An estimated 10 million Americans have osteoporosis — also known as brittle bone disease — which is  caused by a combination of hormonal, genetic, and lifestyle conditions such as lack of estrogen, not doing weight-bearing exercises, and excessive smoking and alcohol consumption. It accounts for some 2 million bone fractures annually.

But that's not all osteoporosis can break. According to a study in the journal Bone Research, osteoporosis is linked to an 80% increase in the risk of dementia.

That’s because there's an intrinsic biological connection between bone and brain health.

Bone and muscle proteins and hormones can cross the blood-brain barrier and promote neuron growth and neurotransmitter production. But if that flow is reduced or blocked (often because of self-damaging lifestyle choices), the communication pathway between bones and brain is reduced, and cognition suffers.

To prevent osteoporosis — and protect your brain — it's essential to get weight-bearing exercise at least twice a week for 20-30 minutes. You can use your own body weight, hand weights, barbells, or weight machines at the gym. Walking (aim for 10,000 steps daily) counts too.

A diet rich in bone-building calcium and vitamin D is also a top priority. Foods loaded with calcium include non- or low-fat dairy; tofu and soy beans; dark, leafy greens such as kale and spinach; and canned salmon, anchovies, and herring.

Vitamin D is found in salmon, sardines, mushrooms, and fortified cereals (sugar-free), as well as plant-based milks.

And ask your doctor if you need to take vitamin D supplements.

For more nutritional advice, check out my book "What to Eat When."