Plant-Based Diets: Calcium Absorption Explained

Calcium is a mineral that is well-known for its role in bone health. It is also important for muscle contraction, blood pressure regulation, nerve transmission, and blood clotting. While dairy products are a source of calcium, it is also naturally present in an array of plant foods.

Plant-based sources of calcium include dark leafy vegetables like broccoli and kale, beans, soy products, nuts, seeds, certain grains, and calcium-fortified foods and drinks.

However, it is important to note that the absorption of calcium from plant-based sources may be affected by the presence of anti-nutritional factors, such as oxalates and phytates. For example, spinach, sweet potatoes, and legumes contain oxalic acid and phytates, which can bind to calcium and inhibit its absorption.

To enhance calcium absorption, it is recommended to increase vitamin D and C intake. Vitamin D helps the body absorb and process calcium, and it can be obtained through sun exposure or consumed through plant-based sources such as mushrooms exposed to light, fortified orange juice, and fortified plant milk.

Calcium is crucial for bone health and muscle function

Calcium is a mineral that is crucial for bone health and muscle function. Our bodies cannot produce calcium, so we need to obtain it from food and drink sources, as well as supplements when necessary. Calcium is essential for building and maintaining strong bones and teeth, and 99% of the body's calcium can be found in bones and teeth.

Bones are in a constant state of remodelling, with bone being broken down and reabsorbed, and new bone being deposited with calcium. Bone growth and density increase the most during childhood and adolescence, with more bone deposited than removed. Most people reach their peak bone mass by the age of 30, after which bone loss slightly outpaces bone growth.

Calcium is vital in slowing down the natural decline in bone density that occurs after our peak bone mass is reached. Ensuring adequate calcium intake through diet helps to prevent osteoporosis, a disease that makes bones weak and brittle, increasing the risk of fractures.

Calcium also plays a critical role in muscle contractions. It facilitates the interaction between actin and myosin, two protein structures, during muscle contractions. Calcium binds to troponin, a protein found on the actin filament, causing a position change in tropomyosin, another actin protein, exposing the sites on actin where myosin can attach for muscle contraction.

The recommended daily calcium intake varies depending on age and sex. For adults under 50, the recommended amount is 1000 mg, while for those over 50, it is 1200 mg.

Calcium can be obtained from various plant-based sources, including dark green vegetables such as spinach, chard, kale, and broccoli, as well as almonds, tofu, and calcium-fortified foods like plant-based milk, yogurt, and orange juice. While oxalates and phytates in some plant-based foods can interfere with calcium absorption, the benefits of these foods outweigh the small amount of calcium lost, and soaking or cooking these foods can help reduce their impact on absorption.

Plant-based diets can provide sufficient calcium

Calcium is an essential nutrient for the body, playing a key role in maintaining bone health, muscle function, nerve transmission, blood clotting, and hormone secretion. While dairy products are often considered the main source of calcium, a plant-based diet can also provide sufficient calcium to meet the body's needs. Here are some reasons why plant-based diets can provide enough calcium:

Variety of Plant-Based Sources

Firstly, there are numerous plant-based sources of calcium, including soybeans and soy products like tofu, tempeh, and natto, which are excellent sources of calcium and protein. Beans, peas, and lentils are also good sources, providing calcium along with fiber and other essential nutrients.

Fortified Foods and Drinks

Fortified foods and drinks are another way to increase calcium intake on a plant-based diet. Some examples include plant-based yogurts, cereals, plant milk, and orange juice. Soy milk, in particular, is a great alternative to cow's milk as it contains a similar amount of protein and is often fortified with calcium and vitamin D.

High Calcium Absorption from Plant Sources

The absorption rate of calcium from plant sources can be high, especially from dark green vegetables. Blanching, soaking, and sprouting are techniques that can be used to reduce oxalates and phytates in vegetables, which inhibit calcium absorption, thus increasing the bioavailability of calcium from plant-based sources.

