Of all of the minerals in our bodies, calcium is the most abundant. 99% of the body’s calcium supply is stored in our bones and teeth where it acts to support their structures and basic function. The remaining 1% is found in blood and other tissues where it’s hard at work ensuring our muscles can function (and remember, your heart is a muscle). It also plays a role in regulating proper blood flow throughout our bodies, communication between our cells, hormone secretion, and nerve transmission.
Because it is so important for vital body functions, our clever bodies very carefully regulate the amount of calcium present in our bloodstream, so it doesn’t fluctuate with dietary intake. The body uses bone tissue as a reserve in order to maintain constant concentrations of calcium in our blood, muscles, and intracellular fluids. Our bones are in a constant state of remodeling, with resorption of calcium from the bones into the bloodstream, and deposition of calcium from the bloodstream into new bone.
Pretty cool stuff, eh? But in spite of our body’s finely tuned calcium regulation, we still need to ensure adequate intake of dietary calcium in order to keep that system running smoothly.
When we’re young and growing, bone formation exceeds resorption. In the stages of early and middle adulthood, the processes are more or less equal, and in aging adults, especially among postmenopausal women, bone breakdown exceeds formation, thus frail and brittle bones become an issue with this age group.
How much calcium do we need?
Adults need to consume about 1,000mg of calcium per day. This increases to 1,200mg per day for women over 50, when bone loss starts to accelerate.
Vegans and vegetarians need to pay extra attention to their calcium intake, as they may not get enough calcium in their regular diets, or may not absorb it well. The same is true of those with conditions that cause compromised gut function, such as celiac or Chrohn’s disease or IBS, as well as athletes, and women over 50.
Where can you find plant-based calcium to incorporate into your diet?
A big old glass of milk, right? While it’s true that milk and other dairy products do contain a good amount of calcium, there is considerable debate amongst the scientific community about whether dairy is actually a healthy source of calcium. But the good news is that vegans, vegetarians, and lactose intolerants have plenty of options for plant-based ways to get it.
Good sources of plant-based calcium include:
- Leafy greens such as:
- spinach (136mg per 1 cup cooked)
- kale (172mg per 1 cup cooked)
- bok choy (158mg per 1 cup cooked)
- collard greens (268mg per 1 cup cooked)
- Tofu (varies by brand and firmness, but roughly 350mg per 100g of firm tofu)
- Tempeh (roughly 111mg per 100g)
- Beans such as:
- navy beans (62mg per half cup cooked)
- chickpeas (105mg per half cup cooked)
- pinto beans (109mg per half cup cooked)
- Almonds (75mg per ounce – about 25 almonds)
- Sesame seeds (88mg per tablespoon)
- Tahini (64mg per tablespoon)
- Blackstrap molasses (41mg per tablespoon)
- Dried figs (26mg per 100g dried figs)
- Rhubarb (105mg in 1 cup diced rhubarb)
- Chia seeds (65mg per tablespoon)
In addition to being a good source of calcium, leafy greens are also rich in oxalic acid, which binds with calcium and reduces absorption in the body. Cooking the greens will minimize the oxalate content, however, which is why we’ve provided the calcium content for cooked greens. If you’re a fan of green smoothies, consider lightly steaming your kale before adding it to the blender to unlock the full nutrient potential.
Eating plant-based calcium-rich foods together with vitamin D and magnesium-rich foods will help your body to absorb the calcium more easily. On the flip side, iron and zinc both compete with calcium absorption, so supplements or foods especially rich in these minerals should be avoided at the same time as calcium.
Kale image via Shutterstock.