How Calcium Is Absorbed and Utilized in Digestion
Calcium is a nutrient that is required by all living things, including humans. It is the body's most prevalent mineral and is essential for bone health. Humans require calcium to produce and maintain strong bones and it has been estimated that bones and teeth contain 99 percent of the body's calcium. It's also required for keeping the brain and other sections of the body in good working order. It helps with muscle activity and cardiovascular health. Many foods naturally contain calcium, and some food producers add it to their products. There are other supplements available.
Vitamin D, which helps with the digestion of calcium, is required in addition to calcium. Fish oil, fortified dairy products, and sun exposure are all good sources of vitamin D. Before moving on, let us take a brief look at the Human Digestive System.
Human Digestive System
The gastrointestinal tract, as well as the digestive organs that support it, make up the human digestive system (the tongue, liver, pancreas, salivary glands, and gallbladder). Food is broken down into smaller and smaller components during digestion until it could be taken and incorporated into the body. The cephalic phase, the stomach phase, and the intestine phase are the three stages of digestion.
Gastric secretions are produced in reaction to the sight and smell of food in the initial stage of digestion, known as the cephalic phase. The mechanical breakdown of food through chewing and the chemical breakdown of food via digestive enzymes both occurs in the mouth during this stage.
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Importance of Calcium in Body
Calcium has a variety of functions in the body. The following are some of them:
Bone Health
The bones and teeth contain nearly all of the calcium throughout the human body. Calcium is required for bone formation, growth, and maintenance.
Calcium aids in the growth of children's bones as they grow. Calcium managed to help strengthen bones and slow down bone density loss, which seems to be a natural part of the ageing process, even after a person has stopped growing.
Males and younger adults lose bone density at a faster pace than women who have previously gone through menopause. They are more likely to develop osteoporosis, and a doctor might advise calcium supplements.
Muscle Contraction
Calcium aids in the control of muscular contractions. The body produces calcium when a neuron stimulates a muscle. Calcium aids muscular contraction by assisting the proteins in the muscle.
The muscle relaxes as the calcium is pumped out of it by the body.
Cardiovascular System
Calcium is essential for blood coagulation. Clotting is a multi-step operation that requires a lot of patience. A variety of substances, including calcium, are involved.
Calcium's role in muscular function involves keeping the cardiac muscle in action. The smooth muscle which surrounds blood arteries relaxes when calcium is present. Several studies have found a correlation between high calcium consumption and decreased blood pressure.
Vitamin D is also important for bone health because it aids calcium absorption.
Other Roles
Many enzymes require calcium as a cofactor. Certain important enzymes cannot function properly without calcium.
Calcium deficiency has also been linked to the following outcomes in studies:
During pregnancy, there is a lesser risk of acquiring high blood pressure issues.
Young people's blood pressure stays lower.
Those whose mothers received enough calcium throughout pregnancy had reduced blood pressure.
cholesterol levels get improved.
colorectal adenomas, a form of non-cancerous growth, are less likely to occur.
Calcium-rich Foods
Sources of calcium may include:-
cheese, milk, and several other dairy foods
fish wherein one eat the bones – such as pilchards and sardines
soya drinks with added calcium
green leafy vegetables, including turnip leaves, okra, broccoli, curly kale, spinach and watercress
bread and anything that is prepared using fortified flour
many fortified breakfast cereals
legumes and grains
cornmeal and corn tortillas
nuts and seeds, particularly sesame, almonds, and chia
fortified fruit juices
Calcium Digestion
The circumstances in the small intestine lumen have an impact on calcium absorption. The calcium is converted to salt by the stomach's acid secretion, which is collected largely in the duodenum. Calcium that is not absorbed is precipitated within the ileum and eliminated in the stool. Excessive fatty acid and high amounts of magnesium and oxalates hinder calcium absorption, but lactose, the sugar in milk, improves it.
A process that demands energy absorbs calcium all across the brush boundary of the enterocyte cell membrane. Vitamin D is required for this activity, and when it is low, active calcium transport is halted. Calcium absorption is further influenced by parathyroid hormone (parathormone) and pituitary growth hormone. A typical meal comprises 1,200 mg of calcium, with about a third of it being absorbed. 99 percent of the calcium in the blood is reabsorbed when it passes through the kidneys. As a result, significant calcium losses occur in both kidney failure and malabsorption states. Calcium is reabsorbed from the bone in calcium shortage, weakening and softening the skeletal structure.
