The surprising foods that may be hurting your bones, according to a nutrition expert

Millions affected and a silent gender gap

Osteoporosis is far from rare: in France alone, over 4 million people are affected, with women over 65 carrying the brunt: nearly 40% suffer from weakened bones. But what should we actually eat—or avoid—to keep our bones happy? Here’s the latest science-backed advice from nutrition expert Raphaël Gruman, a Paris-based registered dietitian.

The essentials: Calcium, phosphorus and the fragile balancing act

“Let’s not forget that calcium is the key mineral for strong bones, as it ensures their mechanical strength and participates in the constant renewal of bone tissue,”

says Raphaël Gruman. Roughly 98% of our body’s calcium reserves are stored right in our bones. Each day, a small amount is tapped for other vital missions—think muscle contraction, blood clotting, and nerve signaling—so it needs to be replenished through your diet.

Phosphorus partners up with calcium to form hydroxyapatite crystals, which lend structure and durability to bones. But for this teamwork to work smoothly, the ratio between calcium and phosphorus needs to remain harmonious—ideally around 1 to 1. Consuming too much phosphorus? That prompts your body to compensate by drawing calcium from your bones, which in turn weakens the skeletal framework. That’s why keeping a balance of calcium (from dairy, mineral waters, vegetables) and phosphorus (from meat, fish, eggs) matters for staying strong and metabolically sound.

The surprising foods and habits that can weaken your bones

• Salt: Too much salt can cause the body to flush out more calcium in urine, reducing the available supply for your bones.
  

  “Without going to the extremes of a strict low-salt diet, people should limit processed foods, deli meats, cheese, and be sparing with the salt shaker,”

  says our expert.

• Alcohol: Overdoing it on alcohol disrupts the formation of osteoblasts (the bone-building cells) and makes mineral loss worse.
• Caffeine: Love coffee a little too much? An excess can boost urinary calcium losses. It’s wise to keep coffee intake to three cups per day or less.
• Anti-nutritional factors: Two naturally occurring compounds can bind to calcium in food and hinder its absorption: phytates and oxalates. Phytates show up in whole grains, legumes, seeds, and nuts; oxalates can be found in spinach, rhubarb, beets, cocoa, black tea, and almonds.

That said, whole grains and those veggies offer valuable fiber, vitamins, minerals, and antioxidants—so it’d be a shame to cut them out altogether.

“These foods shouldn’t be banned, but should be enjoyed as part of a varied diet, making sure they aren’t your only source of fiber or plant foods,”

Gruman adds. If you’re looking to limit their effect on calcium absorption, try not to pair calcium-rich foods with those high in oxalates or phytates at the same meal.

A focus on the best sources: Dairy, vitamin D, and high-calcium water

Dairy and its tasty derivatives remain among the top sources of easily absorbable calcium, making them useful allies in the fight against osteoporosis—provided your overall diet is balanced and rich enough in vitamin D.

“Dairy calcium boasts high bioavailability (about 30–35% gets absorbed), but remember, calcium can’t bind to bones without vitamin D. That’s why it’s so important for everyone to supplement during winter, when we get less sunlight,”

insists Raphaël Gruman.

People at risk of deficiency, such as children, seniors, and post-menopausal women, may need to top up on vitamin D year-round.

“It may be a good idea to opt for milk and dairy products fortified with vitamin D, which are becoming increasingly available,”

he adds.

Some mineral waters also offer particularly interesting calcium content, for those who struggle to get enough from foods. In France, for example, ‘calcium water’ is defined as containing more than 150 mg of calcium per liter. Some brands and their calcium content include: Hépar (550 mg/L), Contrex (460 mg/L), Courmayeur (570 mg/L), Talians (290 mg/L), and Vittel (240 mg/L). While American or UK shelves may feature different brands, always check the label for calcium content.

“Calcium from mineral water is absorbed about as well as from dairy products, especially if the water contains bicarbonate—meaning it’s sparkling. However, the still waters with the most calcium can have over twice the amount of their sparkling counterparts, so they’re at least as valuable,”

Gruman clarifies. In practice, drinking half a liter (about 17 fl oz) of one of these waters a day can cover 25–30% of an adult’s daily calcium needs.

“These calcium-rich waters are especially helpful for people who are lactose intolerant or vegan, and don’t consume—or rarely consume—dairy products,”

he notes.

Bones love a little movement

Don’t forget: bone is living tissue that gets stronger when you put it to good use. Every impact, every bit of muscle tension stimulates bone-building cells (osteoblasts) to produce more ossein, which helps fortify your framework.

Exercises with moderate impact—like brisk walking, dancing, hiking, climbing stairs, or energetic gym classes—are especially beneficial, even more so than low-impact joints-friendly sports like swimming or cycling, which don’t stimulate osteoblasts as much to increase bone density.

Bottom line? Your plate and your sneakers both have a say in the strength of your bones. Make each meal and every step count!