What you eat can have a big influence on your bone health. Foods rich in calcium and vitamin D are both major factors in maintaining strong bones. But it's not only about the food. Physical activity and estrogen levels are also important parts of this equation.

Let's start with how much calcium our bodies need every day. Most adults up to age 50 need about 1000 mg daily. Adults over 50 need at least 1200 mg to as much as 1500 mg every day.

Vitamin D is a fat soluble vitamin best known for its role in bone health. Bone cells are continually breaking down and reforming, and without enough vitamin D, bones can become thin and brittle.

There are few foods that actually contain vitamin D.... Some fish and fish oils are naturally rich in vitamin d, and almost all of the milk supplied in the united states is fortified with vitamin D, as well as some cereals, juices, and yogurts. The good news is that vitamin D can be made in our skin when we are exposed to direct sunlight.

Many people don't get enough vitamin d every day. In fact, new recommendations have doubled the requirement for both children and adults. Most adults need at least 800 units every day.

So, are you getting enough vitamin D? It depends a lot on your age, where you live, and your use of sunscreen. Plus, if you're a senior, or have darker skin, production of vitamin d is also reduced.

My bottom line? Vitamin D is crucial for bone health and maintenance. If you think you're not getting enough, try adding more vitamin-d enriched food in your diet and increase your daily sun exposure. Consider a multivitamin or calcium supplement containing 100% of your daily vitamin D requirement.

Can bone loss be prevented? Most of us think about thinning bones as a natural part of mid-life that can't be prevented. While it's true that there are a few contributors to bone strength that are out of our control--like our family history and declining estrogen levels--there are multiple lifestyle activities we can incorporate into our daily lives to keep our bones strong. It's never to early, or too late!

The three pillars of lifestyle that support healthy and strong bones are:

1. Calcium intake
2. Vitamin D intake
3. Weight-bearing physical activity

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Most adults need 1000 mg of calcium every day (post-menopausal women need about 1200 - 1500 mg daily). It's best to get calcium from food, and while dairy products are the most concentrated form of calcium, dark green vegetables, and some nuts and seeds can contribute dietary calcium. If you don't consume dairy products, you'll have to work harder to maintain adequate calcium intake.

Where is calcium found in the diet?

Dairy foods, including milk, yogurt, and hard cheeses contain about 300-400 mg calcium per serving. Fat free, low fat, or full fat products all have the same amount of calcium. Cottage cheese is not calcium-rich and joins the "calcium-fortified" food category.

Broccoli has about 180 calories per cup, while 2 cups of arugula have 250 mg. Nuts and seeds have 50-100 mg per ounce, while 1 cup of dried figs contains 300 mg of calcium. If you're a lover of bony fish--like sardines, and canned salmon--you'll get nearly a glass of milk's worth of calcium in a 3 ounce serving.

Calcium fortified foods--those that don't normally contain calcium, but to which some is added--include orange juice, cottage cheese, cereals, soy milk and brown rice.

The Connection Between Vitamin D and Bone Health

While Vitamin D is linked to good health in many ways, when it comes to bone health, its main role is to enhance the absorption of calcium into the digestive tract. Most foods are very low in Vitamin D, which is not a surprise, once you know that it can be synthesized in the skin, when exposed to sunlight (without sunscreen). Just 10-15 minutes a day provides enough vitamin D to meet daily requirements. While 400 IU is still the official requirements, mid-life women and older are recommended to consume 800 IU daily. But with sunscreen and increased time spent indoors we often need supplements. Dairy products are vitamin D fortified--providing a real "double duty" food. Fatty fish like salmon and mackerel are also Vitamin D rich. Smaller amounts are found in mushrooms, shrimp, and eggs. A daily multiple vitamin pill is fortified with 400 IU of vitamin D, as is almost all types of calcium supplements.