Odds are, you think of your skeleton as a fixed part of you — your body’s unchanging foundation. But really, over time, our bones are constantly building up and breaking down again. The process is so gradual, we usually don’t notice. In fact, you may not even think twice about your bones until something goes wrong, like a hip or wrist fracture.

In years past, to strengthen bones and prevent those breaks, many healthcare providers (HCPs) told their patients to take calcium or vitamin D supplements. But there’s a growing understanding that this recommendation may not really be effective for most people.

In fact, in 2018 the U.S. Preventive Services Task Force (USPSTF) released a statement stating that, with exceptions, there wasn’t good evidence that lower doses of calcium or vitamin D supplements could help ward off fractures, particularly among postmenopausal women — and at higher doses, they may actually increase the risk of kidney stones. The Task Force noted that more research is needed to determine if the possible benefits of these supplements outweigh the risks for certain people.

“To just recommend [supplementing] broadly to everybody is really falling out of favor,” says Lawrence Conley, DO, an HCA Healthcare orthopedic surgeon. “You have to look at everybody differently. It’s very multi-faceted.”

To build strong bones, you need calcium and vitamin D. But your body relies on these nutrients for many other critical functions. Your muscles, nerves and blood vessels need calcium to function properly. It’s also essential for healthy teeth. Vitamin D may also support your muscles and immune system.

Many people are able to get adequate amounts of calcium and vitamin D through their diet alone, but some may need supplements. Some studies suggest that supplements could help certain groups at higher risk for deficiencies. And while we don’t know exactly how effective the supplements are, or whether they benefit everyone — like African Americans, for example, who have greater bone density than other racial groups — they may work for some people.

Here’s the lowdown.

When to bone up on calcium

Nearly all — 99 percent — of the calcium in your body is stored in your bones and teeth. So, when you don’t have enough, your body begins to draw it from your skeleton. This may not be obvious right away. But over time, too much of this is one possible cause of osteoporosis, a disease that causes bones to weaken and become prone to fracture. A costly condition to treat, osteoporosis is a major contributor to fractures among older people and increases chances of early death.

Since we’re unable to make it on our own, we get calcium through our diets — and most of us are far from deficient. It’s in a wide variety of foods, including leafy greens, salmon (particularly canned salmon with bones), white beans, tofu and especially dairy items, not to mention products to which it’s purposely added.

“It’s hard in America today not to get enough calcium because we fortify everything,” says Dr. Conley. “Our cereals are fortified with it. Our milk is fortified with it. You can get a whopping dose in just two glasses of milk a day.”

That said, as we age, our bodies get worse at absorbing and conserving calcium, and certain people may not get enough. Those most susceptible to deficiency include postmenopausal women, people with medical conditions that interfere with absorption and those following dairy-free diets, like vegans and people who are lactose intolerant, or have trouble digesting a sugar naturally found in milk and milk products.

In these cases, HCPs may propose calcium supplements to make up the difference. (Keep in mind, recommended daily allowances, or RDAs, are determined for overall health — not specifically for fracture prevention). The dosage depends on the particular situation, but the total RDA for most men and pre-menopausal women is about 1,000 milligrams (mg). After menopause, women should get about 1,200 mg. The same dose is recommended for men age 71-years and older.

Keep in mind however, taking too much is risky. It’s generally agreed that if you’re between 19 and 50 years old, your calcium intake shouldn’t exceed 2,500 mg per day. If you’re 51 years or older, you shouldn’t get more than 2,000 mg per day. These limits will help you avoid minor side effects like indigestion, as well as more serious issues like a possible increased risk of heart disease. High intake of calcium from supplements has also been associated with increased risk for kidney stones.

It’s important to note that getting too much calcium from foods is rare. In most cases, excess intake is due to supplement use.

Two of the most popular supplements are calcium carbonate and calcium citrate. Both are available without prescription. Calcium carbonate may be less expensive and should be taken with food. Calcium citrate, on the other hand, can be better absorbed by some people and doesn’t require you to eat with it. Many calcium supplements come with vitamin D, as well, since it helps with absorption. (More on that in a bit.)

