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  • Writer's pictureDr Meredith Wall

What did you eat today?

So, here's my day on a plate:

Do you think you did better, or worse?

The analysis above compares my intake with the Australian/New Zealand recommended daily intakes (RDI) for a women, aged 31-50 (

I'm always quite surprised by how bad my diet apparently is. Here's what I ate today:

  • A bowl of granola with full fat Greek yogurt, a peach and some cherries

  • Some Vita-weat cracked pepper crackers with cheddar cheese and two dill pickles

  • A big bowl of Moroccan tagine with sweet potato, carrots and lentils, and quinoa

  • Three cups of green tea, and a lot of mineral water

This isn't actually my breakfast. It was similar though, just not quite as nice.

Admittedly, it's not my best day, but it's certainly not my worst!

So what's good and what's not-so-good?

First of all, the analysis shows that I ate approximately 1154.3 kcal in total, with 14% of calories from protein, 32.1% of calories from fat, and 53.9% of calories from carbohydrate.

You can see I'm not meeting my protein requirement, however I'm not really concerned about that, because most days I eat quite a lot more protein than this.

Calcium is a problem, because it's consistently low, probably due to my tendency not drink coffee. Even on the good days, when I have cereal with milk and a hot chocolate at work, calcium is still only 50-70% of the RDI. 1000mg of calcium per day is actually quite a lot! So why is the RDI so high? And should I be taking a daily calcium supplement?

Picture of dairy foods
Dairy products are rich in calcium, but so are some leafy greens (for example, kale, broccoli rabe, or Chinese greens), canned fish containing bones (for example, sardines or salmon), and many fortified foods like tofu, orange juice or various nut milks.

Interestingly, not everyone agrees with an RDI of 1000 mg of calcium. For example, Dr. Walter Willett, chair of the Department of Nutrition at Harvard T.H. Chan School of Public Health, believes that the World Health Organization recommendation of 500 mg/day is more likely to be appropriate, or perhaps the United Kingdom's RDI of 700 mg/day.

Willett points out that there are established risks to trying to meet a relatively high RDI by taking a calcium supplement. For example, taking calcium supplements has been associated with an increased risk of kidney stones. Furthermore, an analysis of 15 randomized controlled trials by Bolland et al. (2010) linked calcium supplementation with an increased risk of myocardial infarction. Some researchers have speculated that calcium supplements may contribute to heart disease by increasing blood levels of calcium, which can cause arteries to stiffen and blood pressure to rise.

In 2013, Bolland et al. published a follow-up paper, in which they state:

"At the population level, any effects of calcium supplements on fracture risk are outweighed by the increased cardiovascular risk. Likewise, at an individual level, the increased cardiovascular risk will generally outweigh any benefits on fracture prevention. Therefore, the widespread use of calcium supplements to improve bone health should be abandoned."

They conclude that: "current evidence suggests that dietary calcium intake does not require close scrutiny for the majority of people".

This is intriguing, given that several years ago, in my efforts to more faithfully adhere to the Australian/NZ RDI for calcium, I purchased a combined calcium/vitamin D supplement, which I neglected to take (perhaps fortunately) because of the unpleasantly large tablet size. However, many people around the world may be taking calcium supplements that potentially cause more harm than good.

No longer recommended for the general population.

In this context, Vitamin D is also worth touching on, as you can see that it's also woefully deficient in the analysis above. But wait, I hear you say, it will be fine, because vitamin D is made in the skin through exposure to ultraviolet radiation in sunlight. However, the amount produced varies widely from person to person. Additionally, if you follow the advice to reduce your risk of skin cancer by keeping covered and wearing sunscreen (very necessary in NZ and Australia), you're also cutting your vitamin D production.

Dr. Willett therefore recommends going lower on calcium and higher on vitamin D than the guidelines suggest—500 to 700 mg a day of calcium and 800 to 1,000 IU of vitamin D. He points out that this should allow you to get the calcium you need from food items alone, but you might need a vitamin D supplement (800-1000 IU per capsule).

But ... is this recommendation without controversy? Of course not!

In 2016, Manson et al. published a noteworthy paper in the New England Journal of Medicine titled “Vitamin D Deficiency: Is There Really a Pandemic?” The long and short of it is that the authors believe that we are over-screening for vitamin D deficiency, and unnecessarily treating individuals who are perfectly fine. They suggest a more appropriate cutoff for vitamin D deficiency would be 12.5 nanograms of 25-hydroxy-vitamin D per millilitre of blood, rather than the previously recommended 20 ng/mL, or even the 40-60 ng/mL recommended by the Endocrine Society in 2011.

The controversy is ongoing, however most can agree on the recommendation to screen individuals at a higher risk of deficiency, such as perimenopausal women, or people diagnosed with osteopenia, and that vitamin D supplementation is warranted in women at midlife with levels less than 20 ng/mL.

Anyway, I think this is a good example that demonstrates how much we still have to learn about nutrient RDIs for people, let alone for dogs and cats. The more I learn about nutrition, the more I'm reminded of Socrates famous statement: ""I neither know, nor think that I know".

Read the full 2013 paper by Boland et al. here:

Read the full 2016 paper by Manson et al. here:

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