Isabelle Feldhaus

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🩸 Vitamin B6 and anemia: when it helps, when it hurts

Sep 15, 2026

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3 min read

🩸 Vitamin B6 and anemia: when it helps, when it hurts

The one B-vitamin where more can hurt, the rare sideroblastic anemia it treats, and the nerve damage from too much.

🦴 Your Blood Calcium Is Normal. So Why Are You Losing Bone?

Sep 8, 2026

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2 min read

🦴 Your Blood Calcium Is Normal. So Why Are You Losing Bone?

Why a normal blood calcium test misses osteoporosis and whether more calcium actually protects your bones.

🩸 Vitamin B2 and iron: does it actually do anything?

Sep 1, 2026

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3 min read

🩸 Vitamin B2 and iron: does it actually do anything?

How riboflavin affects iron absorption and deficiency and the diets that don't deliver it.

🩸 Can low B12 or folate be why iron isn't fixing your anemia?

Aug 25, 2026

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2 min read

🩸 Can low B12 or folate be why iron isn't fixing your anemia?

You can have textbook-normal iron and still be anemic because a "normal" red-cell size can hide two problems at once.

🥬 Is Spinach Actually a Good Source of Calcium?

Aug 18, 2026

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3 min read

🥬 Is Spinach Actually a Good Source of Calcium?

Oxalate, phytate, and the fortificant in your milk actually decide how much calcium you keep.

Aug 14, 2026

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4 min read

🩸 Does vitamin A help you absorb iron?

It's the most-Googled iron pairing after vitamin C, but "absorb more" and "raise your levels" don't necessarily mean the same thing.

🥛 How Do You Hit 1,200 mg of Calcium a Day — Especially Without Dairy?

Aug 4, 2026

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3 min read

🥛 How Do You Hit 1,200 mg of Calcium a Day — Especially Without Dairy?

The target is reachable from food (even dairy-free), but a few "calcium-rich" foods barely count.

🦠 Is H. pylori why your iron won't come up?

Jul 28, 2026

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3 min read

🦠 Is H. pylori why your iron won't come up?

Months of iron supplements and no change in your ferritin? The reason may be a silent infection in your stomach.

🧃 Does apple cider vinegar actually help your iron?

Jul 21, 2026

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4 min read

🧃 Does apple cider vinegar actually help your iron?

Apple cider vinegar, betaine HCl — the case for boosting your stomach acid runs into one critical problem.

🦴 How Do You Actually Increase Bone Density?

Jul 14, 2026

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4 min read

🦴 How Do You Actually Increase Bone Density?

Ten things claim to build or protect your bones. Here's the ranked order of what the evidence shows can make the biggest difference.

💬 "You don't have low iron, you just can't use it"

Jul 7, 2026

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4 min read

💬 "You don't have low iron, you just can't use it"

Two kinds of low iron feel identical, and lactoferrin only speaks to one of them.

Jun 30, 2026

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3 min read

☀️ Can low vitamin D cause low iron?

Vitamin D lowers hepcidin, the hormone that regulates iron. So does topping it up move the needle?

🌻 Where Does Copper Actually Come From in Your Diet?

Jun 23, 2026

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3 min read

🌻 Where Does Copper Actually Come From in Your Diet?

From nuts to oysters, here's what copper does in your body and the supplement that works against it.

🟠 Is Copper the Reason Your Iron Supplements Aren't Working?

Jun 16, 2026

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3 min read

🟠 Is Copper the Reason Your Iron Supplements Aren't Working?

Copper is everywhere in the iron-deficiency feeds, so we checked whether it actually holds up.

🔬 Science Spotlight #019: Dietary Copper and Human Health

Jun 11, 2026

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2 min read

🔬 Science Spotlight #019: Dietary Copper and Human Health

How much copper do we actually need, where does it come from, and should we worry about getting enough? This review looked at decades of human research and found that the hardest part is measuring copper at all.

Jun 9, 2026

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3 min read

🍬 Gummy Vitamins vs Pills: Do They Absorb the Same?

From vitamin C to iron to melatonin, and the catch that has nothing to do with absorption.

