Chapter 8: Eating for Stronger Bones

8

Here's something the supplement aisle doesn't want you to know: the most important thing you can do for your bones nutritionally isn't buying calcium pills. It's eating enough food in the first place.

The Real Priority List

Forget what you've heard about calcium being king. Here's what actually matters, in order:

1. Eating enough (this is #1!)
2. Getting enough protein
3. Vitamin D
4. Calcium
5. Everything else

Most people focus on the bottom of this list while ignoring the foundation. Let's flip that.

Priority #1: Eating Enough

Your bone cells are alive and need energy to work. When you don't eat enough:

• Your body goes into conservation mode
• Bone building gets deprioritized (survival first!)
• Hormones drop (which tanks bone health further)
• No amount of calcium can fix this

The Biggest Bone Nutrition Mistake

Chronic undereating destroys bones. This affects:

• Athletes training hard without eating enough
• People on aggressive diets
• Those with eating disorders
• Elderly people who've lost their appetite

You cannot supplement your way out of not eating enough food.

How much is "enough"? It depends on your activity level. A rough guide for active people:

If you exercise and weigh 60 kg (132 lbs), you might need 2,000-2,500+ calories daily. Cutting to 1,200 calories while training? Your bones will suffer.

Priority #2: Protein

Remember, bones are 35% collagen—a protein. Without dietary protein:

• No raw material to build bone framework
• Important growth signals drop
• Bone formation slows even with adequate calcium

How much protein?

Person	Protein Goal
Average adult	0.8 g per kg body weight (minimum)
For bone health	1.0-1.2 g per kg (better)
Athletes	1.2-2.0 g per kg
Older adults	1.0-1.2 g per kg (they need more, not less!)

Good sources: Meat, fish, eggs, dairy, legumes + grains, soy, Greek yogurt

Pro tip: Spread protein across meals (20-30g each) rather than loading up at dinner only.

What About Collagen Supplements?

Since bones are 35% collagen, you might wonder: can you just take collagen supplements?

Here's what happens when you swallow collagen: your digestive system breaks it down into individual amino acids (glycine, proline, hydroxyproline). These amino acids then enter your bloodstream and your body uses them to build whatever proteins it needs—which may or may not be collagen in your bones.

Some manufacturers claim their "bioactive collagen peptides" can be absorbed intact from the gut and go directly to bone tissue. Studies supporting this claim do exist, but here's the catch: most are funded by the companies selling these products. Independent verification is limited.

My Honest Take

I tried collagen supplements myself and saw no change in my P1NP (a bone formation marker) or BMD. I'm a single data point, not a clinical trial—but it matched my skepticism.

The bottom line: If you have money to spare and want to try them, go ahead. But collagen supplements do not replace a balanced, protein-rich diet. Your body is perfectly capable of making its own collagen if you provide adequate protein from any source, plus vitamin C (needed for collagen synthesis).

Priority #3: Vitamin D

Vitamin D is the calcium helper. Without enough:

• You only absorb 10-15% of the calcium you eat
• With good vitamin D: you absorb 30-40%

That's a HUGE difference. You could be eating plenty of calcium and still not getting the benefit.

Vitamin D: A Hormone in Disguise

Here's something that surprises most people: the active form of vitamin D isn't really a vitamin at all—it's a hormone. And like other hormones, it works by binding to receptors on cells throughout your body, including your bone-building osteoblasts.

The Two Forms of Vitamin D

When doctors measure your vitamin D level, they're measuring the inactive storage form called 25-hydroxyvitamin D (or calcidiol). This is what floats around in your blood and gets reported on your lab results.

But this form can't actually do anything yet. Your body must convert it to the active hormonal form called 1,25-dihydroxyvitamin D (or calcitriol) before it can work.

The Two-Step Activation Process

Step	Where	What Happens
1	Liver	Vitamin D3 (cholecalciferol) → 25-hydroxyvitamin D (inactive, stored in blood)
2	Kidneys	25-hydroxyvitamin D → 1,25-dihydroxyvitamin D (active hormone)

The second step—in the kidneys—is tightly controlled by parathyroid hormone (PTH). When calcium levels drop, PTH rises and stimulates the kidney enzyme (1-alpha-hydroxylase) to produce more active vitamin D.

