Osteoporosis

By Dr Malcolm Mackay

Not calcium deficiency

Osteoporosis is not caused by calcium deficiency. There is more osteoporosis in countries where dairy foods are consumed, and calcium intakes are high. Whether the calcium comes from supplements, dairy foods or other sources, a high calcium intake does not protect individuals against osteoporosis (Bischoff-Ferrari et al 2007; Bolland et al 2015; Tai et al 2015).

Dairy

The bulk of research does not support the marketing claim that dairy foods are protective against osteoporosis. This was reconfirmed by the SWAN study (Wallace et al. 2020) which found that the amount of dairy foods consumed had no effect on perimenopausal bone loss or fracture rates. A large prospective Swedish study (Michaelsson et al. 2014) found that liquid milk (but not cheese or yoghurt) was associated with an increased fracture rate which the authors attributed to the inflammatory effects of galactose (a component of milk sugar).

Disuse atropy clasts and blasts

Osteoporosis is a disuse atrophy of the bones made worse by the dietary factors. Bones are continuously being broke down and rebuilt to match the loads that are placed on them. Osteoclasts (cells in bone) break down bone that is damaged or superfluous to needs and osteoblasts (cells in bone) lay down new bone in proportion to how much stress is placed on each section of bone. The system provide just the right amount of bone strength to match the amount of weight the bone must carry and the strength of the muscles pulling on the bone. Weight bearing and strong muscles are a prerequisite for strong bones.

What is osteoporosis?

Osteoporosis is defined in terms of bone density relative to young adults in a reference population (of Caucasian ethnicity). If your bone density is more than 2.5 standard deviations below the mean (<2.5) then you have osteoporosis. This is your t score. Your z score is your bone density ranking for your age group. Fractures due to minimal trauma might also be considered part of the definition. A t score of -1.5 to -2.5 is often referred to as osteopenia – this is not osteoporosis.

Drug treatment

The pharmaceutical industry educates doctors on the treatment of osteoporosis and supports campaigns to detect osteoporosis. Osteoporosis drugs have side effects and are only moderately effective. The most commonly used drugs work by inhibiting bone breakdown rather than supporting the formation of new healthy bone.

Some other medications have an adverse effect on bone density. PPIs, a class of drugs widely used to suppress stomach acid, reduce calcium absorption. Corticosteroids and excess thyroid hormone increase bone loss.

One way street?

The traditional view of bone density and aging is that after reaching ‘peak bone mass’ in early adulthood there is an inexorable age-related decline in bone density – a one-way street down which we can only change our speed of decline. However, bone is always remodelling, and research has shown that strengthening the muscles of a limb can also increase the bone strength of that limb. Bone density is a more like a two-way street with a steep gradient where gaining bone takes a lot more effort than losing bone.

Calcium, Vitamin D and other nutrients

Calcium is a major component of bone, but you cannot force your bones to grow stronger by eating more calcium. Your body will only absorb as much calcium as it can utilise. Calcium supplements may increase the risk of heart attacks and should be taken in low doses or not at all.

Vitamin D is required for calcium absorption and bone maintenance and is more likely to be in short supply than calcium. Supplements can prevent vitamin D deficiency when sun exposure is inadequate due to low UV levels in winter and indoor living.

Many of the other vitamins, minerals, and protein that we get from whole plant foods are important for bone formation. Phytonutrients such as the phytates in whole grains also support bone health.

Protein, salt and bone loss

Protein from animal sources imposes an acid load on the body due to relatively high levels of sulfur containing amino acids. The body neutralises the acid by releasing calcium from the bone and then excreting the acid and calcium through the urine. The higher the animal protein intake, the more difficult it becomes to absorb enough calcium to offset the urinary loss. Animal protein and sedentary lifestyles may account for much of the osteoporosis in affluent nations.

Sodium and calcium excretion by the kidneys are intertwined and an increased salt intake causes increased calcium loss (Evans et al 1997).

Inflammation and bone toxins

At a recent conference presentation on joint health the orthopaedic surgeon displayed photographs of living bone that had been transected in preparation for joint replacement surgery. Areas of inflamed diseased bone were visibly apparent in many of the images. There are multiple mechanisms by which bone becomes this damaged. ‘Artery disease anywhere is artery disease everywhere’ and bone is no exception, being a highly vascular organ and therefore susceptible to diseased arteries and sludgy blood. The typical Australian diet has many toxic components which can cause tissue damage and inflammation throughout the body – AGEs, endotoxins, TMAO and cooked meat carcinogens to name a few. The inflammatory effect of these substances compounds the chronic inflammation that stems from obesity and poor metabolic health to suppress the formation of healthy new bone. In contrast, whole plant foods provide an array of phytonutrients that dampen down inflammation and oxidative stress to provide an optimal environment for the maintenance of healthy bone.

Bone adapts to load

Bone in a healthy person or animal will adapt to the loads under which it is placed. – Dr. Julius Wolff (1836-1902) anatomist and surgeon.

Exercise is a prerequisite for strong bones. Any activity that compresses or flexes a bone repeated over a period of time will cause the bone to become stronger. Even if a drug could do this, it could not construct bone along the appropriate lines of stress.

What sort of activity?

Weight bearing activities such as walking are recommended but are only part of the solution.

Bone strength is proportional to muscle strength. Sarcopenia (muscle wasting due inactivity or malnutrition) will be accompanied by osteoporosis regardless of weight bearing. Weight bearing through the legs will not protect you from vertebral crush fractures or fractures of the wrist and shoulder. Prevention and reversal of osteoporosis requires activities that increase muscle strength.

