Calcium is the most abundant material in the body. The body stores over 99% of the calcium in bones and teeth. The rest is found in nerve cells, body tissues, blood, and other body fluids. The body uses bones as a reservoir for (and sometimes source of) calcium. A proper level of calcium in the body over a lifetime can help prevent osteoporosis.
When you don’t get enough calcium, you also increase your risk of developing other conditions like:
- Osteopenia
- Calcium deficiency disease (hypocalcemia)
Importance of Calcium
Other than its vital role in the formation and strengthening of bones and teeth, calcium also helps with the following:
- Muscle contractions
- Normal enzyme functioning
- Clotting blood
- Sending and receiving nerve signals
- Squeezing and relaxing muscles
- Releasing hormones and other chemicals
- Maintaining a normal heart rhythm
The Evolutionary Perspective of Calcium
The present nutritional requirements of calcium is a result of a 200 million year evolution. The evidence indicates that this evolution occurred in a high-calcium nutritional environment.
Humans who lived during the Stone Age period consumed a lot more calcium (1500mg/day or even more) than we do today. The higher calcium consumption can be attributed to the requirement for higher physical exertion. Examination of bony remains from that period revealed a higher bone mass and lesser age-related bone loss.
While the Americans today get the majority of calcium through dairy foods, the stone age people had to rely on plant sources as domestication hadn’t begun by then. Their diet was also high in protein, fiber, and other micronutrients, and at the same time, low in sodium and fats. Archaeological evidence suggests that the Stone Age diet helped prevent diseases like heart disease, stroke, osteoporosis, and other chronic diseases.
Evolution has programmed our genes to adapt to a certain kind of nutritional pattern- which has many positive implications on our health. Changing our diet to match this ‘designated’ nutritional pattern can be a big challenge but can help achieve major improvements in our health.
RDA of Calcium
The RDA of calcium for adults 19-50 years of age is 1000 mg for both men and women. Women who are 51 and older (post-menopausal) and men who are 71 and older require about 1200 mg of calcium.
However, the WHO states that adults require only 500 mg of calcium per day.
How Genes Influence Calcium Requirements?
CASR Gene and Calcium Needs
The Calcium sensing receptor (CASR) gene encodes a calcium-sensing receptor, which binds to calcium present in the blood. The [CASR protein}(https://medlineplus.gov/genetics/gene/casr/) is present on the cells of the parathyroid glands and is associated with the secretion of the parathyroid hormone. This hormone transfers calcium from the bone into the blood, with bones acting as storage centers for calcium.
When calcium levels are high, the levels of parathyroid hormone are low. This facilitates increased binding of calcium to CASR receptors in the kidney. This ultimately leads to more removal of calcium via kidneys.
rs1801725 of CASR Gene And Calcium Deficiency Risk
rs1801725 is an SNP in the CASR gene associated with serum calcium levels. This SNP is also called A986S. It contributes to 1.26% of the variance in serum calcium levels. The T allele of rs1801725 was associated with higher serum calcium.
rs17251221 of CASR Gene And Calcium Deficiency Risk
Previous studies have indicated that rs17251221 in the CASR gene is associated with total serum calcium levels. People with the GG + GA genotypes have higher calcium levels than those with the AA genotype.
GATA3 Gene and Calcium Needs
GATA3, or GATA binding protein 3, is a gene that is located on chromosome 10 and belongs to the GATA family of transcription factors.
Defects in this gene have been associated with hypoparathyroidism.
Hypothyroidism causes a reduction in the calcium levels in the blood, i.e., hypocalcemia.
rs10491003 of GATA3 Gene And Calcium Deficiency Risk
rs10491003 is an SNP in the GATA3 gene. It is implicated in disorders of calcium imbalance. The T allele has been associated with a 0.027 unit increase in calcium levels.
CYP24A1 Gene and Calcium Needs
The CYP24A1 gene is located on chromosome 20 and encodes the enzyme 24-hydroxylase.
This enzyme is responsible for controlling the amount of active vitamin D available in the body.
Vitamin D is absolutely essential for the proper absorption of calcium from the intestines and is also involved in various processes required for bone and tooth formation.
Many mutations in this gene are found to be associated with idiopathic infantile hypercalcemia 1.
rs1570669 of CYP24A1 Gene And Calcium Deficiency Risk
rs1570669 is an SNP in the CYP24A1 gene. The A allele in this SNP is associated with a 0.012-0.024 decrease in the serum calcium levels. People with the AA genotype are at a higher risk for calcium deficiency.