Why This Matters

• Blood tests measure the inactive form because it reflects your vitamin D stores
• The active form has a short half-life (about 15 hours vs. 15 days for the inactive form)
• Kidney disease can impair activation, which is why people with kidney problems may need the pre-activated form (calcitriol) as medication
• PTH controls the conversion, which is why PTH and vitamin D are so interconnected

Vitamin D Receptors on Bone Cells

Once activated, calcitriol works by binding to vitamin D receptors (VDR) found on osteoblasts—your bone-building cells. When the hormone docks with these receptors, it enters the cell nucleus and turns on genes involved in bone mineralization and calcium handling.

This is why vitamin D is essential for bone health: it's not just helping you absorb calcium from food—it's also directly signaling your bone cells to build properly.

Where does vitamin D come from?

Source	Reality Check
Sunlight	Great, but most people don't get enough (office jobs, sunscreen, winter, northern latitudes)
Fatty fish	Good source, but few people eat enough
Fortified milk	~100 IU per cup—you'd need a lot
Supplements	Often necessary for most people

Target blood level: 30-70 ng/mL (ask for a "25-OH vitamin D" test)

If you're low:

• Loading phase: Higher doses for 8-12 weeks
• Maintenance: Typically 1,000-2,000 IU daily
• Take with food containing fat (it's fat-soluble!)
• Recheck blood levels after 3 months

Priority #4: Calcium (Yes, Only #4)

Calcium matters—but it's not magic, and more isn't better.

The big myth: "More calcium = stronger bones"

The reality: Your bone cells control how much calcium gets deposited. If you're already getting enough calcium (which most people eating dairy or fortified foods are), extra won't help. And it might cause problems.

How much do you actually need?

Age	Daily Goal
Teens	1,300 mg
Adults 19-50	1,000 mg
Women 51+, Men 71+	1,200 mg
Upper limit	2,000-2,500 mg (don't exceed)

Food sources are better than pills:

Food	Calcium
Milk (1 cup)	~300 mg
Yogurt (1 cup)	300-400 mg
Cheese (1 oz)	~200 mg
Sardines with bones	~325 mg
Fortified plant milk	~300 mg
Kale (1 cup cooked)	~180 mg

The Calcium Supplement Controversy

Some studies suggest high-dose calcium SUPPLEMENTS (not food) might increase heart risks. The jury is still out, but the smart approach:

• Get most calcium from food
• Only supplement to fill gaps
• Don't exceed 500 mg per dose (absorption drops with larger amounts)
• Calcium carbonate: take with food
• Calcium citrate: can take anytime

Other Helpful Nutrients

Vitamin K

Helps activate bone proteins and may help direct calcium to bones (instead of arteries).

Good sources: Leafy greens (K1), fermented foods like natto (K2), cheese

Magnesium

Part of bone crystals, involved in vitamin D metabolism. Many people don't get enough.

Good sources: Nuts, seeds, whole grains, leafy greens

What Hurts Bones

Too Much Alcohol

• More than 3 drinks/day is clearly harmful
• Toxic to bone-building cells
• Messes with hormones
• Increases fall risk

Very High Sodium

Makes you pee out more calcium. Moderate your salt intake if your calcium is borderline.

Excessive Caffeine

Slightly increases calcium loss. 2-3 cups of coffee is fine. Don't go overboard.

The Big Picture: Eating Patterns

Instead of obsessing over single nutrients, think about your overall eating pattern:

Good for bones:

• Mediterranean-style diet
• Plenty of vegetables and fruits
• Lean protein at every meal
• Dairy or fortified alternatives
• Healthy fats

Bad for bones:

• Highly processed foods
• Very low calorie intake
• Skipping meals regularly
• Excessive alcohol
• Very low protein

Quick Reference: Daily Targets

Nutrient	Target	Priority
Calories	Enough for your activity level	#1
Protein	1.0-1.2 g per kg body weight	#1
Vitamin D	Blood level 30-70 ng/mL	High
Calcium	1,000-1,200 mg (food first)	Moderate
Vitamin K	Eat your vegetables	Helpful
Magnesium	300-400 mg	Helpful

The Bottom Line

Bone nutrition isn't about calcium supplements—it's about eating enough food, getting adequate protein, and ensuring vitamin D is optimized.

Key takeaways:

• Eating enough calories is #1—you can't supplement your way past undereating
• Protein provides the framework for bone; aim for every meal
• Vitamin D is critical for calcium absorption; most people need supplements
• Calcium is important but overhyped; food sources beat pills
• Excess calcium supplements may have risks
• Focus on overall eating patterns, not single nutrients
• Older adults often underconsume both calories and protein

Next up: the medications available when lifestyle isn't enough—how they work and when to use them.