Strength training

In premodern society everyday life involved bending, squatting, lifting, carrying loads, walking many kilometres per day and much less sitting time. If this is not how you live, then you may need to actively work to incorporate strength building activities into your daily life in addition to your daily step count. A range of strength exercises may include partial squats, calf raises, sit ups and upper limb pushing, pulling and lifting. You may need assistance from a personal trainer, physiotherapist or exercise physiologist depending on your baseline state of health and fitness. Strength building activities are not limited to gym work – group exercise sessions, dancing and even some types of yoga can build strength and bone.

What about the spine?

The type of bone in vertebrae is different to the bone of hips and wrists and the bone density t score for the spine is often much lower than the hip. Building strong hip bones just requires enough squatting and weight bearing but building vertebral bone strength is enigmatic. Strengthening the muscles that support the trunk could be a good start but weight bearing through the upper body may be necessary to build strong vertebrae. One way to do this is to wear a weight vest for several hours per week.

Balance

Instability heightens the risks of fragility by increasing falls. Regular balance exercises markedly reduce fracture risk in elderly subjects. Agility and balance may be as important as bone strength in preventing fractures.

Conclusion

Osteoporosis is caused by a combination of inactivity and a typical Western diet, rich in animal protein and processed foods. Dairy foods and calcium supplements are not effective for preventing or reversing osteoporosis. A whole foods, plant-based diet provides all the nutrients and phytonutrients required for healthy strong bones. Physical activity is critical to maintaining a healthy skeleton.

See also:

Resources

Peer reviewed articles:

 

Page created 16 November 2020
Page last updated 16 January 2021

Calcium

You do not need to drink milk to get enough calcium. You will not make your bones stronger by drinking milk.

If you don’t believe these statements, don’t worry, you are not alone. Seventy years of marketing has convinced most health professionals that dairy foods, or a high-calcium substitute, are essential for human health. This is a rather narrow nutritional view when one considers that cow’s milk is only consumed by a minority of the world’s population, and for a relatively short period of human history. Most of the world’s population, including the majority of those of Asian or African descent, are lactose intolerant and suffer abdominal pain and diarrhoea if they drink milk.

While it is true that dairy foods are rich in calcium and that calcium is an essential nutrient for bone health, increased dairy consumption is not associated with stronger bones. In fact, a large Swedish study (Michaelsson et al 2014) found that higher milk consumption was associated with a higher rate of hip fractures (as well as a higher mortality rate). The higher prevalence of osteoporosis in countries that consume more dairy foods suggests that dairy products are not an effective preventative strategy.

You don’t need to reach for calcium fortified foods to get enough calcium on a whole foods plant-based diet

Like other minerals, calcium comes from the ground. Plants absorb it and animals in turn eat plants. Cows get their calcium from the grass. We can obtain all our calcium needs from whole plant foods, many of which have moderately high calcium levels. Some vegetables have a higher “nutrient density” for calcium than dairy foods (see Nutrient Density page). Interestingly, calcium is better absorbed from vegetables than milk, over 50% vs 32%. Many whole plant foods are rich in calcium – a cup of chopped kale, for example, provides as much absorbable calcium as a cup of milk.

Calcium content of food

Dairy (and ‘dairy alternatives’) has its own food group in the Australian Dietary Guidelines but this is no longer the case for the Canadian dietary guidelines. A liberal interpretation of ‘dairy alternatives’ might include beans, greens and other high calcium whole plant foods. A plant-based ‘milk’ with a similar calcium content to cow’s milk is not necessary. Indeed, it has been argued that a more appropriate comparator for plant ‘milks’ is human breast milk which has only a third of the calcium content of cow’s milk.

The recommended daily intake for calcium in Australia is extraordinarily high, up to 1300mg per day, a level which few people reach. It remains to be seen whether this will be revised in future guidelines given the evidence that high dietary calcium intakes are not protective against osteoporosis (Bolland et al 2015). The World Health Organization (2004) notes that calcium needs are increased by high intakes of animal protein and sodium. Dietary animal protein increases urinary loss of calcium and at very high protein intakes it can be difficult to absorb enough calcium to offset losses. WHO suggests a lower calcium requirement where animal protein intake is lower, and if sodium intakes were also lower as in developing countries then the calcium requirement would be even lower, e.g. 450mg (WHO 2004, p. 82).

A study of older Chinese men and women on a “plant-based diet” in the Journal of Bone and Mineral Research (Fang et al. 2016) suggested there was an optimal range for calcium intake, and that both very low and very high intakes were associated with higher fracture rates. It may surprise you to learn that this range of optimal intakes was 250-650mg/day for women and 275-780mg/day for men. In the discussion the authors suggest that policy makers rethink the dietary reference intakes for calcium and the policy of milk promotion in developing countries. These results provide evidence that older Chinese men and women eating a plant-based diet may require half as much calcium than their Western counterparts for fracture prevention – approximately 400mg per day. A typical whole foods plant based diet provides at least 500mg of calcium per day and more often 700-800g without having to reach for calcium fortified foods.

Calcium supplements are not effective in preventing osteoporosis and clinical trials have observed an increase in kidney stones and cardiovascular events. Australian doctors are now being urged to consider the risks and benefits before recommending calcium tablets. Osteoporosis is not caused by calcium deficiency and it is not prevented by calcium supplements. See Osteoporosis page. Getting enough calcium on a dairy-free diet of whole plant foods is a non-issue and there is no need to consume plant ‘milks’ for calcium.

See also:

Resources

Peer-reviewed articles:

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Page substantially revised 9 December 2019
Page last updated 30 December 2019