Low calcium levels in the blood are known medically as hypocalcaemia. There are several hormones in the body which keep calcium levels tightly regulated, but changes in these levels can cause calcium levels to drop.
Surprisingly, hypocalcaemia is rarely due to a lack of calcium in the diet, although this can be a cause.
Calcium is a vitally important mineral in the body with 99% of it being found in our bones and the rest circulates in the blood.
Calcium And Bone Health
Getting the right amount of calcium in our diet is important for healthy bones.
On average, the adult skeleton contains 1200g of calcium which is present in the form hydroxyapatite, a crystalline structure made up of calcium and phosphorus. Calcium is needed for the mineralisation of bone. The rate at which calcium is deposited is directly proportional to the rate of growth. Therefore, it is essential that an adequate amount of calcium is ingested through the diet to ensuring peak bone mass is attained. If calcium ingestion is low it can lead to lower than normal bone mineral density which can lead to osteoporosis later in life.
What Causes Low Calcium?
Low calcium is when there are low levels of calcium in the blood. Around 50% of the calcium in the blood is free and active in the body, while the other half is known as inactive and is bound to proteins and other compounds. Therefore, the most common cause of low calcium levels in the blood is low protein levels, in particular, albumin.
Low Vitamin D
Parathyroid hormone and vitamin D both regulate the concentration of calcium in the blood. The parathyroid hormone stimulates the resorption of calcium in the kidney and the release of calcium from the bones. Parathyroid hormone is also responsible to produce the most active form of vitamin D, 1,25-dihydroxyvitamin D. It is produced from calcitriol (25-hydroxyvitamin D and works on the gastrointestinal tract to increase the absorption of calcium.
For the body to produce vitamin D, we must be exposed to the UVB rays of the sun. Therefore, if an individual’s sun exposure is low and their dietary intake is also reduced then hypocalcaemia can occur.
You can track your Vitamin D level through a simple at home finger prick blood test.
Low Parathyroid Hormone Levels
Hypocalcaemia occurs in people whose parathyroid glands are not functioning perfectly. The parathyroid glands are located near the thyroid gland in the neck. When these glands are impaired, they do not produce enough parathyroid hormone which causes blood calcium levels to drop.
Other causes of low calcium levels include:
- Reduced dietary intake of calcium
- Magnesium deficiency
- Acute inflammation of the pancreas
- Chronic kidney disease
- Bone disease
- Too much phosphate
What Are The Symptoms Of Low Calcium?
Many people don’t experience symptoms when their calcium levels are low. However, some of the symptoms associated with low calcium levels are:
- Muscles twitches
- Painful muscle spasms and cramps
- Numbness/tingling in feet, hands and/or mouth
- Dry skin
The normal functioning of our muscles and nerves is dependent upon extracellular calcium concentrations. For example, calcium is important for:
- Muscle contraction
- Nerve impulse transmission
- The expansion and contraction of blood vessels
- The production of hormones
- Strong teeth and bones
When our muscles contract, calcium ions are released by nerve endings. These ions bind to activator proteins which allow the muscle to contract. Without calcium or low calcium levels, the muscles can twitch or spasm, a process called neuromuscular irritability or excitability.
Good Sources Of Calcium
The best sources of calcium are dairy products. In the UK, milk and its associated products provide over 40% of the calcium intake in adults. Therefore, individuals who can’t or choose not to eat dairy are most at risk of calcium deficiency, so too are individuals who:
- Have osteoporosis
- Have coeliac disease
- Are breastfeeding
- Are past the menopause
Good sources of calcium are:
- Cow’s milk
- Fish with the bones
- Calcium-fortified milk substitutes
Other sources of calcium include plant foods such as soya beans. Soya beans are a good bioavailable source of calcium. The absorption of calcium can be affected by the presence of other compounds in food such as fat, protein and phosphorus. For example, spinach contains a high amount of calcium but is not considered a bioavailable source due to the presence of oxalic acid which prevents calcium absorption.
Vitamin D is important for the absorption of calcium from foods. You should aim to spend some time in the sunshine during the months of April to September. Going outside for 15 minutes, three times per week without wearing sunscreen between 11 am and 3 pm should be adequate. However, you may wish to consider a vitamin D supplement.
Some food sources of vitamin D include:
- Oily fish
- Fortified breakfast cereals, spreads and bread
We have a number of biomarker tests that are specifically tailored to check key biomarkers in your body including calcium, albumin and vitamin D:
This test measures and tracks 20 key biomarkers including energy, fat, sugar, stress, inflammation and bone health.
This nutritional health test will check vitamin levels and identify any deficiencies, so you can make the necessary adjustments to your diet or compensate with supplements where required.
If you are vegan this plant-based diet test helps you check that your body isn't missing vital nutrients.
British Dietetic Association. (2017). Calcium. Available at: https://www.bda.uk.com/uploads/assets/b1f5f83d-fdd0-41be-b7ef16c174fdcbc8/Calcium2017-food-fact-sheet.pdf
British Nutrition Foundation. (2005). Dietary Calcium and Health. Available at: https://www.nutrition.org.uk/attachments/205_Dietary%20calcium%20and%20health%20summary.pdf
Cooper, M, S and Gittoes, N, J, L. (2008). Diagnosis and Management of Hypocalcaemia. BMJ: 336, pp 1298-1302.
Lab Tests Online. (2019). Calcium Test. Available at: https://labtestsonline.org.uk/tests/calcium-test
Tai, V et al. (2015). Calcium Intake and Bone Mineral Density: Systematic Review and Meta-Analysis. BMJ: 351.