About 99% of the calcium in your body is stored in your bones and teeth, and the 206 bones of the adult skeleton act as a living mineral bank you draw on every day. Vitamin D is the key that lets your gut absorb calcium in the first place. Getting enough of both throughout life helps you build strong bones when you are young and slow the losses that come with age. This guide explains how much you need, where to find it in everyday foods, and how to avoid getting too much.
Why calcium and vitamin D matter for bones
Bone is not a static material. Throughout your life, specialized cells break down small amounts of old bone while others lay down new bone in its place. Calcium is the main mineral that gives that new bone its hardness. If you do not take in enough, your body keeps blood calcium steady by pulling it out of the skeleton, which over years can leave bones thinner and more likely to break.
Vitamin D works alongside calcium. Without enough of it, your intestines absorb only a fraction of the calcium you eat, no matter how much is on your plate. Children who are badly short of vitamin D can develop rickets, and adults can develop soft, weak bones. In later life, low calcium and vitamin D intake are two of the modifiable factors linked to osteoporosis.
Most bone is built during childhood and the teen years, and bone mass generally peaks in early adulthood. After that, the goal shifts from building to protecting what you have, which is why recommendations change across the lifespan.
How much calcium and vitamin D you need
The table below shows the Recommended Dietary Allowances (RDAs) published by the NIH Office of Dietary Supplements, along with the Tolerable Upper Intake Level (UL) for calcium. The RDA is the daily amount that meets the needs of nearly all healthy people in a group. The UL is the highest daily intake from all sources, food and supplements combined, that is unlikely to cause harm. It is a ceiling, not a target.
| Life stage | Calcium RDA | Calcium upper limit | Vitamin D RDA |
|---|---|---|---|
| Children 1–3 | 700 mg | 2,500 mg | 600 IU (15 mcg) |
| Children 4–8 | 1,000 mg | 2,500 mg | 600 IU (15 mcg) |
| Children 9–13 | 1,300 mg | 3,000 mg | 600 IU (15 mcg) |
| Teens 14–18 | 1,300 mg | 3,000 mg | 600 IU (15 mcg) |
| Adults 19–50 | 1,000 mg | 2,500 mg | 600 IU (15 mcg) |
| Men 51–70 | 1,000 mg | 2,000 mg | 600 IU (15 mcg) |
| Women 51–70 | 1,200 mg | 2,000 mg | 600 IU (15 mcg) |
| Adults over 70 | 1,200 mg | 2,000 mg | 800 IU (20 mcg) |
| Pregnant or breastfeeding, 14–18 | 1,300 mg | 3,000 mg | 600 IU (15 mcg) |
| Pregnant or breastfeeding, 19–50 | 1,000 mg | 2,500 mg | 600 IU (15 mcg) |
Two patterns stand out. First, the years from 9 to 18 have the highest calcium target of any age group, because this is when the skeleton grows fastest. Second, women's needs rise at 51, reflecting faster bone loss after menopause. The upper limit for vitamin D is 4,000 IU a day for anyone 9 and older. Want a personal estimate? Try our calcium calculator to total what you eat on a typical day.
Best food sources of calcium
Food is the preferred way to meet your calcium needs because it brings other nutrients along with it. Dairy products are the largest source for many people, but there are plenty of options for those who avoid milk. The values below come from the NIH Office of Dietary Supplements and the Dietary Guidelines for Americans; brands vary, so check the Nutrition Facts label on packaged foods.
