenium needs — one or two Brazil nuts per day can deliver the recommended 55 mcg, thanks to their extreme concentration of this trace mineral. But here’s the catch: each nut contains 68–91 mcg, meaning eating more than three daily could push you into toxic territory. Selenium toxicity isn’t immediate, but chronic excess — exceeding the body’s selenoprotein turnover rate — can cause hair loss, GI distress, and nerve damage. The takeaway? Brazil nuts are a natural, delicious solution… but treat them like medicine, not snacks.

You don’t need a supplement to fix low selenium — just 1–2 Brazil nuts a day, no more.

You don’t need a supplement to fix low selenium — just 1–2 Brazil nuts a day, no more.
Key finding
Study Review

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Brazil Nuts vs. Selenium Pills: The Surprising Equivalence

You don’t need a supplement to fix low selenium — just 1–2 Brazil nuts a day, no more.

70/10 evidence
Read the full study review
02
Study

Selenium + Vitamin D: The Secret Weapon Against Graves’ Disease

For those newly diagnosed with Graves’ disease — an autoimmune condition causing hyperthyroidism — standard treatment with methimazole may not be enough. A high-scoring study found that adding 100 mcg/day of selenium and 7,000 IU/week of vitamin D to standard care significantly improved early thyroid hormone control, reducing free thyroxine (FT4) by an extra 12.2 pg/ml at six months. Even more compelling: patients reported better quality of life, especially in cognitive clarity and social functioning, independent of hormone normalization. This suggests micronutrient repletion doesn’t just support the drug — it heals the body’s response to it. If you or someone you know has Graves’, ask your doctor about testing selenium and vitamin D levels. Correction isn’t optional; it’s foundational.

Adding selenium and vitamin D to methimazole therapy cuts thyroid hormone levels further and boosts mental well-being — even before hormones fully normalize.

Adding selenium and vitamin D to methimazole therapy cuts thyroid hormone levels further and boosts mental well-being — even before hormones fully normalize.
Key finding
Study Review

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Selenium + Vitamin D: The Secret Weapon Against Graves’ Disease

Adding selenium and vitamin D to methimazole therapy cuts thyroid hormone levels further and boosts mental well-being — even before hormones fully normalize.

78/10 evidence
Read the full study review
03
Study

Why 20 Squats a Day Might Be Your Best Bone Insurance

Losing weight is great — but for adults over 65, it can silently erode bone density, increasing fracture risk. A rigorous trial found that during a 10% weight loss regimen, those who did resistance training (like squats, lunges, or weightlifting) lost only 0.7% hip bone mineral density (BMD), compared to 2.6% in those who only did aerobic exercise. Combined aerobic and resistance training cut loss to 1.1%. The reason? Mechanical loading from muscle contractions directly stimulates osteoblasts — the cells that build bone. Twenty squats a day isn’t just a TikTok trend; it’s a clinically proven shield against age-related bone loss. You don’t need heavy weights — bodyweight resistance is enough if done consistently.

Resistance exercise reduces hip bone loss by 70–80% during weight loss in older adults — 20 squats a day is a simple, powerful defense.

Resistance exercise reduces hip bone loss by 70–80% during weight loss in older adults — 20 squats a day is a simple, powerful defense.
Key finding
Study Review

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Why 20 Squats a Day Might Be Your Best Bone Insurance

Resistance exercise reduces hip bone loss by 70–80% during weight loss in older adults — 20 squats a day is a simple, powerful defense.

70/10 evidence
Read the full study review
04
Video

The Hidden Danger of Brazil Nuts (Yes, It’s Real)

While Brazil nuts are a nutritional powerhouse, their extreme selenium content makes them a double-edged sword. Chronic intake above 400 mcg/day — easily reached by eating five or more nuts daily — can trigger selenosis, a condition marked by brittle nails, garlic breath, fatigue, and neurological symptoms. Unlike water-soluble vitamins, selenium accumulates, and the body can’t flush it out fast enough. This isn’t theoretical: case reports link daily Brazil nut overconsumption to hospitalizations. The video’s alarm isn’t fearmongering — it’s biochemistry. Enjoy them as a weekly treat, not a daily habit. One or two nuts, three times a week, is the sweet spot.

Selenium toxicity from Brazil nuts is real — and it builds silently over weeks, not days.

Selenium toxicity from Brazil nuts is real — and it builds silently over weeks, not days.
Key finding
The Hidden Danger of Brazil Nuts (Yes, It’s Real)
Video Analysis

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The Hidden Danger of Brazil Nuts (Yes, It’s Real)

Thomas DeLauerWatch
47 supporting3 opposing
05
Video

What 20 Squats a Day Actually Does to Your Body

The claim that 20 squats daily delivers nine benefits isn’t just catchy — it’s grounded in biomechanics. Beyond bone protection, consistent squatting improves hip mobility, glute activation, core stability, and insulin sensitivity. For older adults, it’s a low-barrier, high-reward movement that combats sarcopenia and improves balance. No equipment needed. No gym membership required. Just gravity, bodyweight, and consistency. While the video doesn’t cite studies, the physiological mechanisms are well-established: muscle contraction drives metabolic and structural adaptation. If you’re sedentary, start here. If you’re fit, use squats as a daily reset.

Twenty squats a day is a minimal-effort, maximal-impact habit that supports metabolism, mobility, and muscle retention.

Twenty squats a day is a minimal-effort, maximal-impact habit that supports metabolism, mobility, and muscle retention.
Key finding
What 20 Squats a Day Actually Does to Your Body
Video Analysis

Watch the full analysis

What 20 Squats a Day Actually Does to Your Body

Leonid Kim MDWatch
46 supporting0 opposing

The bottom line

This week’s science reveals a powerful theme: small, precise interventions yield outsized results. Whether it’s two Brazil nuts to fuel your thyroid, 20 squats to protect your bones, or micronutrients to amplify drug therapy — nature and physiology reward consistency over intensity. The key isn’t doing more; it’s doing the right things, with precision and awareness.

Topics

Brazil nuts
selenium
Graves' disease
bone density
resistance training
vitamin D
thyroid health
weight loss and bones
squat routine

Sources & References

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Brazil Nuts & Squats: Thyroid & Bone Science | Fit Body Science