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:

• Our Calcium page
• Our FAQ Should we be concerned about salt?

Resources

• Preventing and Treating Osteoporosis (Webinar Recording) – (1hr 48 min video) Michael Greger, MD, January 2024. This is an excellent summary of the research into osteoporosis.
• Osteoporosis – The Diet and Lifestyle Connection – Dustin Rudolph, Pharmacist
• Diet and Osteoporosis and the Broken Bone Business – (45 min. video) John McDougall, MD, Presented at an Advanced Study Weekend.
• McDougall’s Moments: Osteoporosis – (3 min. video) John McDougall, MD
• Phytates for the Prevention of Osteoporosis – (4 min. video) Dr Michael Greger presents the research into phytates and osteoporosis and includes sources used.
• Healthy Bones – Preventing and Reversing Osteoporosis – Dr Michael Klaper (video, US$20 digital download)
• How A Bone Disease Grew To Fit The Prescription – Alix Spiegel
• What is osteopenia, and what should be done about it? – Nelson B. Watts, MD
• Bone & Muscle Strengthening Workout – Exercise Tips That Help Prevent Osteoporosis – Switch4Good

Peer reviewed articles:

• Bischoff-Ferrari, H. A., Dawson-Hughes, B., Baron, J. A., Burckhardt, P., Li, R., Spiegelman, D., . . . Willett, W. C. (2007). Calcium intake and hip fracture risk in men and women: a meta-analysis of prospective cohort studies and randomized controlled trials. American Journal of Clinical Nutrition, 86(6), 1780-1790.
• Bischoff-Ferrari, H. A., Dawson-Hughes, B., Baron, J. A., Kanis, J. A., Orav, E. J., Staehelin, H. B., . . . Willett, W. C. (2011). Milk intake and risk of hip fracture in men and women: a meta-analysis of prospective cohort studies. Journal of Bone and Mineral Research, 26(4), 833-839.
• Bolland, M. J., Leung, W., Tai, V., Bastin, S., Gamble, G. D., Grey, A., & Reid, I. R. (2015). Calcium intake and risk of fracture: Systematic review. BMJ, 351, h4580.
• Chiodini, I., & Bolland, M. J. (2018). Calcium supplementation in osteoporosis: useful or harmful? European Journal of Endocrinology, 178(4), D13-D25.
• Evans, C. E., Chughtai, A. Y., Blumsohn, A., Giles, M., & Eastell, R. (1997). The effect of dietary sodium on calcium metabolism in premenopausal and postmenopausal women. European Journal of Clinical Nutrition, 51(6), 394-399.
• Michaelsson, K., Wolk, A., Langenskiold, S., Basu, S., Warensjo Lemming, E., Melhus, H., & Byberg, L. (2014). Milk intake and risk of mortality and fractures in women and men: Cohort studies. BMJ, 349, g6015.
• Slawta, J. N., & Ross, R. (2004). Exercise for osteoporosis prevention. Health & Fitness Journal, 8(6), 12-19.
• Sotos-Prieto, M., Rodriguez-Artalejo, F., Fung, T. T., Meyer, H. E., Hu, F. B., Willett, W. C., & Bhupathiraju, S. N. (2024). Plant-Based Diets and Risk of Hip Fracture in Postmenopausal Women. JAMA Network Open, 7(2), e241107. *NEW*
• Tai, V., Leung, W., Grey, A., Reid, I. R., & Bolland, M. J. (2015). Calcium intake and bone mineral density: systematic review and meta-analysis. BMJ, 351, h4183.
• Wallace, T. C., Jun, S., Zou, P., McCabe, G. P., Craig, B. A., Cauley, J. A., . . . Bailey, R. L. (2020). Dairy intake is not associated with improvements in bone mineral density or risk of fractures across the menopause transition: data from the Study of Women’s Health Across the Nation. Menopause, 27(8), 879-886.

 

Page created 16 November 2020
Page last updated 16 January 2021

By Dr Malcolm Mackay

Sodium requirements, actual intake vs recommended intake

Sodium is an essential nutrient, but the requirements are relatively low. We evolved in an environment of sodium scarcity and our bodies are exceptionally good at conserving sodium and can adapt to low intakes by minimizing sodium loss in sweat and urine. The absolute minimum requirement is only about 115mg per day but to allow for environmental and individual variation, the recommended safe minimum intake is 500mg per day. The Australian Nutrient Reference Values lists adequate intake as 460-920mg per day.