| Food | Serving | Calcium (mg) |
|---|---|---|
| Almond beverage, unsweetened, fortified | 1 cup | 442 |
| Yogurt, plain, low fat | 8 ounces | 415 |
| Orange juice, calcium fortified | 1 cup | 349 |
| Mozzarella, part skim | 1.5 ounces | 333 |
| Sardines, canned in oil, with bones | 3 ounces | 325 |
| Milk, nonfat | 1 cup | 299 |
| Soy beverage, calcium fortified | 1 cup | 299 |
| Collard greens, cooked | 1 cup | 268 |
| Tofu, firm, made with calcium sulfate | 1/2 cup | 253 |
| Salmon, pink, canned, with bones | 3 ounces | 181 |
| Tahini (sesame paste) | 1 tablespoon | 154 |
| Kale, cooked | 1 cup | 94 |
| Chia seeds | 1 tablespoon | 76 |
| Almonds | 30 grams (about 1 ounce) | 75 |
| Bok choy, raw, shredded | 1 cup | 74 |
| Broccoli, raw | 1/2 cup | 21 |
Not all calcium is absorbed equally
The number on a label tells you how much calcium a food contains, not how much your body keeps. Spinach is the classic example. It looks impressive on paper, but it is high in oxalate, a natural compound that locks calcium into a form your gut cannot use. NIH data show only about 5% of the calcium in spinach is absorbed, compared with roughly 27% from milk. Rhubarb, sweet potatoes and beans also contain compounds that reduce absorption.
In contrast, low-oxalate greens such as kale, bok choy and broccoli release their calcium about as well as milk does. The catch is that a serving holds far less calcium, so they work best as part of a mix rather than as your only source.
Where to get vitamin D
Vitamin D is unusual because your skin can make it when exposed to the sun's ultraviolet B (UVB) rays. How much you make depends on the season, time of day, latitude, cloud cover, skin tone and sunscreen use. Older adults and people with darker skin make less, and UVB does not pass through window glass. Because ultraviolet exposure is also the most preventable cause of skin cancer, health agencies do not recommend relying on deliberate sun exposure or tanning beds.
Few foods are naturally rich in vitamin D. According to NIH figures:
- Fatty fish are the best natural source: 3 ounces of cooked farmed rainbow trout has about 645 IU, and the same amount of cooked sockeye salmon about 570 IU.
- UV-exposed mushrooms can be a good plant source, with about 366 IU in half a cup of sliced raw white mushrooms treated with UV light.
- Fortified foods supply most of the vitamin D in the US diet: about 120 IU per cup of fortified milk, roughly 100 to 144 IU per cup of fortified soy, almond or oat beverage, and around 80 IU in a serving of fortified cereal.
- Smaller amounts come from eggs (about 44 IU in a large egg, all in the yolk), canned light tuna and cheese.
Many people find it hard to reach 600 to 800 IU a day from food alone, especially in winter or if they spend most of their time indoors. Groups who may need extra attention include breastfed infants, older adults, people with darker skin, people with limited sun exposure, and those with conditions that affect fat absorption. A clinician can check your blood level and advise whether a supplement makes sense for you.
Absorption tips and calcium supplements
If you cannot meet your needs through food, a supplement may help fill the gap. A few practical points from the NIH fact sheets can make it work better:
- Keep each dose to about 500 mg or less. Absorption falls as the dose rises. Splitting a larger daily amount into a morning and evening dose usually gives better results.
- Know your form. Calcium carbonate needs stomach acid to dissolve, so it is best taken with a meal. Calcium citrate depends less on stomach acid and can be taken with or without food, which may suit people with low stomach acid or those taking acid-reducing medicines.
- Check the elemental calcium. The label's Supplement Facts panel lists the actual calcium per serving; use that figure, not the total weight of the compound.
- Count everything. Add up food, fortified products and supplements before deciding how much extra you need. Many people need far less from a pill than they assume.
- Watch for side effects. Gas, bloating or constipation sometimes occur. Spreading doses out, taking them with meals or switching forms may help.
Calcium supplements can interact with some prescription medicines, including certain antibiotics and thyroid medicine. Ask your pharmacist how to time them.
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Protein, vitamin K, magnesium and the bigger picture
Calcium and vitamin D get most of the attention, but bone is a complex tissue that relies on many nutrients. Bone minerals are laid down on a protein framework made mostly of collagen. Getting enough protein from foods such as fish, eggs, dairy, legumes, tofu and nuts supports that framework and the muscles that load your bones.