You may tolerate calcium supplements better if you start by taking a small daily dose of 200 to 300 mg for seven days with plenty of water. Then, work your way up gradually, adding more calcium each week until you reach the dose recommended by your doctor. It’s also a good idea to split up your dosage.

Calcium is absorbed best when taken in smaller amounts of 500 to 600 mg or less, preferably with a meal. Some people who take calcium supplements experience side effects like constipation or gas. In that case, let your HCP know — and definitely give them a heads up if you’re on other medications, since any supplement can interact with them.

Looking at vitamin D

Whereas calcium builds strong bones, vitamin D makes it possible by helping your body to absorb that calcium. In other words, says Conley, “Calcium is in the front row in the band, but vitamin D is actually leading the band.”

Too little vitamin D can result in thin, soft, brittle bones. In kids, this is called rickets. Among adults, this condition is known as osteomalacia and it increases your odds of osteoporosis.

The recommended daily allowance varies by the organization offering the guidance and may also differ from person to person. The government suggests people between 1 and 70 years old get 600 International Units (IU) of vitamin D per day. Once you hit 71, it rises to 800 IU. Other guidelines may recommend that women increase their vitamin D intake to 800 IU daily once they reach menopause.

Unlike calcium, it’s tough getting sufficient vitamin D from your diet, since it’s found in only a few foods. Fatty fish like salmon and tuna are leading natural sources, and some items like milk, orange juice, yogurt and cereal may be fortified with it, too.

Here’s the thing, though: Vitamin D is actually a hormone that we can create ourselves when sunlight hits our skin. Then, our liver and kidneys turn it into a compound that helps build our skeletons.

As with calcium, many people don’t need a vitamin D supplement, though certain groups with increased chances of deficiency may benefit, like seniors. When we grow older, Conley says, our skin is less efficient at creating vitamin D. What’s more, many older adults don’t get outside enough to receive adequate sunlight, particularly those in nursing homes or other care facilities.

Others at risk include people with darker skin, who don’t create vitamin D as efficiently as those with lighter skin. People who are obese and those with medical conditions interfering with absorption, like Crohn’s disease, also have higher odds of a deficiency.

If your HCP recommends a vitamin D supplement, it could be either D3 (cholecalciferol) or D2 (ergocalciferol). Some experts recommend D3 instead of D2. “You can get a number of different supplements over the counter,” says Conley, and many come in a combination pill with calcium. Your dosage will hinge on your circumstances, and you won’t need to take them with food.

Important to know: The maximum recommended dose of vitamin D is about 4,000 IUs, and very high doses are possibly toxic. Taking too much can cause a host of symptoms including nausea, weakness, weight loss and heart rhythm problems. High vitamin D levels can also raise blood calcium levels, which can lead to heart, blood vessel and kidney damage.

Supplement tips

If supplements are the right choice for you, be sure to follow your HCP’s dosage recommendations. More is not necessarily better, says Conley, and overdoing it can lead to other health problems.

Be aware, too, that a general-purpose multivitamin may not have enough calcium or vitamin D for your needs. If you take a multivitamin, check it to see how much of these nutrients are in it and be sure to count that toward your daily intake. It’s also important to look for symbols on product labels that signify high quality, like “purified” or “USP Verified Mark.”

Most of all, understand that while supplements can help, they can’t protect your bones all by themselves. Along with eating well, you need to take other steps — one of which is literally taking steps.

“You’ve got to exercise,” says Conley. “You can have plenty of vitamin D. You can have plenty of calcium. But if you’re somebody who sits more days than not, your bones are not going to be as dense as they should be.” He recommends weight-bearing workouts — even if it’s just walking around the mall with friends.

Experts also suggest that not smoking, limiting your alcohol use and knowing your family health history are all parts of a smart bone-health strategy. And if you’re a woman age 65 or older or at high risk for osteoporosis, speak to your HCP about a bone density test.

Ultimately, while supplements may play a role, your bone health is in your hands.

This content originally appeared on Sharecare.com.