Health Benefits of Plant-Based Calcium

Plant-based sources of calcium offer health benefits that dairy sources may not provide. Dairy products are a source of saturated fat, dietary cholesterol, sodium, and trans fats, which can have negative health impacts. Plant-based sources, on the other hand, provide a range of essential nutrients and can help lower LDL cholesterol and reduce the risk of type 2 diabetes, heart disease, and premature death.

Calcium Requirements Met by Plant-Based Diet

A well-balanced plant-based diet that includes a variety of vegetables, fruits, legumes, whole grains, nuts, and seeds can provide sufficient calcium to meet the body's requirements. The bioavailability of calcium from plant sources is often higher than that of dairy products, and the risk of health issues associated with dairy consumption is avoided.

In summary, a plant-based diet can indeed provide sufficient calcium to maintain healthy levels of this mineral in the body. By including a variety of plant-based sources, utilizing fortified foods and drinks, and ensuring adequate vitamin D intake, individuals can meet their calcium requirements while also enjoying the health benefits associated with plant-based diets.

Calcium absorption is affected by other nutrients

Calcium absorption is affected by the presence of other nutrients in the diet.

Calcium absorption is influenced by the amount of calcium ingested. At very low intakes, a fractional absorption of 100% is not achieved, and the decay in fractional absorption with increasing calcium intake is not linear but logarithmic. This means that while the percentage of absorbed calcium decreases, the amount of calcium absorbed increases with higher calcium intake.

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Calcium supplements may be unnecessary and harmful

Calcium is a mineral that is crucial for bone health, muscle function, and more. While calcium supplements are popular, studies suggest that some benefits are best gained from food sources such as dairy products and calcium-fortified foods rather than supplements.

The Problem with Calcium Supplements

Calcium supplements may not help your bones at all, and may even lead to major health problems. Multiple studies have found that there is little to no benefit to taking calcium supplements for the prevention of hip fractures. On the other hand, recent studies have linked calcium supplements to an increased risk of colon polyps and kidney stones. Additionally, a 2016 study suggested that calcium supplements may increase the risk of calcium buildup in the heart's arteries.

A Better Way to Get Calcium

Meeting your calcium needs through your diet is a safer alternative to supplements. When you get calcium through your diet, you're taking it in small amounts spread throughout the day, which helps your body absorb the nutrient. Most people can get adequate calcium through their diet if they make an effort. Good dietary sources of calcium include garbanzo, white and pinto beans, low-fat dairy, leafy green vegetables such as kale and spinach, and calcium-fortified foods.

Exercise to Strengthen Bones

Being active and exercising regularly also protects bone health. Weight-bearing exercises such as walking, jogging, and weight training are especially helpful in preventing bone loss. Simply moving more throughout the day supports bone health, too.

Plant-Based Calcium Sources

For those on plant-based diets, getting enough calcium is possible but it requires some planning. In a plant-based diet, calcium can be found in dark leafy vegetables like broccoli and kale, beans, soy products, nuts, seeds, certain grains, and calcium-fortified foods and drinks. If possible, the best way to receive calcium is from food sources. However, low-dose calcium supplements can be a helpful addition for those struggling to meet their needs.

Increasing Calcium Absorption

Calcium absorption is dependent on calcium bioavailability, which describes how well the body absorbs and uses nutrients. Dairy sources of calcium contain more calcium but may have a lower bioavailability (about 30%) than some plant sources of calcium, like bok choy, kale, and broccoli (about 50%). Vitamin D and Vitamin C also play a role in increasing calcium absorption.

Fortified foods can help meet calcium requirements

Fortified foods are those that have had calcium added during the manufacturing process. These foods can include plant-based yogurts, cereals, flour, cornmeal, and orange juice. Fortified drinks such as plant-based milk and orange juice can also add significant amounts of calcium to your diet.

For example, 1 cup (249 g) of fortified orange juice usually covers up to 28% of your daily calcium requirements. Similarly, soy milk is a great alternative to cow's milk, as it contains about the same quantity of protein.

However, it is important to note that not all plant-based milk is fortified, so it is important to check the label before buying. Additionally, it is recommended that at least half of your calcium intake comes from your diet, rather than supplements.

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