Can I take a calcium supplement together with milk?

Milk and a calcium supplement are both calcium, so they count towards the same daily total. The Thai Reference Daily Intake (Thai RDI) for calcium is 1,000 mg a day, and the US upper limits published by the NIH Office of Dietary Supplements (ODS) count calcium from food, drinks and supplements together: 2,500 mg a day for adults aged 19 to 50 and 2,000 mg for adults over 50. Before adding a supplement, add up what comes from milk, other foods and every product you use, and show the products to a pharmacist, especially if you take regular medicines.

In short:

• What to look at: the total calcium from milk, food, supplements and any other products
• Daily reference: Thai RDI 1,000 mg
• Upper limit (US, all sources): 2,500 mg at 19 to 50, 2,000 mg over 50
• Who to ask: a pharmacist, with every product and medicine you use

This article is about adding calcium from milk and from supplements together. For the full list of calcium-rich foods, see Which foods are high in calcium, and how much is in each?, and for the forms of calcium in supplements, see What forms does calcium come in, and how do they differ?

How do milk and a calcium supplement add up?

Milk and a calcium supplement both count towards the same daily total. Milk is one of the main food sources of calcium, and a calcium supplement is another source of the same mineral.

Public limits count every source

The ODS says the daily upper limits for calcium include intakes from all sources: food, beverages and supplements. So a glass of milk at breakfast, yoghurt in the afternoon and a supplement in the evening all count towards the same daily number. The National Institute on Aging (NIA), also part of the US National Institutes of Health, puts it this way: when thinking about whether you need more of a vitamin or mineral, think about how much you get from food and drinks, as well as from any supplements you take.

What calcium does

Calcium is needed for the maintenance of normal bones and teeth. Getting more than you need does not add anything extra on top, which is why the total is worth checking before adding a product.

How much calcium is in milk and dairy foods?

The figures below come from the US Department of Agriculture's FoodData Central database (SR Legacy), per 100 g. These are amounts in 100 g of food, not the per-serving figures on a label.

Soy drinks depend on what is added

The two soymilk rows show why the label matters. The ODS notes that calcium is added to some drinks, including many milk substitutes such as soy and almond drinks, and to some brands of tofu and cereals, and that the product label tells you whether calcium has been added.

Reading a Thai nutrition label

On Thai nutrition labels, vitamins and minerals are shown as a percentage of the Thai RDI. For calcium, that percentage is out of the Thai RDI of 1,000 mg and refers to one serving. Look at the serving size too, since one carton or bottle may be more than one serving.

How much calcium do Thai people get from food?

Thai studies show a wide range, which is one reason a single rule for everyone does not work.

What these numbers can and cannot tell you

Each study looked at one group in one area, and food intake was estimated from what people reported eating, so the figures are not national averages. The pregnant women in Khon Kaen were a specific group whose diets may differ from other adults. Taken together, though, they show that some people get far less than 1,000 mg from food while people who drink milk every day can already get more than 1,000 mg from food alone. Adding a supplement on top changes the total differently for each of them.

How much is enough, and how much is too much?

Side effects people notice

The ODS says calcium supplements might cause gas, bloating and constipation in some people. The NHS page on calcium says taking high doses of calcium, more than 1,500 mg a day, could lead to stomach pain and diarrhoea. On the same page, the UK Department of Health and Social Care advises that you should be able to get all the calcium you need from a varied and balanced diet, that if you take calcium supplements you should not take too much, as this could be harmful, and that taking 1,500 mg or less a day is unlikely to cause any harm.

Where else might calcium be coming from?

Milk and a calcium tablet are the obvious sources. Others are easy to miss.

Other products that can contain calcium

The ODS lists:

• multivitamin and mineral supplements
• supplements that combine calcium with other nutrients, such as vitamin D
• some over-the-counter antacids, which contain calcium carbonate
• foods and drinks with calcium added, such as some soy and almond drinks, tofu and cereals

The ODS also notes in its guide Dietary Supplements: What You Need to Know that because vitamins and minerals are added to foods, you may get more of these ingredients than you think, and more might not be better.

Many Thai adults already use herbs or supplements

A survey by Wongtaweepkij and colleagues in public places in a large city in northeastern Thailand found that 540 respondents (51.0%) used herbs or dietary supplements, and 59.3% of users wanted more information about interactions with medicines. The people were not chosen at random, so the figures describe that group rather than all Thai adults.

What should you check before adding a calcium supplement?

Make one list

The ODS suggests keeping a complete record of the dietary supplements and medicines you take, noting for each product its name, the dose, how often you take it and why. Add how much milk, yoghurt or soy drink you usually have in a day.

Check the calcium on each label

Look for the amount of calcium the label gives for each product. How calcium compounds are labelled is explained in What forms does calcium come in, and how do they differ?

Show the list to a pharmacist

The ODS says calcium supplements can interact with or interfere with certain medicines, and some medicines can lower calcium levels in the body. It advises telling your doctor, pharmacist and other health care providers about every supplement and medicine you take, so they can tell you whether there may be an interaction. Ask the pharmacist about the total and about timing with any medicine, rather than working it out on your own. The NIA also suggests using one pharmacy where you can, so your records are in one place, or sharing your list of medicines and supplements with the pharmacist at each place you use.

Who should talk to a doctor or pharmacist?

People who take regular medication

If you take medicine regularly, ask a doctor or pharmacist before adding a calcium supplement, and bring all your products with you.

Pregnant and breastfeeding women

If you are pregnant or breastfeeding, talk to a doctor or pharmacist before taking any dietary supplement, including calcium.

Dietary supplements are not intended to prevent, treat or cure any disease.