Calcium Deficiency
Low calcium levels, commonly known as hypokalemia, can be caused by the following conditions or lifestyle habits:
Bulimia, Anorexia, and a few other eating disorders
Overconsumption of Magnesium
Chelation Therapy Used For Metal Exposure
Mercury Exposure
Elongated Use of Laxatives
Prolonged Use of Few Medicines, Including Corticosteroids Or Chemotherapy
Lack Of Parathyroid Hormone
People who intake a lot of sodium or protein might face excretion of calcium.
High consumption of soda, caffeine, or alcohol
Various Cancers
Certain conditions, like Inflammatory Bowel Disease, Celiac Disease, Crohn’s Disease, and few other digestive diseases
Some surgical procedures, including removing the stomach
Vitamin D Deficiency
Kidney Failure
Phosphate Deficiency
Pancreatitis
Calcium is excreted by the body via urine, sweating, and faeces. Calcium levels in the body might be reduced by foods and activities that promote such functions.
Calcium Supplements:
Calcium supplements might be recommended by a doctor if you have a calcium shortage. The supplement users should do the following:
Check with their doctor to see whether they require supplements.
Follow the doctor's instructions for the dose.
Take the supplement with meals for optimal absorption and to reduce the risk of side effects.
The supplements should be taken at regular intervals, normally two or three times each day.
As per the ODS, approximately 43% among all adults in the United States, particularly 70% of older females, use calcium supplements. Consuming calcium supplements might boost daily calcium intake by roughly 300 mg on average.
Vitamin D is found in far too many calcium supplements. Vitamin D aids in the absorption of calcium and promotes protein synthesis in the body.
Types of Supplement
Supplements come in a variety of forms. A doctor can advise you on the best course of action. This will be determined by the individual's demands and preferences, as well as any medical problems and drugs they are taking.
Although elemental calcium is a pure mineral, it does coexist with various compounds in its natural state.
Calcium Carbonate: This is made up of 40% elemental calcium. This style is widely available, as well as inexpensive and convenient. It should have been taken with meals since stomach acid aids absorption.
Calcium Lactate: This comprises 13% elemental calcium.
Calcium gluconate: This comprises 9% elemental calcium.
Calcium Citrate: This has a calcium content of 21% elemental calcium. It can be taken with or without a meal. Achlorhydria, Inflammatory bowel disease, and various absorption diseases can all benefit from it.
Risks of Supplements
Supplement use has been linked to a variety of benefits and downsides, according to research. The majority of specialists think that getting nutrients through natural food sources is preferable, albeit this is not always achievable. Calcium supplementation, on the other hand, has been linked to health risks in several studies.
Side Effects:
When taking calcium supplements, some persons have gastrointestinal symptoms including bloating, gas, constipation, or a mixture of all three.
Calcium citrate, on the other hand, has fewer and milder adverse effects than calcium carbonate. Using the supplements alongside food or throughout the course of the day might assist in reducing the occurrence or severity of adverse effects.
Complications:
High consumption of calcium supplements may lead to:
kidney problems
kidney stones
calcification of soft tissues and blood vessels
constipation
As per the ODS, these serious adverse effects are more frequently the result of cancer and thyroid disorders than of excessive calcium levels caused by taking too many supplements.
FAQs on Calcium in the Human Digestive System: Role and Benefits
1. What is the primary role of calcium within the human digestive system?
In the digestive system, the primary role of calcium is not digestion itself, but rather its efficient absorption for use throughout the body. After ingestion, stomach acid helps to ionise calcium, making it soluble. The main absorption then occurs in the small intestine, particularly the duodenum and jejunum, from where it enters the bloodstream to perform its vital functions.
2. How is calcium from food absorbed in the small intestine?
Calcium is absorbed through two main pathways in the small intestine. The primary method is active transport, a process regulated by Vitamin D, which actively moves calcium through intestinal cells into the blood. The second is passive diffusion, where calcium moves between cells when its concentration in the intestine is very high. Active transport is the more efficient and regulated mechanism for meeting the body's needs.
