Should you take a calcium supplement, just in case?
Is it Safe to Supplement with Calcium? Please read on before you decide.
It’s not unusual for newspapers to sensationalise and misrepresent a rare issue. Such content reassures the mainstream readership that their omnivore diet, although contributory to climate change, animal exploitation and many of the leading causes of death, could be justified because it will spare them from osteoporosis or some other rare bone condition.
There are some many issues with this kind of journalism on so many levels. A study based on a sample of one is not very helpful. And, it’s not even a study. We don’t really know what the lady ate over those 10 years? A vegan diet can comprise chips and cola. How much alcohol did she consume? To what extent did she exercise – impact exercise is very beneficial for bone health? What was the state of her bone health before she became vegan? Did she have a genetic disorder? What was the state of her microbiome? Did she eat raw spinach daily causing phytate to act as an inhibitor? We also don’t know how many non-vegans also experienced the same rare bone condition. Those that did won’t make for interesting reading in the popular press.
It does appear that bone mass declines and the risk of fractures increases as people age, especially as women pass through the menopause.
Most people associate calcium with bones health. But you may be surprised to read that we’ve known for over 70 years that it’s a vital important mineral involved in muscle contraction and particularly important for heart health.
Malcolm’s Doctor’s complicity is understandable. Calcium is a surprisingly vital mineral for many body functions. Maintaining a constant plasma [Ca2+] is important for nerve transmission; muscle contraction; heart function; blood clotting; bone formation and body cell functions.
Before you start googling “calcium supplements”, remember there is a profitable industry that make and sell supplements. There are many misleading blogs out there making claims for this or that supplement some of which are funded from supplement adverts or even direct sales.
Computer vector created by upklyak
Malcolm’s doctor was not hesitant to prescribe a calcium supplement on the basis that that “an excess of calcium would not be harmful”. But is that correct? My favourite go-to source on nutrition research topics was clear that supplementing with calcium was associated with increased risk of heart attacks and strokes. And calcium supplementation can lead to kidney stones too. There is strong evidence through randomized controlled trials that calcium supplementation increases risks of all-cause mortality. What’s more there is insufficient evidence that calcium supplementation ensures good bone health .
There has also been concerns about lead contamination in calcium supplements. Only 10% of the calcium supplements analysed met the criteria of acceptable lead levels (1.5 μg/daily dose) in supplements/consumer products set by the United States.
Also of concern here is that an excess intake of calcium (via supplementation) was associated with increased risk for cancer death. But note this was a prospective cohort study (over time it follows a group of similar individuals to examine certain factors, to determine how these factors affect rates of a certain outcomes) and such studies are susceptible to confounding factors and not as conclusive as randomized controlled trials. So, this evidence should be regarded as weak.
From Where Do We Get Our Calcium?
So how much calcium do we get in our food and how much do we need? This is where it gets interesting. It seems that intake from food sources varies considerably from day to day and person to person. One study found that daily intakes of calcium ranged between 415 and 1740 mg. (Remember that 1,000 micrograms (mg) make one gram and 1,000 grams make a kilogram). That’s a wide range of dietary intakes. But the study also considered calcium excretion and what that showed is that a healthy body seems to regulate our calcium balance. If your dietary intake is on the low side, you excrete less and absorb more. If your intake is to high your body absorbs less. It seems that 741mgs daily is about right and there is no variation in requirement by age. A meta-study (an amalgamation of studies) concluded that “homeostatic mechanisms for calcium metabolism seem to be functional across a broad range of typical dietary calcium intakes to minimize calcium losses and accumulations.”
So, What Determines Strong Bones?
So, if dietary intake of calcium is not a major determinant of bone density what is? The answer seems to be exercise. Randomized controlled trials repeatedly demonstrate increases in bone density in both young and elderly. We also know that obese people tend to have stronger bones too. Several mechanisms seem to be involved and one is the mechanical effect of increased weight bearing on muscle that stimulates bone formation. But carrying that extra body fat increases our risk of all cause mortality so bulking ourselves up on calorie-dense food is not the recommended strategy here.
