Calcium is most commonly associated with the formation and metabolism of bone. Over 99 percent of total body calcium is found as calcium hydroxyapatite in bones and teeth, where it provides hard tissue with its strength.
The amount of daily recommended intake of the European Union is 800 mg / day.
It usually varies according to age for calcium intake. Pregnant women need to take high calcium to maintain baby growth and also calcium used in their bones and teeth.
Daily calcium intake should not exceed 1500 mg / day. because 2500 mg / day toxicity (poisoning) symptoms may occur.
Today most vegans try to get enough calcium from salads or tofu. But salad greens and spinach actually aren’t very good calcium sources, and spinach in particular is high in oxalates, which can block the absorption of calcium in food.
Every sort of leafy green contains a substantial amount of calcium. But there’s an important caveat to keep in mind: several popular greens contain substantial amounts of oxalates (oxalic acid).Oxalic acid hinders calcium absorption.
Oxalates won’t cancel out all the calcium your greens contain, but they can prevent you from absorbing most of it. Spinach is naturally high in calcium, but it is also high in oxalic acid. The body is unable to process the calcium it provides.
You may be suffering from severe fatigue due to a high consumption of oxalate foods, if you are following a gluten free diet.
A gluten-free diet is recommended for people with celiac disease, gluten-sensitivity or the skin disorder dermatitis herpetiformis. A gluten-free diet may be helpful for some people with irritable bowel syndrome, the neurological disorder gluten ataxia, type 1 diabetes and HIV-associated enteropathy. But not everyone. There is no one type diet that good for all.
| Carob powder | 2 tbsp | 42 mg |
| Poppy Seeds | 1 tbsp | 126 mg |
| Raw Lentils | 80 g | 140 mg |
| Orange | 150g | 60 mg |
| Rhubarb | 120 g | 103 mg |
| Figs dried | 60 g | 96 mg |
| Collard greens, cooked | 1 cup | 268 mg |
| Turnip greens, cooked | 1 cup | 197 mg |
| Tempeh | 1 cup | 184 mg |
| Kale, cooked | 1 cup | 177 mg |
| Soybeans, cooked | 1 cup | 175 mg |
| Mustard greens, cooked | 1 cup | 165 mg |
| Bok choy, cooked | 1 cup | 158 mg |
| Tahini | 2 tbsp | 128 mg |
| Wakame | 100 g | 150 mg |
| Okra, cooked | 1 cup | 124 mg |
| Almond | 30 g | 75 mg |
| Almonds, whole | 1/4 cup | 94 mg |
| Broccoli, cooked | 1 cup | 62 mg |
Note: Oxalic acid, which is found in spinach, rhubarb, chard, and beet greens binds with the calcium in those foods and reduces its absorption. These foods should not be considered good sources of calcium. Calcium in other green vegetables is well absorbed. Dietary fiber has little effect on calcium absorption.
How to avoid oxalic acid and how to increase your calcium absorbation?
Oxalic acid is easily reduced by steaming, boiling, or wilting the leaves of any of these vegetables for 5 to 6 minutes. Gently squeeze out any remaining water from the vegetables, and continue on with your favorite recipes
Coffee, tea and soft drinks such as soda contain caffeine, which may decrease calcium absorption and contribute to bone loss.
To maximize your absorption of calcium, take no more than 500 mg at a time.
Eating foods that have a lot of salt (sodium) causes your body to lose calcium and can lead to bone loss. Try to limit the amount of processed foods, canned foods and salt added to the foods you eat each day.
References:
https://www.nap.edu/read/13050/chapter/4#36
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5684325/
https://www.iofbonehealth.org/calcium-calculator
https://nutritiondata.self.com/facts/spices-and-herbs/203/2
https://pubmed.ncbi.nlm.nih.gov/3681480/
http://apjcn.nhri.org.tw/server/apjcn/8/1/64.pdf