Other genes like CARS, DGKD, DGKH, GGCKR, TTC39B, and WDR81 also influence calcium levels in the body.
Non-genetic Factors That Influence Calcium Requirements
Factors That Lower Calcium Levels
- Hormonal changes in women
- Dietary insufficiency
- Low levels of vitamin D
- Certain medications that influence calcium absorption
- Decreased phosphate and magnesium levels (hypophosphatemia and hypomagnesemia)
- Chemotherapy drugs
- Pancreatitis
- Parathyroidectomy - Removal of the parathyroid gland
Causes Of Increased Calcium Levels
Overactivation of parathyroid hormone: Also called hyperparathyroidism, this condition results in excess parathyroid hormone. This results in a calcium imbalance.
Medications: Diuretics release a lot of water from the body, which results in the underexcretion of calcium. Lithium causes excess secretion of the parathyroid hormone.
Lung diseases: Certain lung diseases like sarcoidosis result in high vitamin levels, which increases the level of calcium.
Cancer: Some cancers, especially lung, blood, and breast, increases your risk for calcium buildup.
Dehydration: This, coupled with poor kidney function, can increase your calcium levels.
Symptoms of Calcium Deficiency
Also called hypocalcemia, calcium deficiency is a condition where there are low calcium levels in the body. Women are more prone to calcium deficiency, especially those who are going through menopause. This is because of the decrease in the female hormone estrogen, which plays a vital role in calcium metabolism.
Some symptoms of hypocalcemia include:
-Muscle problems such as aches, spasms, cramps
-Increased numbness and tingling in the arms, legs, hands, and feet
-Severe fatigue, lack of energy
-Dry skin
-Weak and brittle nails
-Osteoporosis, that increases the chances of breaking or brittle bones
-Dental problems like poor oral health, week roots of teeth, brittle teeth, gum irritation, increased cavities
-Depression
-Hallucinations
Symptoms of Excess Calcium
Hypercalcemia/excess calcium describes a condition where there are high concentrations of calcium in the blood. This can be harmful to your bones and organs, especially to your kidneys.
The parathyroid hormone controls the levels of calcium in the body. Hypercalcemia is usually the effect of overactive parathyroid glands that result in an increase in the blood calcium levels.
Hypercalcemia affects different organs differently:
Kidneys: Kidneys need to overwork to filter all the extra calcium. This causes increased thirst and frequent urination
Bones: The calcium in the bone is leached out into the blood - thus, it gets weakened, which results in bone pain
Abdomen: Symptoms related to the abdomen include nausea, constipation, vomiting, and abdominal pain
Heart: High calcium levels can result in abnormal heart rhythms
Muscles: Hypercalcaemia can cause muscle weakness and spasms
Brain: Symptoms like lethargy, confusion, fatigue, and even depression
Dietary Recommendation for Calcium
One of the best ways to ensure healthy and optimum calcium levels is by sufficient dietary intake of the mineral.
Animal Sources of Calcium
- Dairy products
- Sardines
- Canned salmons
- Crabs
- Oysters
- Mussels
- Chicken
Plant Sources of Calcium
- Seeds - sesame seeds, poppy seeds, and chia seeds
- Greens: Leafy greens, Brussel sprouts
- Almonds
- Beans and Lentils
- Soya and Soya products
Summary
- Calcium is a mineral that is vital for the health of bones and teeth. Adequate calcium levels are very important to prevent osteoporosis, a condition where the bones become brittle and weak.
- Women require more calcium than men. The requirements also increase with age. Older people require more calcium in order to maintain their bone health.
- Certain genes regulate serum calcium levels. They do so by modifying the calcium receptors, vitamin D, and parathyroid hormone levels. Some examples of genes influencing calcium levels include CASR, GATA3, and CYP24A1. SNPs in these genes can increase or decrease the calcium levels in your body.
- Both excess (hypercalcemia) and low (hypocalcemia) levels of calcium are harmful. Hypocalcemia can result in muscle pain, fatigue, dry skin, depression, and brittle bones, while hypercalcemia can affect various organs like the kidney, brain, and heart.
- Sufficient dietary intake can help prevent calcium deficiency. Dairy products, sardines, chicken, seeds, and leafy greens are some good sources of calcium.
Reference
https://www.health.harvard.edu/staying-healthy/how-much-calcium-do-you-really-need
https://medlineplus.gov/genetics/gene/casr/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2908705/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3778004/
https://medlineplus.gov/genetics/gene/cyp24a1/#conditions
https://en.wikipedia.org/wiki/Parathyroid_hormone
