The review paper, published in the latest edition of the Open Heart journal, stated that the majority of the US population did not consume the current recommended dietary allowance for calcium.
This finding has also been echoed in Europe with studies identifying dietary calcium intake as low - 300 and 600 mg/day in women, and 350 and 700 mg/day in men.
“Calcium is ideally obtained from dietary sources. The form of calcium in bones and bone meal is calcium-hydroxyapatite, which may be particularly effective for building bone,” said Dr Hogne Vik, chief medical officer with NattoPharma.
“Increased consumption of calcium-rich foods such as bones, fermented dairy products (e.g. yogurt, kefir, cheese), leafy greens, almonds, and chia seeds may be effective for improving both skeletal and cardiovascular health.”
The review also found milk and dairy products the most readily available dietary sources of calcium that were preferred by the general population.
However, concerns as to these food’s long-term health effects were mentioned as milk, in particular was singled out as a promoter of inflammation and oxidation in adult humans.
Despite this, the review detailed a series of steps that could help in building strong bones while maintaining soft and supple arteries.
These included obtaining calcium from dietary sources rather and ensuring that adequate animal protein intake is coupled with calcium intake of 1000 mg/day.
Other measures included maintaining vitamin D levels in the normal range, and increasing intake of fruits and vegetables to alkalinise the system and promote bone health.
Other research has shown that calcium supplementation can play an important role in boosting levels, especially in areas where healthy diets are less common.
Recommended calcium intake in Europe
- The average calcium requirement for young adults (18–24 years) is 860 mg/day as defined by the European Food Safety Authority (EFSA).
- EFSA also define the safe upper limit for calcium intake in adults, including pregnant and lactating women, at 2,500 mg/day.
Milk is unhealthy?
The findings that suggest milk as a less-than-ideal source of calcium will come as a surprise to many.
Indeed, the review acknowledged that "cow's milk, though rich in many nutrients, including calcium, has issues that render it less than ideal as a dietary staple for many adults."
These issues include milk’s d-galactose content, which has been linked to a high mortality rate and high fracture incidence.
The European Dairy Association has recognised milk and dairy products as part of a healthy and balanced diet and an important provider of many minerals and vitamins and high quality protein.
The review, led by Dr James H O'Keefe of the Saint Luke's Mid America Heart Institute, discussed the fundamental role of calcium in cell conduction, muscle function, hormone regulation, and cardiac and blood vessel function.
Here more than 70 studies carried out over a 40-year period between 1978 to the present day, were assessed and evaluated.
These studies included observational, prospective cohort, double-blind placebo-controlled, and population-based research.
Along with calcium’s direct benefits the paper also recognised its role in facilitating vitamin K-dependent pathways.
Increased vitamin K2 intake has been associated with decreased arterial calcium deposition and the ability to reverse vascular calcification in animal models.
“While too much supplementary calcium has been cited as increasing cardiovascular risk, one cannot abandon an essential nutrient for building strong bones. The key here is Vitamin K2,” said Vik.
“Vitamin K2 (as MK-7) activates proteins already present in the body that help the body to properly utilise calcium. If we are balancing our calcium intake with Vitamin K2, we are simultaneously building strong, healthy bones while protecting our cardiovascular health.”
Vitamin K2 is abundantly found in meat, especially liver, chicken and beef along with dairy products. The primary vegetarian source is Nattō, a Japanese soybean food fermented with the bacterial species Bacillus subtilis var. natto.
“The only food that contains enough Vitamin K2 is the Japanese dish Natto,” explained Vik, whose company NattoPharma has responded to rising demand for vitamin K2-fortified supplements and foods in recent years.
Source: Open Heart
Published online ahead of print, doi:10.1136/openhrt-2015-000325
“Nutritional strategies for skeletal and cardiovascular health: hard bones, soft arteries, rather than vice versa.”
Authors: James O'Keefe et al.