How to get enough calcium on a dairy free diet

How to get enough calcium on a dairy free diet

Above: Chinese cabbage. A source of very bioavailable calcium.

Two common concerns I hear from people who need or choose to be dairy free are don’t I need dairy for healthy bones? (see my last blog post for the answer), and how to I get enough calcium in my diet?  

It’s definitely possible to get enough calcium without eating dairy. It’s not only about the amount of calcium that’s in the foods we eat.  There are some things that help us to absorb calcium properly, and some things that make us lose calcium faster from our bodies.  I’ll give you the low down on how to make the most of the calcium from your diet.

How much calcium do we need?

The recommended dietary calcium intake, according to the Australian Government National Health and Medical Research Council are as follows:

Babies 0–6 months approx. 210 mg (if breastfed)approx. 350 mg (if formula fed)
Babies 7–12 months 270 mg
Children 1–3 years 500 mg
Children 4–8 years 700 mg
Children 9–11 years 1,000 mg
Adolescents 12–18 years (including pregnant and breastfeeding young women) 1,300 mg
Women 19–50 (including pregnant and breastfeeding women) 1,000 mg
Women 51–70 1,300 mg
Men 19–70 1,000 mg
Adults over 70 1,300 mg

Ok, let’s take a look at the things that affect the amount of calcium that is available to be absorbed from food, how well it is absorbed and how quickly it is lost from our bodies.

Things that help calcium absorption

  • Good levels of vitamin D.  Vitamin D regulates calcium absorption in the gut.
  • Getting enough protein in the diet.
  • Good oestrogen levels in females and testosterone levels in men.
  • Good production of stomach acid.  It makes the calcium soluble for absorption.
  • Pregnancy and growth. Higher amounts of calcium are needed in pregnancy and breastfeeding.  By the time they are born, babies have been given 25-30g of calcium from their mothers.  As you can see from the requirement chart above, pregnant and breastfeeding women don’t require more calcium than pre-pregnancy.  This is because absorption of calcium in the gut doubles by the time a woman is 12 weeks pregnant.  Our bodies are clever!  Infants, who are growing very quickly, also have double the calcium absorption ability that an adult has.

Calcium robbers

Some things cause calcium to be excreted quickly from the body.  These include:

  • Caffeine.  Moderate amounts are fine as long as there is enough calcium intake.
  • Sodium.  High amounts of sodium cause more calcium to be lost in urine.
  • Smoking.  It prevents proper absorption of calcium in the gut.
  • Poor absorption of fats (such as in coeliac disease, use of slimming pills, some parasite infections) because unabsorbed fats can bind to calcium and stop absorption.  It also affects vitamin D absorption.
  • Acid lowering medications (such as proton pump inhibitors) and stress can alter good stomach acid needed for good absorption.
  • Taking magnesium and zinc supplements with calcium supplements or high calcium meals. They inhibit calcium absorption.
  • Phytates (phytic acid) found in whole grains, seeds and legumes bind to calcium and decreases its availability.  Phytic acid can be reduced by soaking, sprouting and fermenting these foods.
  • Oxalates, found in some plant foods.  Oxalates bind to calcium in the gut and prevents it from being absorbed.  Spinach is a good example that is often quoted as a good source of calcium.  Although one cup spinach contains 250mg of calcium (almost as much as a cup of milk), it’s high oxalate content means that only 5% of calcium is actually able to be absorbed.  You will need to eat more than 8 cups of spinach to get the same amount of absorbable calcium as one glass of cow’s milk.  Kale, on the other hand, is very low in oxalates and nearly 50% of the calcium is absorbed.  One and a half cups of kale gives the same amount of absorbable calcium as one glass of milk.  

Other high oxalate foods are include:

    • Veggies – rhubarb, swiss chard, beets, celery, eggplant
    • Fruit- currants, strawberries, blackberries, blueberries, gooseberries
    • Nuts – pecans, peanuts
    • Other – tea, cocoa

The plant foods I have included on the chart below are low in oxalates and better absorbed.

Good (bioavailable) sources of calcium

Food Amount of calcium Percentage of calcium absorbed
1 cup dairy milk (for comparison) 300mg 32%
Fortified dairy free milk 300mg 30%
Salmon 181mg 23%
Sardines (4) 180 mg 30%
Broccoli (1/2 cup) 35mg 53%
Kale (1/2 cup) 65mg 47%
Chinese mustard greens (½ cup) 212mg 40%
Chinese cabbage (½ cup) 79mg 54%
Turnip greens (½ cup) 99mg 52%
Tofu (½ cup) 258mg 31%
Pinto beans (½ cup) 45mg 17%
Red beans (½ cup) 40mg 17%
White beans (1/2 cup) 113mg 17%
Bok choy (½ cup) 78mg 54%
Sweet potato (½ cup) 44mg 22%
Unhulled tahini (1 Tbs) 88mg 20%
Almonds (¼ cup) 80mg 21%
Blackstrap molasses (1 Tbs) 145mg more than 50%

To investigate the calcium content of other foods that you eat, type them in to http://nutritiondata.self.com/

References:

Gropper SS, Smith JL. Advanced Nutrition and Human Metabolism. Cengage Learning; 2012. 606 p.

Malde MK, Bügel S, Kristensen M, Malde K, Graff IE, Pedersen JI. Calcium from salmon and cod bone is well absorbed in young healthy men: a double-blinded randomised crossover design. Nutr Metab (Lond). 2010 Jul 20;7:61.

Weaver CM, Proulx WR, Heaney R. Choices for achieving adequate dietary calcium with a vegetarian diet. Am J Clin Nutr. 1999 Sep 1;70(3):543s – 548s.

Weaver CM, Plawecki KL. Dietary calcium: adequacy of a vegetarian diet. Am J Clin Nutr. 1994 May 1;59(5):1238S – 1241S.



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