Calcium: health benefits, foods and deficiency
We all know that we need calcium for healthy bones and teeth, but many still believe that we need cow’s milk and dairy products to get it. Do vegans fall short of this essential mineral?
We associate calcium with bones and rightly so, but this important mineral has other functions, too. It is important for muscle function, nerve transmission, signalling within cells and hormone formation.
We are plagued by the myth that cow’s milk is essential for strong, healthy bones and teeth. If you look at the rates of osteoporosis around the world it becomes apparent that some aspects of the typical Western lifestyle are contributing to bone loss in addition to other so-called Western diseases such as diabetes and heart disease. It seems that the more dairy people consume, the higher their risk of fractures. Cow’s milk and dairy products do not protect us and they may actually be increasing the risk of fragile bones.
The acid-alkaline hypothesis
One of the suspected reasons is the ‘acid-alkaline hypothesis’ which suggests that as food is digested, acids are released into the blood and the body tries to neutralise this acid by drawing calcium from the bones. Animal proteins from cow’s milk and dairy products, meat, fish and eggs, are said to have a particularly bad acidifying effect because of the greater amount of sulphur-containing amino acids their protein contains compared to most plant proteins.
The calcium paradox
While the theory itself is scorned by some scientists, others acknowledge this detrimental effect of animal protein on calcium stores. The World Health Organisation called it the ‘calcium paradox’ whereby hip fracture rates are higher in developed countries where calcium intake is higher, than in developing countries where the intake is lower. They say evidence points to the adverse effect of animal (but not vegetable) protein. It follows that you’re better off getting your calcium from the wide range of healthier plant sources available, including green leafy vegetables, pulses (peas, beans and lentils), nuts and seeds.
Signs of deficiency include: muscle spasms or cramps, confusion, fainting, numbness and tingling in hands, feet and face, brittle nails, fragile bones, tooth decay and tiredness.
But back to bones – calcium is the building block for bones and your bones and teeth contain 99 per cent of all the calcium in your body. But calcium can only build bones properly if your body has enough vitamin D, because this helps calcium absorption. Even if you eat plenty of calcium, it could go to waste if you’re not getting enough vitamin D. In spring and summer, most people in the UK get enough through the action of sunlight on the skin, but in the winter months a supplement is needed.
Our bodies continually remove small amounts of calcium from our bones (resorption) and replace it with new calcium (ossification) and because of this constant bone remodelling, we need a regular, but not excessive, supply of calcium.
High intakes from dairy products and supplements can increase the risk of fractures and some excess calcium may be deposited in other tissues, such as kidneys, which can eventually cause problems such as kidney stones. Official guidelines say that adults need around 700 milligrams of calcium per day. Once intake surpasses 2,000 milligrams, the risk of harm increases. Taking more than 1,500mg a day could lead to stomach pain and diarrhoea.
How much are we getting?
The 2017 National Diet and Nutrition Survey in the UK found that overall, average daily intakes of calcium from food were above the recommended level for most people except teenagers and some women. In the 11-18 age group, almost one in five girls and 12 per cent of boys had low intakes along with eight per cent of women aged 19 to 64.
The best food sources
You should be able to get all the calcium you need from a healthy, vegan diet with no need for supplements. The best plant sources include tofu (made with calcium sulphate), fortified vegan breakfast cereals (Ready Brek), plant-based milk alternatives fortified with calcium, dried figs, kale, sesame seeds and tahini (sesame seed paste), tempeh (fermented soya beans), wholemeal bread, baked beans, butternut squash, almonds and Brazil nuts, spring greens and watercress.
Spinach, chard and beet greens contains relatively high amounts of calcium but also contain a substance called oxalate, which hinders absorption. It’s is better to get your calcium from green vegetables such as kale, broccoli and bok choy. The calcium in these is absorbed around twice as well as the calcium in cow’s milk. They also contain fibre, folate, iron and antioxidants – nutrients lacking in dairy.
Dairy products are not essential for good bone health, in fact they may harm it. A varied, vegan diet rich in vegetables, fruits, pulses, wholegrains, nuts and seeds provides plenty of calcium. Other ways to improve your bone health include not smoking or drinking, cutting down on tea and coffee as caffeine slows absorption, reducing your salt intake, exposing yourself to sunlight (but avoid burning) and ensuring you have fortified foods such as soya milk and margarine. Lastly, take physical exercise – this is perhaps the most important protective factor for bones. Use ‘em or lose ‘em!