The average Australian intake is about 3600mg per day. This is far too high. The World Health Organization recommends a maximum intake of 2000mg sodium per day. The Nutrient Reference Values previously set the suggested target at 1600mg but revised this to 2000mg in 2017, claiming the new “suggested dietary target of 2000mg/day is more realistic as it represents a total diet that meets all nutritional requirements, given the current food supply.” It seems that they surrendered to a food industry that continues to add too much salt to our basic food staples. The Nutrient Reference Values review of the research reported that increased sodium intake was associated with increased blood pressure throughout the range of intakes from 1200mg and 3300mg per day – there was no point in this range at which there was not a relationship between sodium intake and blood pressure. This suggests to us that the daily sodium intake target for optimal health is no more than 1200mg per day.

 

Regular salt is a crystalline substance made up of sodium ions and chloride ions. These ions go their own way when dissolved in water. The sodium is the part that interests us because it has the greatest effect on our health. Other sodium ‘salts’ include sodium bicarbonate (rising agent) and monosodium glutamine (MSG, a ‘flavour enhancer’).

 

Salt and sodium numbers:
* 1000mg of salt contains approximately 400mg (390mg actually) of sodium
* Conversely multiply sodium by 2.5 to convert back to grams of salt
* One teaspoon of salt is about 5g of which 2g (2000mg) is sodium

Adverse effects of salt

The body controls how much fluid it has in the blood and tissues by carefully regulating sodium excretion through the kidneys. We then pee out any excess water to keep the saltiness of the blood constant. Those of us with a low salt intake notice that a single salty evening meal dries up the pee stream until the next day, then we experience an increased fluid output – most Australians top up the excess sodium at every meal and therefore always carry excess fluid. The extra fluid in the body raises blood pressure – a leading risk factor for strokes and heart disease. Excess sodium also impairs endothelial function and increases cardiovascular risk independent of blood pressure. The high potassium content of a plant-based diet partially offsets the effects of sodium on blood pressure.

Salt and the gut
A high salt diet, the amount in the usual Australian diet, has adverse effects on the gut. Gastric cancer is strongly associated with salt intake (Umesawa et al. 2016). Salt is a preservative and has antimicrobial effects on our gut microbiome, reducing the production of beneficial short chain fatty acids by good microbes. Salt increases symptoms of bloating – one study found that adding the usual amount of salt back to a low salt diet increased symptoms as much as adding extra fibre (Peng 2019).

Salt and autoimmune and inflammatory conditions
Salt has been implicated in arthritis, autoimmune disease, and inflammatory bowel disease (Sigaux et al 2018). Cell studies and mouse studies have shown us how salt can upregulate inflammation and autoimmune disease while human studies, although limited, have found an association with salt intake and worse disease outcomes. A high salt internal environment transforms T helper cells into more inflammatory th17 immune cells and suppresses regulatory T cells – thus increasing autoimmune disease severity and inflammation. The evidence is incomplete but the treatment, a low salt diet, has only good side effects.

Salt and calcium excretion
Increased sodium intake increases urinary excretion of calcium. This can result in calcium being removed from bone to maintain blood levels. This study found that the effect was worse in post-menopausal women and may contribute to osteoporosis in the long term (see Evans et al 1997). See also our page on Osteoporosis

Mental health
High salt diets may not be good for mental health. Fluid retention, impaired blood supply, inflammation and reduced gut microbiome health may adversely affect brain health and mood. Some people report agitation and insomnia with both salt and MSG. Studies in mice suggest that high salt diets may play a role in cognitive impairment and dementia (Faraco et al 2019).

Our taste for salt

Humans have a natural taste for salt – perhaps its related to the environment of salt scarcity that we evolved in, or a method of detecting which plants are rich in minerals. A little bit of salt may taste good, but with continued use our taste buds become dulled and, like a drug, we need more and more to get the desired effect. With our senses dulled, natural foods taste bland without the addition of salt and we are trapped.

Salt can act as an appetite enhancer. We tend to eat more of something when its salty (Bolhuis et al. 2016). Adding a small amount of salt at the table can make whole plant foods more palatable during transition. Conversely, keeping it SOS-free (sugar, oil, salt) can assist with weight loss. Salt may be part of the reason why some people overeat bread.