Vitamin K helps activate proteins involved in bone mineralization, and leafy greens are a major source. Magnesium is another mineral stored largely in bone and is found in nuts, seeds, whole grains and legumes. Research on how much these nutrients influence fracture risk is still developing, and supplements are not a substitute for a balanced diet. If you take a blood thinner, talk to your clinician before changing how much vitamin K you eat, because large swings can affect how the medicine works.
Diet is only part of the story. Regular weight-bearing and strength exercise, not smoking and limiting alcohol all matter too. Our guide to exercises for strong bones covers the movement side.
Risks of getting too much
More is not better. Most people who eat a varied diet do not come close to the calcium upper limit from food alone; problems usually come from high-dose supplements stacked on top of fortified foods. The NIH notes that some observational data linked higher supplemental calcium intake to kidney stones, though later systematic reviews did not find the same link. Because of that uncertainty, it is sensible to aim for your RDA rather than far above it, and to discuss supplements with your clinician if you have a history of kidney stones.
Excess vitamin D is almost always caused by taking too many supplements, not by sunshine or food. Very high blood levels can cause nausea, vomiting, muscle weakness, confusion, excessive thirst and urination, and kidney stones; extremely high levels can be dangerous. Stay at or below 4,000 IU a day unless a clinician has prescribed a different amount and is monitoring you.
Plant-based and lactose-free options
If you are lactose intolerant, you may still tolerate small portions of milk with meals, yogurt with live cultures, hard cheeses or lactose-free milk, all of which keep their calcium. Fully dairy-free eaters can build a calcium-rich day around:
- Tofu made with calcium sulfate (look for it in the ingredient list)
- Fortified soy, almond, oat or rice beverages; shake the carton, because added calcium can settle at the bottom
- Fortified orange juice and fortified cereals
- Low-oxalate greens such as collards, kale and bok choy
- Tahini, chia seeds and almonds as smaller top-ups
- Canned sardines or salmon with the soft bones left in, for those who eat fish
Unfortified plant beverages can contain very little calcium, so reading the label is essential.
A sample day that reaches 1,000–1,200 mg
Here is one way an adult could reach their target with ordinary meals. Amounts use the values in the table above.
Mixed diet: about 1,150 mg
Breakfast: 8 ounces of plain low-fat yogurt with 1 tablespoon of chia seeds and berries (415 + 76 = 491 mg).
Lunch: salad with 3 ounces of canned pink salmon with bones and a side of raw broccoli, half a cup (181 + 21 = 202 mg).
Snack: 30 grams of almonds (75 mg).
Dinner: stir-fry with 1 cup of cooked kale and a glass of nonfat milk (94 + 299 = 393 mg).
Total: about 1,161 mg, plus small amounts from bread and other foods.
Dairy-free: about 1,100 mg
Breakfast: fortified cereal with 1 cup of fortified soy beverage (130 + 299 = 429 mg).
Lunch: grain bowl with half a cup of firm calcium-set tofu and 1 tablespoon of tahini dressing (253 + 154 = 407 mg).
Dinner: 1 cup of cooked collard greens alongside beans and rice (268 mg).
Total: about 1,104 mg.
Spreading calcium across meals, as in these examples, also helps absorption, since no single meal delivers much more than 500 mg.
When to talk to a clinician
Consider a conversation with your doctor or a registered dietitian if you have had a fracture from a minor fall, have a family history of osteoporosis, have gone through early menopause, take long-term steroid medicines, have a digestive condition such as celiac or Crohn's disease, or follow a restrictive diet. They can review your intake, check vitamin D levels if appropriate, and decide whether a bone density test is worthwhile. You can also take our quick bone health risk check to see which factors apply to you.
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The bottom line: aim for your age-appropriate RDA, mostly from food, spread through the day; get vitamin D from fortified foods, fatty fish and, where needed, a supplement your clinician approves; and pair good nutrition with regular movement for bones that stay strong for life.