Design a site like this with
Get started

The Brittle Relationship Between Calcium, Your Bones, and Your Microbiome.

How Much Calcium Do You Need and What is the Best Way to Get It?

Calcium is an essential mineral for strong bones, nerve conduction, heart health, muscle function, as well as cancer protection. Getting enough calcium while you’re young is vitally important for your bone density. Ninety percent of your bone is acquired by age 20. Without adequate calcium intake and exercise in the first two decades of life, it’s virtually impossible to develop enough bone density to prevent osteoporosis later in life, and yet, a quarter of American kids don’t get enough calcium and over 70% don’t get enough exercise. 

Americans get most of their calcium from dairy products. Unfortunately, the majority of the world’s population (68%) has some degree of lactose intolerance by the time they finish elementary school. (Lactose intolerance means that eating dairy foods causes gas, bloating, diarrhea, or abdominal discomfort, usually within 30 minutes to 2 hours.) Others choose not to eat dairy products for health or philosophical reasons. 

There are very few non-dairy foods in nature that have a significant amount of calcium. Healthy foods like green leafy vegetables, cruciferous vegetables, nuts, seeds, beans, and oranges have some calcium, but you would have to eat many large servings of them every day to get enough. Calcium-fortified tofu, cereal, juice, and plant-based milk substitutes have significant calcium content only because they have a supplement added to them.

It’s very difficult to get the US Recommended Daily Allowance of calcium (1,300mg for teens and 1000mg for adults) without consuming 2 or 3 servings of dairy foods a day or by taking supplements. 

So why is it so difficult to get the recommended amount of this essential nutrient without eating dairy, a food that causes problems for two-thirds of the human population?

Unfortunately, that is a very complex question. Our ability to make healthy bone depends on much more than our calcium intake. The USRDA for calcium is 1000mg, the UK recommends only 700mg a day and the World Health Organization recommends just 500mg a day. Why such a huge discrepancy?

The reason is that the amount of calcium you need for healthy bone is directly related to everything else you eat, how and where your food is grown, how much Vitamin D you get from the sun and from foods, what kind of microbes live in your gut, what foods or supplements you eat at the same time and much more.

The American RDA is high because there are factors in the Standard American Diet (S.A.D.) and lifestyle that either prevent calcium from being absorbed by the colon or cause calcium to be leached out of the bone and excreted in the urine. Diets high in animal protein, salt, caffeine, alcohol, or soda, especially colas, increase your calcium requirement. The S.A.D. is full of salty processed foods, meat, caffeinated beverages, and soft drinks. Most Americans need to eat more calcium to make up for the problems their eating habits cause.

I will explain the details of this complex issue in the box below. If you prefer to skip the details, scroll down to my recommendations for how much, how often, which foods, and which supplements might work best for you.

  • The type of bacteria (probiotics) that grow in your colon determines how much calcium you absorb.  Eating foods like yogurt or taking a supplement that contains probiotics increases the beneficial bacteria in your colon for a day or two (until you poop them out), but eating fiber-containing fruit, vegetables, beans, whole grains, nuts, and seeds supports the beneficial probiotics and makes them stay in your colon helping you continue absorbing calcium. Most Americans don’t eat enough of these foods.
  • Smoking and vaping interfere with bone formation in several ways. Fourteen percent of Americans smoke.
  • Modern American agriculture which depletes the soil of nutrients has reduced the amount of calcium contained in our produce by 25 to 30%, which makes adequate calcium intake from a vegan diet almost impossible without supplements. (Plant milk, tofu, and other vegan foods like cereals contain calcium supplements because they don’t naturally have much calcium.) 
  • The amount of calcium you absorb is decreased by eating foods or supplements that contain large amounts of magnesium, zinc, or iron at the same time. Avoid taking these supplements at the same time as your high calcium foods or calcium supplements.
  • Getting enough Vitamin D from the sun, your food, or a supplement increases calcium absorption. Many Americans don’t get enough sun exposure to make sufficient Vitamin D. If you take a Calcium supplement, take 400 to 1000IU vitamin D with it.
  • Exercise increases the amount of calcium you add to your bone. Daily exercise should be moderate to vigorous and involve work against gravity to build strength: walking, running, lifting weights, etc. Most Americans don’t exercise enough.
  • Maintaining a healthy weight helps you optimize bone building. Being too thin can prevent you from developing enough bone mass, and being overweight depletes you of Vitamin D which is essential for Calcium absorption. Nineteen percent of young Americans are overweight and 42% of adults.
  • Getting enough Vitamin K and magnesium helps you convert calcium in your diet into strong bones and prevents the calcium you consume from ending up in your arteries (atherosclerosis) and kidneys (kidney stones) instead. These two key nutrients are both found in green leafy vegetables. Only 10% of Americans eat enough produce. Aim for at least 2 of your 5 daily servings of fruits and vegetables to be dark green leafy vegetables, for example, 2 cups of lettuce or 1 cup of broccoli.

