Are the recommended doses of vitamins sufficient for tall Australian women?

By Candice Prosser

Candice is a journalist and member of the

Tall Australian Women Facebook group, you might remember her 2024 National News report.

Those blessed with height can become somewhat accustomed to getting noticed. So it's quite the irony that we can feel so unseen in many insidious ways.

My most recent experience of this was when I started taking vitamin supplements (including calcium and vitamin D) to help improve my bone density.

Naturally, I began familiarising myself with the recommended daily intakes (RDIs) of all the bone-boosting vitamins.

It soon occurred to me that I'm nowhere near the average-sized female that these recommendations might be most suited to.

Is the intake of vitamins we're advised to ingest enough for our tall bodies?

In my attempt to get some concrete answers I reached out to many organisations, including the National Health and Medical Research Council (NHMRC).

Most helpfully, the NHMRC was able to confirm that the Nutrient Reference Values, on which the recommendations for nutritional intake are based, used an average height for adult women of 164cm.

I stand at 183cm tall. I am clearly going to have significantly more bone mass than the average female. Same goes for the amount of blood in my body, and so forth.

Therefore, it stands to reason that the recommended dosage of daily vitamins for me needs to be upscaled too. Right?!

Put simply, if the RDIs are based on an average sized female, how can they be adequate for us tall folk?

A valid question, but one I would discover does not have a straightforward answer.

So begins my quest to solve this conundrum.

I felt this needed further research and clarification, not just for me, but for all my fellow tall comrades.

Unfortunately, finding a clear answer has felt a bit like drawing blood out of a stone.

I began by asking a medical specialist (endocrinologist) I went to see regarding my bone health. My question left him rather stumped.

He considered what I'd said for a long moment and agreed that it made sense that I may need a bit more calcium than others, due to my long bones.

BUT (how did we know there was a "but" coming?), as there are no medical guidelines about it, he couldn't help me.

Long sigh.

I made inquiries with an organisation called Healthy Bones Australia (HBA) that exists to create awareness and advocacy for better bone health, and to help prevent osteoporosis.

Getting an answer from them has taken months.

One example of many conversations I've had with Healthy Bones Australia.

Here's what they eventually told me:

"In an individual person, assessment of calcium adequacy can be determined by paired serum and 24 hour urinary samples."

There are no "specific indicators" for tall people who "may or may not have higher bone mass".

"What we call adequate intakes (and in the case of vitamin D, adequate sun exposure) are very much approximations, since there is considerable biological variation and other additional factors that affect how much calcium and vitamin D people need.

"Being tall is one very small factor in comparison to others that we know about."

HBA also told me that many adults don't get enough calcium from their diet, and don't get enough vitamin D from safe sun exposure.

"So bottom line, it is likely that tall people, like many other people, are not getting lots of calcium and vitamin D, so they should maybe try to get a bit more (preferably from diet and judicious sun exposure)."

I also reached out to the Therapeutic Goods Administration (TGA), the federal body that's responsible for regulating all vitamins and minerals in Australia to ensure they meet "standards for safety, quality, and efficacy".

In a statement, a TGA spokesperson told me that while the TGA does not provide specific recommendations on nutrient intake, it will consider the RDIs for nutrients when assessing medicines.

"The current public health guidelines do not provide adjustment of vitamin or calcium doses based on height or bone mass," the TGA told me.

"Individuals with specific health concerns or unique physiological needs are advised to consult a healthcare professional for personalised advice."

So who makes these recommendations? And how?

The RDIs for nutrients are published in the Nutrient Reference Values for Australia and New Zealand Including Recommended Dietary Intakes, established by the NHMRC.

When I started exploring that document, I noted the good old disclaimer at the start. It states that the document is a general guide.

It goes on to say that "the recommendations are for healthy people and may not meet the specific nutritional requirements of all individuals."

My research tells me that the recommendations are generally based on age, sex and life stage (e.g., pregnancy, lactation), rather than height or bone mass.

A colourful concoction of daily vitamins that currently inhabits my pill organiser.

I asked the NHMRC to clarify whether height or bone mass is ever a factor that's considered for the RDIs it sets.

A spokesperson for the NHMRC told me that "measured body weight and heights" taken from national surveys are "considered when setting reference bodyweights for various age/sex groups."

That's where that 164cm average height statistic comes in, which is actually based on data from nearly a decade ago. (In case you're curious, the average height for adult men from the same survey in 2006 was 178cm)

The spokesperson also echoed what the TGA told me, that the guidelines are not adjusted according to height or bone mass.

TGA: "These recommendations are for the majority (97-98 per cent) of the healthy population and may not meet the specific nutritional requirements of all individuals."

So it's a calculation that works for most. But what about the statistical outliers? The long-legged lasses amongst us who don't fit the "standard"?

