More than half of Americans take a dietary supplement; calcium and vitamin D are among the most common. The two supplements are generally okay to take together with healthcare provider guidance. However, research has been mixed about whether the two can be taken at the same time.
Still, you don't have to rely on supplements to get the calcium and vitamin D you need if you're in generally good health. Here's what you should know about taking these supplements together.
Most of the body's calcium supply—about 98%—can be found in one's bones. Having enough calcium is important for:
- Blood clotting
- Blood vessel contraction and dilation
- Bone health
- Hormonal secretion
- Muscle function
- Nerve communication
How Much We Need
Adults need the following daily amounts of calcium:
- Adults assigned male at birth, aged 19-70: 1,000 milligrams (mg)
- Adults assigned male at birth, aged 70+: 1,200mg
- Adults assigned female at birth, aged 19-50: 1,000mg
- Adults assigned female at birth, aged 51-70+: 1,200mg
- Pregnant people: 1,000mg
- People who are lactating: 1,000mg
Why We Need Vitamin D
Vitamin D, which is important for children and adults, also protects bones and helps support your muscles. It's also necessary to help with:
- Calcium absorption
- Immune system functioning
- Nerve communication
Among the most popular ways to get vitamin D is going outside. When sunlight reaches your skin, your body makes and stores vitamin D.
How Much We Need
Adults need the following daily amounts of vitamin D:
- Adults assigned male at birth, aged 19-70: 15 micrograms (mcg)
- Adults assigned male at birth, aged 70+: 20mcg
- Adults assigned female at birth, aged 19-70: 15mcg
- Adults assigned female at birth, aged 70+: 20mcg
- Pregnant people: 15mcg
- People who are lactating: 15mcg
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Stephen Kopecky, MD, a cardiologist at Mayo Clinic, told Health you shouldn't panic if you've been taking vitamin D and calcium supplements together. Dr. Kopecky added that many of the studies that have looked at the use of vitamin D and calcium supplements rely on follow-up data that lacks precision.
Additionally, researchers indicated in a 2019 study that taking calcium and vitamin D supplements together might increase your risk of stroke. However, the authors had looked at previously published evidence concerning how supplements affect human health.
Other researchers have found that using calcium and vitamin D supplements is fine in moderation—particularly for older adults. However, excessive use of the two supplements is not overly beneficial.
Risks and Side Effects
It's good to have adequate amounts of vitamin D and calcium to help your body function. However, the supplements can have drug interactions. It's also possible to have too much of these nutrients in your body from taking supplements.
Medication Interactions
Both supplements can also interact with certain types of medications. Calcium supplements might have interactions with:
- Dolutegravir, an HIV medicine
- Levothyroxine, a thyroid hormone
- Lithium, a bipolar disorder medicine
- Quinolone antibiotics
Vitamin D supplements can have interactions with:
- Cholesterol-lowering statins
- Orlistat, a weight loss drug
- Steroids
- Thiazide diuretics, medicines for high blood pressure
Risks
Very high levels of vitamin D in the body usually come from taking too much vitamin D supplement. Risks of those high levels include:
- Death
- Irregular heartbeat
- Kidney failure
You may have high levels of calcium from supplementation. However, the high levels are usually the result of a health condition rather than supplements. Still, the risks of high calcium intake are:
- Abnormal heart rhythms
- High risk of heart disease-related death
- Increased risk of kidney stones, also known medically as nephrolithiasis
Side Effects
Calcium and vitamin D supplements don't come without potential side effects. As you increase how much of each nutrient is in your body, you could collectively experience:
- Appetite loss
- Confusion
- Constipation
- Dehydration
- Excessive urination and thirst
- Extreme tiredness
- Low levels of phosphate
- Muscle weakness
- Nausea or vomiting
- Pain
- Poor kidney functioning
- Poor muscle tone
- Weight loss
The FDA minimally regulates dietary supplements, which may or may not be suitable for you. Speak with a healthcare provider or pharmacist before starting any supplements. Here's what else to consider about supplementing calcium and vitamin D.
Dosage
For calcium, the safest amount an adult can have daily when taking supplements and getting calcium from foods and drinks is 2,500mg daily. Your body can absorb calcium best at 500mg or less daily. It's best to spread calcium supplement intake across your day.
The vitamin D upper limit for adults is 100mcg daily, including amounts from what you eat and drink along with supplements. Unless you've been diagnosed with a vitamin D deficiency, ensure that your supplement alone won't result in you reaching your daily limit of 100mcg.
Consult a healthcare provider to determine if you need to take both together. Vitamin D may be available in some types of calcium supplements.
Timing
The type of calcium supplement will depend on when you need to take it. If you're using a calcium carbonate supplement, you should use it when you're eating a meal. You can take calcium citrate supplements with or without food.
Vitamin D is fat-soluble, meaning that it can break down in fat. To best absorb the vitamin in its supplement form, take it when eating meals or snacks with fat content.
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Best Sources of Vitamin D and Calcium
Dr. Kopecky added that if you've been told to take calcium and vitamin D supplements by a healthcare provider, you shouldn't stop. Yet, if you're worried about your calcium and vitamin D intake and don't take either supplement, consider making dietary changes where possible.
Vitamin D
Vitamin D is naturally available in limited food sources. Still, to increase your intake of vitamin D, try some of these nutrient-rich options:
- Braised beef liver
- Egg yolks
- Fatty fish like mackerel, salmon, trout, and tuna
- Fish liver oils
- Mushrooms
- Vitamin D-fortified products, such as cereals, milk, and plant-based milk
Calcium
If you want to ensure you're getting enough calcium, many dairy options have the mineral—including cheese, milk, and yogurt. Other foods you could eat:
- Boiled spinach
- Calcium-fortified products
- Fresh kale
- Salmon
- Tofu
- Turnip greens
Research has been mixed about whether vitamin D and calcium supplements can be taken together. However, they are generally okay to take at the same time, with direction from a healthcare provider.
Using vitamin D and calcium supplements comes with possible risks and side effects. However, you can reduce the risks and side effects by taking them properly or increasing your dietary vitamin D and calcium intake instead.