The food industry know that salt is a flavour and appetite enhancer – it’s a cheap way to make their products taste better and to sell more product to their salt habituated customers. Industry targets for salt reduction are weak and long term. The approach seems to be to reduce salt at the top end of the added salt range while keeping everything else moderately salty. The target for bread, for example, is 400mg per 100g which is still far too high. Our health authorities and legislators have failed to adequately protect the Australian people from the health consequences of excess salt. The US salt industry seems to have taken the tobacco industry approach of creating controversy and doubt over the adverse effects of current salt intake: see Don’t Be Confused by Big Salt

Sources of sodium

People are often unaware of how much salt they eat because most of it is added before the food gets to the table. Bread and cereals are big contributors. A single slice of wholemeal bread contains about 200mg. Soups and crackers are often high in salt. Many sauces and flavourings, including some spice powder mixes are high in salt. Meals eaten in cafes and restaurants are almost always high in salt. We often see recipes with multiple sodium sources such as tamari, curry paste plus vegetable stock or miso.

It is a common misconception that miso does not count towards salt intake. Miso paste contains 200-400mg per 10g (1 tbsp miso can weigh 20g) and a good quality miso soup sachet, 671mg. There is research showing miso does not raise blood pressure but this is observational data and the authors note that miso may have been a marker of a more traditional Japanese diet (Kanda et al 1999). The soybean component may offset some of the effects of the high sodium content – but why not just eat the soy bean without the salt. Research on miso and cancer reported that the risk of gastric cancer in subjects who consumed 3 and ≥4 bowls/day of miso soup was approximately 60% higher than in those who consumed less miso soup (Umesawa et al 2016) – which is consistent with other research on sodium intake and gastric cancer. So, we recommend caution consuming miso – use in very small amounts.

Sodium content of foods

Food	Serving size	Sodium per serve	Sodium per 100 g /ml
Bread, Irrewarra Wholegrain	1 slice, 70 g	267 mg	382 mg
Miso (various)	15 g	350-700 mg	2335-4670 mg
Soy sauce, ‘less salt’	15 ml	571 mg	3808 mg
Soy sauce, regular	15 ml	1025 mg	6833 mg
Tamari, salt reduced	10 ml	415 mg	4150 mg
Bragg all purpose seasoning (aminos)	5 ml 20 ml (tabsp)	320 mg 1040 mg	6400 mg
Massel, Chicken stock powder, salt reduced	1 heaped teasp	700 mg	*Not relevant
Massel, Vegetable stock powder	1 heaped teasp	1032 mg	*Not relevant
Massel, Chicken stock cubes, Salt reduced	1 cube	1416 mg	*Not relevant
Massel, Vegetable stock cubes	1 cube	1808 mg	*Not relevant

*Note that commercial vegetable stocks are very high in sodium. The nutrition label makes it difficult to determine how much sodium you are actually adding to your cooking, unless you make it up as suggested and use it in a very dilute form.

When it comes to the type of salt used, it does not make much difference to the sodium content. Gourmet salts – Himalayan, Celtic, sea salt – contain nearly as much sodium as ordinary salt. Adding these to your food is no healthier than just adding ordinary table salt. The amount of other minerals they contain is small and one would need to eat a toxic amount of salt for these to contribute significantly to daily mineral intake. If you are going to use any salt it may as well be iodised salt given that Australian soils are known to be low in iodine.

Managing your salt intake

There are some strategies we use to manage our salt intake. Check food labels for sodium content and consider how many serves you are likely to eat in one day. A good rule of thumb for foods that contribute significantly to your daily intake is a sodium target of less than 1mg of sodium per calorie (4.2 kilojoules). The 1mg/calorie rule does not apply to items to sauces, spices and flavouring agents that are used in small quantities – dietitian Jeff Novick suggests condiments could have a sodium to calorie ratio of 4:1. However, some products – soy sauce, tamari, Bragg’s aminos – are extremely high in sodium, and it does not take much to push up your daily sodium intake. Assume that meals eaten out are high in sodium. If a dish tastes unnaturally delicious, it may be because it is high in sodium or MSG.

There is little doubt that consuming salt at anywhere near the current Australian intake is injurious to health. The question remaining is whether a low salt diet (eg. 1200mg sodium) will support our health as well as a no added salt diet (eg. 500mg). We don’t have the answer as the research has not been done. For most whole food, plant-based people the challenge will be just keeping their sodium intake in the low range, given the number of food products that have added salt.