When I did ask my GP, and then my specialist about this, they really couldn't give me a clear answer. They had nothing to reference.

If none of the healthcare professionals we are encouraged to consult "for personalised advice" are being provided with any evidence-based guidelines about this, where does that leave us?

So, again, I went straight to the body that sets those guidelines (the NHMRC) and asked them: "Are the RDIs sufficient for women over six feet tall?"

I'm told we're "unlikely" to be deficient if we follow the RDIs.

In response to this question, the NHMRC informed me that the RDIs both "meet" and "exceed" the "known nutritional needs of practically all healthy people".

While they're based on "group needs", they're apparently quite generous when they set these intake guidelines.

"RDIs exceed the actual nutrient requirements of practically all healthy people."

So, if they're somewhat overestimating these intakes, that could potentially be helpful for those of us who may, theoretically, require it. Yes?

An extract from the Nutrient Reference Values for Australia and New Zealand

"They have generous factors to adjust for differences in how nutrients are absorbed and metabolised," the NHMRC said.

In other words, that means it is "unlikely that individual women will be deficient at the level of the RDI."

Good to know. And that is the most concrete reassurance I've been able to find.

Can a nutritionist help?

Maybe. I approached an experienced nutritionist who also happens to be a member of the tall tribe.

Holistic nutritionist Pascalle Nelemans said while tall individuals are likely to need more energy, and therefore vitamins, it is dependent on a few more factors than just our height.

That's because the Basal Metabolic Rate (BMR) is influenced by many factors (yes, including body size).

As the Cleveland Clinic website spells out: "The more body tissue and cells you have, the more energy your body requires to maintain them."

"In my eyes, this translates that tall people might need more energy than short people," Ms Nelemans told me.

"However, this depends further on the shape of their body i.e. are they slim or do they carry more fat?

"I think it is important for everybody to get adequate vitamins and minerals to support our bodies, and I usually do investigative work for each individual by taking a thorough case/health history."

And does she believe that the RDIs are adequate for those over six feet tall?

Well, that depends.

"I find this question a little hard to answer; I usually approach this question by looking at each individual person, how their health is and what their blood work shows."

We need more calcium as we age (thanks menopause).

It's worth noting that the RDI of calcium increases from 1,000 mg per day to 1,300 mg per day once we get past a certain age (50 for women and 70 for men).

It's a difference of 300 mg, which equates to 30 per cent more calcium for older Australians and post-menopausal women.

That's the maximum recommended dose for the most at-risk age group.

The Healthy Bones Australia website states that "excessive calcium intake is not recommended". But makes no mention of what "excessive intake" means.

I asked Healthy Bones Australia to clarify, and they told me that it would be "difficult to get too much calcium from food", but warns that "taking more than one or at most two calcium supplements a day (they are usually 600mg) is not a good idea" and taking supplements should be done under medical guidance.

"If tall people try hard get the recommended amounts of calcium and vitamin D, as outlined on HBA website, they’ll be fine."

And in case you were wondering, Vitamin D is not considered a nutrient in the usual sense, since it is supplied mainly by sunlight on the skin (rather than from food intake).

Therefore, there are seasonal variations in vitamin D levels in Australia, and it very much depends on your exposure to sunlight.

Calcium supplements like these should be taken under medical guidance

Conclusions of my research deep dive:

• The recommendations for nutritional intakes are based on an average height for adult women of 164cm.

• The current public health guidelines do not provide adjustment of vitamin doses based on height or bone mass.

  
  

• The recommendations are for the majority (97-98 per cent) of the healthy population and "may not meet the specific nutritional requirements of all individuals".

  
  

• RDIs are "generous" and "exceed" the actual nutrient requirements of "practically all healthy people". So, the experts say it is "unlikely that individual women will be deficient at the level of the RDI."

  
  

• Many people do not get enough calcium from their diet, and may need to take supplements (under medical guidance).

  
  

• Individual medical advice is recommended for those who are concerned about their vitamin intake.

  
  

My closing thoughts ...

Sadly, it has taken numerous inquiries and many dead ends to get the information I've been seeking.

I'm an experienced journalist and I don't give up that easily. But what about the rest of us who deserve guidelines and advice that are adequately suited to our tall bodies?

I got the distinct impression that most of the organisations and experts I reached out to had never been asked this question before.

And while many found it to be an interesting request, they had very little, if no reference points to answer it.

And, as a result, we don't have clear answers tailored to our height - other than the reassurance that we're "unlikely" to be deficient if we follow the RDIs.

I quite enjoyed this mission. However, I really feel that it shouldn't require this level of effort to get clear information that's relevant to us.

Perhaps, if nothing else, my queries to the experts may have helped shine a light on an area of the population they so often overlook.

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