In July, a meta-analysis of the effect of calcium supplementation on heart attacks was published in the British Medical Journal (1). They found that people taking calcium supplements were more likely to have a heart attack. People have asked me if I think this means vegans should not supplement with calcium.

If you look at the study (the full paper is available for free at the link in the abstract below), they found that the increased risk of heart attack was limited to people who started out with a dietary calcium intake of 700 mg/day or more. Most vegans do not get that much calcium through foods. In most of the studies they examined, the level of calcium supplementation was substantially higher than 500 mg.

This study indicates that if you are an adult who gets 700 mg of calcium from your diet (including fortified foods), you probably shouldn’t take more than about a 300 mg supplement of calcium per day.

The DRI for calcium for ages 9 to 18 is 1,300 mg. This meta-analysis was conducted on older people trying to prevent osteoporosis and is probably not applicable for teenagers, whose bones are still building.

The DRI for calcium for people over 50 is 1,200. My recommendation for people in this age group who want to meet the DRI is to get at least 700 mg per day through foods and only supplement enough to make up the difference.

It’s worth noting that some observational studies of calcium intake (from foods, not supplements) have shown higher intakes to be protective against heart disease.

1. Bolland MJ, Avenell A, Baron JA, Grey A, MacLennan GS, Gamble GD, Reid IR.
Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis. BMJ. 2010 Jul 29;341:c3691.

Dear Jack,

I tried it and hardly any of my calcium tablet dissolved in that time. If this does matter can you recommend a vegan calcium supplement that will break down either tablet, powder or liquid?

Answer:

For some background, according to Advanced Nutrition & Human Metabolism (1999), the pH of the stomach is about 2.0. According to Krause’s Food, Nutrition, & Diet Therapy (2000), it ranges from 1 to 4. Vinegar tends to be about 2.0 to 3.0.

The New York State Department of Health has a web page Commonly Asked Questions About Calcium Supplements:

“Calcium must dissolve in your stomach before it can be absorbed in your intestines and then used by your body. A USP symbol on the label of a calcium supplement means that is it will dissolve in your stomach. If your supplement does not have a USP symbol, you can easily test it to find out if it will dissolve. Simply put the supplement into a glass of clear vinegar. This creates an acidic environment much like that of your stomach. Stir the solution occasionally. If the calcium supplement disintegrates within 30 minutes, it should dissolve in your stomach, too. If the supplement does not completely dissolve, choose an alternative calcium supplement.

“If you are taking acid blockers for indigestion, reflux or other gastrointestinal conditions, your body may use calcium citrate better than other calcium compounds. Acid blockers reduce the acid in your gastrointestinal tract that is usually required for calcium absorption. However, unlike other calcium compounds, calcium citrate does not require an acid environment for calcium absorption.”

I did a test with my Trader Joe’s Calcium Magnesium & Zinc supplement, which uses calcium carbonate – I broke one tablet in half and put it in 1/5 cup of apple cider vinegar. After 8 minutes it was completely dissolved.

The Office of Dietary Supplements at the National Institutes of Health has the following to say on their Dietary Supplement Fact Sheet: Calcium:

“The two main forms of calcium in supplements are carbonate and citrate. Calcium carbonate is more commonly available and is both inexpensive and convenient. Both the carbonate and citrate forms are similarly well absorbed, but individuals with reduced levels of stomach acid can absorb calcium citrate more easily. Other calcium forms in supplements or fortified foods include gluconate, lactate, and phosphate. Calcium citrate malate is a well-absorbed form of calcium found in some fortified juices [8]. The body absorbs calcium carbonate most efficiently when the supplement is consumed with food, whereas the body can absorb calcium citrate equally effectively when the supplement is taken with or without food [9].”

After the posts I made regarding the article, A Whole Diet Approach to Building Better Bones, in the Vegetarian Voice, two people contacted me to say that the World Health Organization recommends more than the 400 to 500 mg of calcium per day as stated in the article. According to Table 4.2 on p. 71 in their document, Vitamin and Mineral Requirements in Human Nutrition, Second Edition (2004), the WHO recommends:

1,300 mg for ages 10 to 18
1,000 mg for women 19 to menopause
1,300 mg for women past menopause
1,000 mg for men 19 to 65
1,300 mg for men ages 65+

And if you missed them, there have been many comments in response to these two posts (link, link).

Because the comments section to my post, Comments on Bone Health Article in the Vegetarian Voice, has gotten so long, I decided to create a new post that includes Dr. Amy Joy Lanou’s response and my follow-up.

