The most abundant mineral in the human body is calcium.
Animal Foods high in calcium are:
Dairy foods, such as milk and milk products from cow and goat’s milk, such cheeses, yoghurt and butter. Fish that are canned are especially high in calcium as they are eaten with their bones. Salmon, sardines and whitebait are the most calcium-rich.
The food group with the highest content of calcium is seaweeds, and among them, the top scorer is wakame, with 1,300mg of calcium per 100g. Arame and kelp also score high with 1,170 and 1,093 mg of calcium per 100 g respectively. Dark green leaf vegetables, especially cabbage, watercress, mustard greens, dandelion and collard greens, as well as broccoli, turnip tops and asparagus; dried peas and beans, such as black-eyed beans and soy beans, nuts such as hazels and almonds; also organic unsulphurated blackstrap molasses, brewer’s yeast (Marmite) and curry powder are all significantly high in calcium.
What nutrients and factors enhance the body’s ability to absorb calcium?
The amino acid lysine is necessary for calcium absorption. Lysine is found in meat, dairy (milk and egg) products, soy and lima beans, as well as nuts, especially walnuts.
Oestrogen enhances the bones’ ability to absorb calcium, so phytoestrogen-rich foods, such as grains, coffee, beer and bourbon, help to keep calcium levels in bone high, for men and women. Moderate, load-bearing exercise, such as lifting weights and yoga, also help to enhance calcium levels as it is thought that calcium is laid down in the bones as the body reacts to gravity.
Vitamin D assists in the absorption of calcium.
What impedes calcium’s absorption?
A high intake of magnesium impedes the absorption of calcium, as these two mineral compete for absorption pathways. What that means is that if you have a lot of one in your diet, you have significantly less of the other. Because both calcium and magnesium are equally important to bone density and joint health, if you over-supplement with calcium your bone density will suffer and you will experience fractures and breaks. Nowadays, we are finding more and more evidence that calcium supplementation, that doctors have been offering peri and post-menopausal women for decades, not only has very little positive impact on bone health in women in later years, it actually has a harmful effect. It’s significant that doctors don’t actually study nutrition during the 7 years of their training, so one wonders where they get their nutritional information from.
Even though moderate exercise enhances calcium’s absorption into the body, heavy exercise impedes it. People with sedentary lifestyles also do not lay down enough calcium in their bones; the calcium is leached from their bones to be deposited in their joints: older people and pregnant women, therefore, who have less energy than younger people, are particularly at risk. (Also lazy people like me!)
Oxalic acid is said to inhibit the absorption of calcium. This applies only to foods where the oxalic acid is bioavailable. Foods that contain significant amounts of bioavailable oxalic acid are: peanuts, pecans, spinach, rhubarb, dark chocolate, wheat bran, and beets (tops and root). However, the oxalic acid in the foods only inhibits calcium absorption from that food itself, not other items in the meal. For example, if you eat a spinach and goat’s cheese salad, you will still absorb calcium from the cheese, but not from the spinach. So people who are taking care of their bones would do well to steer clear of this last food group. Apart from dark chocolate, as we should all be eating more of that. See the Magnesium podcast on this site for more information.
Both iron and zinc inhibit calcium absorption, as do diets high in meat protein, fats and simple sugars. Ideally, iron and zinc should be eaten at different times from calcium, but realistically this might be difficult to manage. Phosphorous is another mineral that is essential to life, but in larger than normal quantities it inhibits the absorption of calcium. The ideal quantity is 2 : 1 calcium to phosphorous. A healthy, balanced diet that is low in processed food and excessive fat, that contains local, seasonal, organic produce, should give the correct ratio.
Junk foods and processed foods contain a lot of phosphates, which upset the calcium / phosphorous balance.
People who eat a lot of protein, for example people on the paleo diet, which is relatively higher in protein, need more calcium as protein cannot be stored in the body and is expelled along with calcium in the urine. Not only does this strain the kidneys but it can lead to a build up of uric acid crystals, which end up being deposited in joints. A sign that your kidneys are under stress is darkness or pouches under your eyes.
Read more about calcium, protein and bone health in my blog post Menopause – Like A Boss