We recommend a safe upper limit of daily sodium intake of 1200 mg (3 g salt).

How low in salt you need to be will depend on your health status, health goals and genetics (as some individuals are more salt sensitive than others). If you suffer from hypertension, heart disease, fluid retention, PMS, arthritis, autoimmune disease, inflammatory bowel disease, osteoporosis, IBS or bloating, then you may need a very low sodium intake for best results.

See also:

• Hypertension
• Calcium
• Gut Health
• Osteoporosis
• Other FAQs

Resources

• Nutrient reference values for Australia and New Zealand: Sodium – National Health and Medical Research Council. (2006, 2017 revision).
• Salt, Sugar, and Fat – T Colin Campbell (July 2020).
• Five Important Facts About Sodium/Salt Intake – Jeff Novick, RD
• Confused on use of Sea Salt – Jeff Novick, RD answering a question in the McDougall Forum
• Sodium Levels – Use of Salt – Jeff Novick, RD in the McDougall Forum
• Finding & Removing the Hidden Salt – Jeff Novick, RD
• Are you as-salting your immune system? – Robyn Chuter
• Hypertension: Salt Still Matters – by Carra Richling for Ornish Lifestyle Medicine
• Sodium & Autoimmune Disease: Rubbing Salt in the Wound? (5 min video) – Michael Greger M.D., 2017 ·
• Hughes, S. (2023). Low-Salt Diet Cut BP by 6 mm Hg in 1 Week: CARDIA-SSBP. Retrieved from https://www.medscape.com/viewarticle/998495

Peer-reviewed articles

• Bolhuis, D. P., Costanzo, A., Newman, L. P., & Keast, R. S. (2016). Salt Promotes Passive Overconsumption of Dietary Fat in Humans. Journal of Nutrition, 146(4), 838-845.
• Dickinson, K. M., Keogh, J. B., & Clifton, P. M. (2009). Effects of a low-salt diet on flow-mediated dilatation in humans. American Journal of Clinical Nutrition, 89(2), 485-490.
• Faraco, G., Hochrainer, K., Segarra, S. G., Schaeffer, S., Santisteban, M. M., Menon, A., . . . Iadecola, C. (2019). Dietary salt promotes cognitive impairment through tau phosphorylation. Nature, 574(7780), 686-690.
• Jung, S. M., Kim, Y., Kim, J., Jung, H., Yi, H., Rim, Y. A., . . . Ju, J. H. (2019). Sodium Chloride Aggravates Arthritis via Th17 Polarization. Yonsei Medical Journal, 60(1), 88-97.
• Kanda, A., Hoshiyama, Y., & Kawaguchi, T. (1999). Association of lifestyle parameters with the prevention of hypertension in elderly Japanese men and women: A four-year follow-up of normotensive subjects. Asia Pacific Journal of Public Health, 11(2), 77-81.
• Ma, H., Xue, Q., Wang, X., Li, X., Franco, O. H., Li, Y., . . . Qi, L. (2022). Adding salt to foods and hazard of premature mortality. European Heart Journal, 43(30), 2878-2888.
• Peng, A. W., Juraschek, S. P., Appel, L. J., Miller, E. R., 3rd, & Mueller, N. T. (2019). Effects of the DASH Diet and Sodium Intake on Bloating: Results From the DASH-Sodium Trial. American Journal of Gastroenterology, 114(7), 1109-1115.
• Sigaux, J., Semerano, L., Favre, G., Bessis, N., & Boissier, M. C. (2018). Salt, inflammatory joint disease, and autoimmunity. Joint, Bone, Spine: Revue du Rhumatisme, 85(4), 411-416.
• Toussirot, E., Bereau, M., Vauchy, C., & Saas, P. (2018). Could sodium chloride be an environmental trigger for immune-mediated diseases? An overview of the experimental and clinical evidence. Frontiers in Physiology, 9, 440.
• Umesawa, M., Iso, H., Fujino, Y., Kikuchi, S., Tamakoshi, A., & Group, J. S. (2016). Salty Food Preference and Intake and Risk of Gastric Cancer: The JACC Study. Journal of Epidemiology, 26(2), 92-97.

Page created 8 October 2020
Last updated 11 February 2023 (resources section)