How to Get Enough Calcium:

The following foods contain about a third of your calcium needs. If you eat 3 of the following foods a day, you don’t need a supplement. If you get only one or two of these foods most days, take a supplement once a day. If you never or rarely eat these foods take a supplement twice a day.

  • 8 ounces of yogurt,
  • 1 ounce of cheese
  • 8 ounces of milk
  • 8 oz fortified dairy substitutes (not all plant milk or plant yogurt is fortified with calcium and vitamin D-check the label)
  • tofu or tempeh made with calcium sulfate

You can calculate the amount of calcium in your diet with this calcium calculator.

Here is a list of foods and the calcium they contain.

How much calcium to take

A calcium and vitamin D supplement containing 300 to 500mg calcium and 400 to 1000IU of vitamin D once or twice a day as needed to provide the calcium needed to get you to your RDA. While taking supplements does have risks, the risk of not getting enough calcium during the first 2 decades of life is greater. If you’re not sure if you get enough calcium and vitamin D, it is safer to supplement.

Consider the following supplements and consult your doctor:

Caltrate Bone Health, ½ tablet or chew once or twice daily.

Jarrow formulas Bone Up, 2 caplets once or twice a day

In addition to getting enough calcium and vitamin D,

  • Eat 5 or more servings of fruit and vegetables a day
  • Make 2 of those servings of green leafy veggies
  • Eat 3 servings of whole grains a day and avoid processed foods
  • Eat one or more servings of nuts or seeds a day
  • Avoid alcohol
  • Don’t smoke or vape
  • Exercise daily
  • Avoid eating animal meat daily. Substitute plant proteins like beans, lentils, nuts, and seeds often.
  • Limit salt to 2300mg a day. The easiest way to do this is to avoid processed foods.
  • Avoid large amounts of caffeine (<400mg a day)


Is drinking milk, plant milk, or fortified juice the best way to get all my calcium? NO. While it’s OK for babies and toddlers to drink most of their calories, school-aged children, teens, and adults should get the majority of their calories from solid foods. When you drink your calories, it’s too easy to overeat, and drinking juice or sweetened plant milk can cause dramatic shifts in your blood sugar. Try to limit your liquid food sources to one a day. It’s better to get your calcium from a variety of foods. A combination of organic cheese, organic unsweetened yogurt, high-calcium vegetables, fruit, nuts, seeds, fortified foods, and supplements is ideal. (Cheese and yogurt with live cultures have less lactose than milk. One or two servings of yogurt or cheese per day are tolerated by most people unless they are severely lactose intolerant or allergic to dairy.) Cheese and whole yogurt are high in saturated fat, so limit these foods to one or two a day. Get the rest of your calcium from other foods or supplements.

If I get enough Calcium and Vitamin D in my diet, do I need to bother getting daily exercise or eating vegetables to build strong bones? YES. It would be very difficult to absorb enough calcium and direct it to your bones without a healthy gut. It’s still important to make exercise and plenty of produce part of your daily routine and limit processed food, smoking, caffeine, meat intake, excess salt, and alcohol.

Is it possible to take too much Calcium? Yes. The upper limit for safety is 3000mg for teens and 2000mg for adults. That’s just over twice the RDA. It would be hard to get that much from food alone (unless you drink 7 servings of milk a day— don’t do that.). However, supplements plus food intake can really add up. Consider that antacids, like Tums ultra, contain 400mg of calcium per tablet— that means 1200mg per dose. Too much calcium can cause nausea, vomiting, constipation, gas, metabolic disturbances, or kidney stones, as well as zinc, magnesium, or iron deficiency.  Calcium supplements are sometimes contaminated with lead. Check the brand you’ve chosen with an independent lab like before taking them.

How much Calcium can you take at one time? You can’t absorb more than about 500mg at a time. Calcium supplements should have about 500mg per dose and should be taken with Vitamin D, 400-1000IU a day. If you need more than 500mg of calcium from supplements, divide your calcium into 2 doses a day

This information is general advice intended for those 12 and older. Consult your doctor to determine what is right for you.

2 thoughts on “The Brittle Relationship Between Calcium, Your Bones, and Your Microbiome.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: