Calcium is not enough: the vitamins that decide where it goes

For decades the advice for strong bones was simple: take calcium. The science of bone has since become more interesting. Calcium is the raw material, but two vitamins act as its managers.

Vitamin D brings calcium in

Without vitamin D, the gut absorbs only a small share of the calcium we eat. Vitamin D made in the skin or taken in food is converted first in the liver and then in the kidneys into calcitriol, its active form. Calcitriol switches on the proteins that carry calcium across the gut wall.

Despite abundant sunshine, low vitamin D is widely reported across India. Indoor lives, covered skin, air pollution and darker skin, which needs longer exposure to make the same amount, all play a part.

Vitamin K2 guides calcium to bone

Once calcium is in the blood, it needs direction. Vitamin K2 activates two proteins that matter here:

• Osteocalcin, which helps bind calcium into the bone matrix.
• Matrix Gla protein, which helps keep calcium out of soft tissues such as the walls of arteries.

Vitamin K2 is found in fermented foods and some animal products. The form called MK-7 stays in the body longer than others.

The rest of the team

Bones are living tissue built on a protein framework, so adequate protein matters. Magnesium is needed to activate vitamin D. Weight-bearing exercise, from brisk walking to climbing stairs, tells bone cells to keep building.

A practical plan

• Include calcium-rich foods every day: milk, curd, paneer, ragi, sesame and leafy greens.
• Get safe sunlight on the arms and legs a few times a week.
• Keep protein adequate at each meal.
• Walk, climb and carry. Bones strengthen when they are loaded.
• After menopause, or after a fracture from a minor fall, ask your doctor about a bone density scan.

Try our calcium estimator in Self-checks to see roughly how much calcium your usual meals provide.