What’s required for our body to absorb Calcium? And what’s the link with Vitamin D?
Getting enough calcium in the diet is important for healthy bones and teeth, as well as helping regulate blood pressure, nerve function and muscle contraction. Too little calcium in the diet can lead to osteoporosis in later life, a chronic disease leading to weakening of the bones, resulting in bone fracture. Worldwide it is estimated that 1 in 3 women aged over 50 will experience osteoporotic fractures, while 1 in 5 men will be affected.
Adults need an estimated 700mg of calcium per day to help maintain the skeleton. This translates to one glass of milk (250mg), two sardines (91mg) and 100g of calcium set tofu (350mg) per day. The most recent National Diet and Nutrition Survey, which looks at dietary intakes of the UK population, showed that most adults were hitting the 700mg nutrient target. If you have coeliac disease, osteoporosis, are breastfeeding, or post-menopause you may need up to 1000mg or 1500mg. The British Dietetic Association have a useful tool for assessing how much calcium you get in your diet as well as tips and tricks to improve dietary intakes.
Dairy products are the most common food sources for dietary calcium requirements. The bioavailability in milk is 30-35%, which appears to be low. Relatively speaking, that is much higher in comparison to spinach, where only around 5% of calcium can be absorbed. This is due to some plants like spinach containing inhibitory substances such as oxalates and phytates, which compete with uptake, meaning you would need to consume eight times the amount of spinach compared to milk to achieve that same uptake of calcium.
Fish like sardines, pilchard, white bait are highest on the list with up to 400mg of calcium per 100g of fish, if you eat the bones, providing a higher content than milk. For people with lactose intolerance or dietary restrictions there are other good sources of calcium, for example green leafy vegetables (e.g kale, spring green, parsley), almonds, sesame seeds, and soya protein (firm tofu). It is always advised to have a wide variety of sources for our dietary intake. Further sources of this vital mineral can be found at the National Osteoporosis Society.
It is also important to point out that Vitamin D is required for the absorption of calcium, as well as aiding maintenance of bone health. See our recent blog on Vitamin D and the new government regulations due to latest research.
Combining dietary intakes of calcium with weight bearing exercise can also improve bone density, helping keep osteoporosis at bay. Weight bearing exercises include walking, running, boxing and high impact aerobics, and all help prevent bone loss by stimulating bone-strengthening processes.
If you are concerned about not achieving the right intake, speak to your GP or local pharmacist about supplementation.