3. What are some of the best dietary sources of calcium for students?
Students can get calcium from a variety of food sources. The most well-known are dairy products, but many other options exist. Key sources include:
- Dairy Products: Milk, yoghurt, and cheese are rich in highly absorbable calcium.
- Leafy Green Vegetables: Spinach, kale, and collard greens (though some, like spinach, contain oxalates which can reduce absorption).
- Fortified Foods: Many breakfast cereals, plant-based milks (soy, almond), and orange juices are fortified with calcium.
- Fish: Canned sardines and salmon, where the soft bones are eaten, are excellent sources.
- Other Sources: Ragi, tofu, and beans also contribute to daily calcium intake.
4. How does Vitamin D influence the absorption of calcium in the gut?
Vitamin D is crucial for calcium absorption. The body converts Vitamin D into its active form, calcitriol. This hormone then acts on the cells of the small intestine, prompting them to produce a special protein called calbindin. Calbindin binds to calcium ions and transports them across the intestinal cells into the bloodstream, significantly boosting the efficiency of the active transport mechanism.
5. What common dietary factors can inhibit or reduce calcium absorption?
Certain substances found naturally in foods, known as anti-nutrients, can interfere with calcium absorption. The two main inhibitors are:
- Oxalic Acid: Found in foods like spinach, rhubarb, and sweet potatoes. It binds with calcium to form insoluble calcium oxalate, which the body cannot absorb.
- Phytic Acid: Present in whole grains, seeds, nuts, and legumes. It can form insoluble complexes with calcium, reducing its bioavailability.
6. What is hypocalcemia and how does it relate to the digestive system?
Hypocalcemia is a medical condition characterised by abnormally low levels of calcium in the blood. It directly relates to the digestive system because its primary cause is often long-term insufficient dietary intake of calcium or poor absorption in the gut. Conditions like Vitamin D deficiency or digestive disorders can impair the intestine's ability to absorb calcium, leading to hypocalcemia and, over time, problems like osteoporosis (weak bones) and dental issues.
7. Can taking too much calcium from supplements cause digestive problems?
Yes, taking high doses of calcium, especially from supplements, can lead to digestive side effects. Calcium carbonate, a common form in supplements, can cause constipation, bloating, and flatulence. It acts as an antacid, and excessive amounts may interfere with the absorption of other essential minerals like iron and zinc in the digestive tract.
8. Apart from strong bones and teeth, what are other key functions of calcium that depend on its proper digestion and absorption?
While 99% of the body's calcium is in bones and teeth, the 1% in the bloodstream, absorbed via the digestive system, is vital for several functions, including:
- Muscle Contraction: Essential for all muscle movement, including the peristaltic waves that move food through the digestive tract.
- Nerve Impulse Transmission: Allows nerves to carry messages between the brain and the rest of the body.
- Blood Clotting: Plays a critical role as a cofactor in the coagulation cascade to prevent excessive bleeding.
- Hormone Secretion: Involved in the release of various hormones and enzymes.
9. Why is getting calcium from food sources often considered better than relying solely on supplements?
Calcium from dietary sources is generally preferred because the nutrients are consumed as part of a whole food matrix. For instance, dairy products also contain Vitamin D and lactose, which can enhance calcium absorption. Food provides a slower, more sustained release of calcium, which the body can process more effectively. Supplements, on the other hand, deliver a concentrated dose that can sometimes be incompletely absorbed and may lead to the digestive side effects mentioned earlier.
10. How do hormones regulate calcium levels in the blood after it is absorbed from the intestine?
The body maintains a tight control over blood calcium levels through a hormonal feedback loop. If levels drop, the parathyroid glands release Parathyroid Hormone (PTH). PTH increases calcium levels by stimulating its release from bones, reducing its excretion by the kidneys, and activating Vitamin D to boost intestinal absorption. Conversely, if calcium levels are too high, the thyroid gland releases calcitonin, which lowers blood calcium by promoting its deposition into bones and increasing its excretion.