In 2020 a well-publicized study (using the 17 years old EPIC observational data) found the vegans had a 42% increase in chance of hip fracture even after adjusting for BMI. But no significant differences were observed in risks of wrist or ankle fracture. The number of vegans was very low, and the vegans were reporting ridiculously small amounts of dietary fibre - making the quality of their diets suspect. Nothing was known about the exercise regime of the subjects.
Protein consumption is understood to be a factor involved in bone density. That’s because protein places a complex role in transport mechanisms, enzymes and hormones associated with bone health. This doesn’t mean we have to obese about increase protein but simply include some main meals to ensure our RDA with higher levels for those of 65 years of age.
We can increase our calcium absorption with vitamin D. Vitamin D is vital for maintaining calcium homeostasis and bone remodelling. Vitamin D accomplishes this goal by enhancing the efficiency of the small intestine to absorb dietary calcium (and phosphorous). In the summer months we just need to get outdoors for a couple of hours a day. However, any combination of sunscreen usage, aging, and being resident in higher latitudes dramatically reduces synthesis of vitamin D3 in the skin. People of darker skin pigmentation are also at disadvantage in higher latitudes. So, at least in winter months, vitamin D should be supplemented for multiple benefits (including immunity). Vitamin D has additional roles in bone maintenance (discussed [below]).
Vitamin K is also of consideration. Aside from its established role in blood clotting, several studies indicate a critical function of vitamin K in improving bone health. However this research is not conclusive, but NHS website advises attention to vitamin K intake as a precaution. Vegans on a varied diet that includes green leafy vegetables should not be lacking in this fat-soluble vitamin.
Osteoporosis
Yet in the USA, osteoporosis and low bone mass are currently estimated to be a major public health risk for 53.6 million adults 50 years or older. The prevalence of osteoporosis increased with age, and differs by sex, race, and ethnicity. And the disease is progressive - the prevalence of osteoporosis was three times higher in men over age 80 years than in men aged 50 to 59 years.
In Europe Osteoporosis is high and on the rise. Across Europe there is a 22.8% of hip fracture for women aged 50 and over and a forecast increase of 23% between 2017 and 2030. This results in an estimated at 1,180,000 lost QALYs (Quality Adjusted Life Years) for the EU. As we shall see in chapter [x] on Dairy, this phenomenon is against a background of high dairy product consumption.
In a 2019 survey of 173 men and women aged between 25 and 50, more than 25% were found to have early signs of osteoporosis (a condition called osteopenia).
Exercise & Bone Health
Whilst some individuals might suffer from uncommon disease, surveys show at best only two thirds of the UK population exercise regularly and we tend to exercise less as we get older. This is unfortunate because exercise (both impact and weight bearing) increases bone density. Bone weight-bearing and resistance exercises are the best type for bone health. Mountain hiking, jogging, climbing stairs, playing tennis, and dancing are all useful. Resistance exercises (such as lifting weights and press-ups) can also strengthen bones.
Malcolm does some swimming and bicycling which is good for his muscles and his heart, but it doesn’t really hack it for bone health. Walking is helpful in limiting loss to bone strength but does not help reverse it. So, he’s recently decided to take up running – sadly this is not something his doctor proposed.
The NHS website stipulates a minimum of 2.5 hours of exercise week. A report by the British Heart Foundation found that UK 44% of UK adults never do any moderate physical activity at all. The chart here uses England as an illustration but note Wales, Scotland and Northern Ireland have even steeper declines with age.
As mentioned elsewhere is this book, there are dozens of proven reasons for taking regularly exercise and the rewards to both physical and mental health are substantial. Combining exercise with socializing can be a bonus.
Figure 1: Percent of England Population Undertaking Minimum Recommend Exercise
Exercise is valuable for bone heath at any age to slow the decline in bone density. In the modern developed economies, our lifestyles are incompatible with our physiology. This plays out not just for osteoporosis but also something called sarcopenia (muscle wastage) which can be observed for any age group. As the two conditions generally develop together this gave rise to a new clinical term ‘Osteosarcopenia’ for a growing health problem leading to the increased incidence of fragility fractures, greater morbidity, mortality and socioeconomic costs. Both conditions are addressed through exercise which is significant beneficial at any age in reversing the condition.
What About Caffeine?