🔬 Science Spotlight #018: Copper Deficiency: A Hidden Cause of Anemia

Jun 5, 2026

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2 min read

🔬 Science Spotlight #018: Copper Deficiency: A Hidden Cause of Anemia

How copper shortage causes anemia and low blood counts and why it's so often mistaken for a B12 problem or bone marrow disorder.

🥱 What Actually Helps After a Bad Night of Sleep?

Jun 2, 2026

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3 min read

🥱 What Actually Helps After a Bad Night of Sleep?

Sleep deprivation affects women differently — and some bad nights aren't like others.

🧬 What Makes Iron So Different in Women and Men?

May 26, 2026

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2 min read

🧬 What Makes Iron So Different in Women and Men?

This mechanism shaping women's iron stores is rarely discussed.

May 19, 2026

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2 min read

🧪 Why "Normal" Iron Often Isn't

The "normal" range on your bloodwork was built on a population that included iron-deficient people.

💊 GLP-1s Help Us Lose Weight. What Else Are They Doing?

May 12, 2026

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2 min read

💊 GLP-1s Help Us Lose Weight. What Else Are They Doing?

The same mechanism that drives weight loss also affects iron, vitamin D, B vitamins, and lean mass, and there are no clinical guidelines yet for monitoring it.

🔬 Science Spotlight #017: The Risk of Nutrient Deficiencies with GLP-1 Weight-Loss Drugs

May 8, 2026

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2 min read

🔬 Science Spotlight #017: The Risk of Nutrient Deficiencies with GLP-1 Weight-Loss Drugs

This review investigated whether people taking popular weight-loss and diabetes drugs (called GLP-1s, like semaglutide) are missing out on important vitamins and minerals.

May 5, 2026

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4 min read

☕ Is Coffee Good or Bad for You?

A new study tracked what happens to gut bacteria when you drink coffee, quit it, and come back.

🔬 Science Spotlight #016: Coffee Consumption and the Microbiota-Gut-Brain Axis

May 5, 2026

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2 min read

🔬 Science Spotlight #016: Coffee Consumption and the Microbiota-Gut-Brain Axis

Demonstrating how coffee acts as a functionary dietary tool via the communication pathway between the gut microbiome and the brain.

🧪 Does Sourdough Deliver Live Probiotics—Or Something Else Entirely?

Apr 28, 2026

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6 min read

🧪 Does Sourdough Deliver Live Probiotics—Or Something Else Entirely?

The oven kills 99.999% of bacteria. Here's what actually drives microbiome shifts.

Isabelle Feldhaus

🩸 Vitamin B6 and anemia: when it helps, when it hurts

🦴 Your Blood Calcium Is Normal. So Why Are You Losing Bone?

🩸 Vitamin B2 and iron: does it actually do anything?

🩸 Can low B12 or folate be why iron isn't fixing your anemia?

🥬 Is Spinach Actually a Good Source of Calcium?

🩸 Does vitamin A help you absorb iron?

🥛 How Do You Hit 1,200 mg of Calcium a Day — Especially Without Dairy?

🦠 Is H. pylori why your iron won't come up?

🧃 Does apple cider vinegar actually help your iron?

🦴 How Do You Actually Increase Bone Density?

💬 "You don't have low iron, you just can't use it"

☀️ Can low vitamin D cause low iron?

🌻 Where Does Copper Actually Come From in Your Diet?

🟠 Is Copper the Reason Your Iron Supplements Aren't Working?

🔬 Science Spotlight #019: Dietary Copper and Human Health

🍬 Gummy Vitamins vs Pills: Do They Absorb the Same?

🔬 Science Spotlight #018: Copper Deficiency: A Hidden Cause of Anemia

🥱 What Actually Helps After a Bad Night of Sleep?

🧬 What Makes Iron So Different in Women and Men?

🧪 Why "Normal" Iron Often Isn't

💊 GLP-1s Help Us Lose Weight. What Else Are They Doing?

🔬 Science Spotlight #017: The Risk of Nutrient Deficiencies with GLP-1 Weight-Loss Drugs

☕ Is Coffee Good or Bad for You?

🔬 Science Spotlight #016: Coffee Consumption and the Microbiota-Gut-Brain Axis

🧪 Does Sourdough Deliver Live Probiotics—Or Something Else Entirely?

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