Historically it was believed there are slight negative effects on calcium absorption from drinking too much coffee is not a concern given that it can have some positive benefits [discussed elsewhere]. More recent studies have concluded the long- term coffee consumption is associated with a lower risk of Osteoporosis.
The Myth of Dairy Products and Bone Health
Lanou et al conducted a review of studies published on the relationship between milk, dairy products, or calcium intake and bone mineralization. Of the 37 eligible studies 27 studies found no relationship between dairy (or dietary calcium intake) and bone health. In the remaining 9 reports, the effects on bone health are small and or confounded by vitamin D intake. In none of these clinical, longitudinal, retrospective, and cross-sectional studies was there clear evidence that increased consumption of dairy products resulted even a modestly consistent benefit for child or young adult bone health.
Which diet is best for bones?
A recent (2019) meta-analysis of 20 studies divided diets into three broad types "Healthy" "Milk/dairy," and "Meat/Western." The healthy including Mediterranean type diets comprising fruit, vegetables grains and beans but low dairy. There results showed a reduced risk of low bone density in the "Healthy" dietary groups, particularly for younger people. The "Meat/Western" pattern increased risk of low bone density, especially in older people. Surprising to some was the finding that the "Milk/dairy" dietary pattern resulted in the largest risk to bone density including across age/sex groups such as older women.
Note that there is evidence to demonstrate that milk and diary is not a superfood for bone health. A meta-study showed that in women (6 studies, 195,102 women, 3574 hip fractures), there was no overall association between milk intake and hip fracture risk. This make sense because we now know that calcium is almost all foods and the body’s calcium hemostasis mechanism.
Is dietary acid a cause of calcium loss?
Modern Western omnivores comprising animal products; salt and refined foods results in a diets of high acidity whilst diets of fruits and vegetable products are alkaline. The body has mechanisms to combat and prevent a state of metabolic acidosis. These include systems to neutralise the acidity including kidney excretion of acids using calcium stores. healthy humans, the normal range for blood pH is between 7.35 and 7.45.
It has been proposed that decades of acidic diet might contribute to the loss of bone mass, but evidence had been limited but supportive of the theory. And some high-quality trials showed no link.
Healthy Sources of Calcium
So how do we get an average of 741mg of calcium a day in our food from the health diet sources? Calcium is present in almost every plant and fruit. On a varied with plenty of fruit and vegetables you’d need to try very hard to not consume enough calcium.
Table 1: Example sources of Calcium
Food Calcium Mg
Spinach (one cup, cooked) 245
Chickpeas (one cup) 80
Chia Seeds (1 tbs) 42
Kale (1 cup, cooked) 177
Muesli (8 oz) 129
Apple (medium) 10
Onion (1 medium) 25
Orange (1 medium) 53
Grapes (1 cup) 15
Whole wheat Bread (1 slice) 71
Fig (medium) 18
Carrots (1 cup, cooked) 44
Potatoes (1 cup, boiled) 72
Peas 38
Beans (baked) 86
Broccoli (1 cup, cooked) 62
Blackberries (1 cup, raw) 41
Mushrooms (1 cup, cooked) 9
Almonds (10) 33
Tofu (1 cup) 106
Plums (6 medium) 24
Cabbage, Red (1 cup, raw) 40
So how can we NOT get enough calcium? It seems to be present in almost every fruit and vegetable?
Summary on Calcium
So, let’s summarize what we know about dietary calcium and bone health.
Osteoporosis is a common disease in Western society especially amongst the elderly and a serious concern for women.
Most Osteoporosis sufferers are not vegan - there is no association between osteoporosis and the vegan diet.
Dietary intake of calcium is adequate on a varied and balanced vegan diet. There is no advantage from including dairy products. The body regulates its calcium levels – except for supplemented calcium which causes that regulatory mechanism to fail. Supplemented calcium is associated with increased risks for heart attacks, strokes and kidney stones. Dairy product consumption is not required for bone health.
Consuming alcohol, smoking tobacco and lack of stress bearing exercise are three major contributory factors for declines in bone density, increased risk of bone fracture leading to ill-heath and death.
Vitamin D (sunshine or diet), dietary Protein and Vitamin K are helpful for calcium absorption and/or bone health. Vitamin D should be supplemented in winter months for those not living in equatorial regions.
Comments