From Dr. Lanou:

“I appreciate that you have taken the time to read our article and critique it. I fear, though, that you may have missed the main point. Our overall point is that the literature is pointing to the benefits to bone of a dietary pattern that high in fruits, vegetables and other plant-matter and low protein from animal sources along with adequate weight bearing physical activity to stimulate new bone cell formation. In our book (Building Bone Vitality) we highlight the importance of consuming the at least 17 other nutrients that are important to bone (including adequate, but not excessive protein and vitamin D among 15 others) as part of a healthy dietary pattern based on whole foods from plant sources.

“The single nutrient, calcium, or single food (cow’s milk) approach to osteoporosis prevention that we have grown up with and are still being sold is not working and may even be counterproductive. Vegan nutritionists arguing over whether the actual amount of recommended calcium should be 400 to 500 mg/day as the World Health Organization recommends for avoiding osteoporosis, >525mg a day as the Appleby and Key study would suggest, or the 700 or 800 mg/day that Jack Norris, RD recommends is part of the problem….not part of the solution. We are still focusing on that same single nutrient.

“I agree that the literature is not clear on what the exact optimum amount of calcium that an individual vegan may need is…in fact, the “right amount” quite likely has to do with the persons overall dietary pattern, activity level and other individual characteristics. It is, however, quite clear to me from a broad review of the literature that vegans, vegetarians, and omnivores alike are not getting a measurable benefit to hip fracture from pushing calcium intakes via dairy products and calcium supplements from 1000 to 1200 to 1500 to 2000 mg a day as some professionals recommend. I purposefully chose not to make a personal (albeit expert) recommendation for the level of calcium for vegans to consume but instead chose to go with the recommendation of an authoritative source (the WHO) as a useful starting point. I have no argument against a person targeting a calcium intake of 800 milligrams in a whole foods vegan diet (though I would be surprised if it did help prevent fractures more than targeting 500 mg/day calcium intake.) I would suggest, however, that people taking 1000 mg of supplemental or dairy calcium a day (or more) to prevent osteoporosis stop doing so and look instead at putting their efforts instead into moving to a dietary and lifestyle pattern that supports bone health.

“Please keep in mind that Building Bone Vitality and the article in question were both written to help vegetarians and omnivores alike to understand that milk drinking is not necessary for healthy bones and to urge people to move to a diet built from health-giving and bone-supporting foods the fruits, vegetables and other plant foods and away from a diet that is built from highly processed foods, meat and cheeses. I understand that our message may not be detailed or specific enough for some clinicians and long time vegans. (I appreciate that clinicians are working to make sense out of the research and make more specific recommendations than we have.) I hope your readers will forgive us for this lack of specificity if we manage to do some good with the message (for human health, for the animals, and for the environment) along the way.

“A couple other points of clarification:

“We do address the Appleby study in the book, but not in the article. Dr. McDougall has written about the Appleby study as well and he notes that none of the fractures experienced by the vegans in this study were fractures of the hip compared to 30 in the meat eaters, 9 in the fish eaters, and 14 in the vegetarians (dairy). Hip and spine fractures are arguably the most important end point for osteoporotic fracture. Dr. McDougall suggests and this is confirmed to some degree by correspondence with Dr. Key that the younger, thinner and more highly active vegans may have had more injuries due to vigorous physical activity.

“The meta-analysis of protein intake on bone health by Darling et al published in AJCN in 2009 fails to find either benefit or a lack of benefit of protein on bone. If one approaches this study from the perspective of trying to understand the relationship between dietary patterns and bone, this result is not surprising. Again these researchers are trying to understand relationship of the single nutrient (this time) protein, in the context of widely varying dietary patterns. It makes sense then that any effect of this single nutrient might be obscured in a meta-analysis since other potentially important dietary factors likely also varied widely (fruit and vegetable intake, potassium, vitamin D, sodium, etc.).”

Dr. Lanou,

Thank you for your response. I appreciate your goal of helping humans, animals, and the environment.
I have a few more comments below.

Jack

“Hip and spine fractures are arguably the most important end point for osteoporotic fracture. Dr. McDougall suggests and this is confirmed to some degree by correspondence with Dr. Key that the younger, thinner and more highly active vegans may have had more injuries due to vigorous physical activity.”

It is interesting that the vegans did not have any hip fractures. However, the study did adjust for physical activity and age, so those differences should not explain much of the results. And to my knowledge, there is no reason to think that the lifestyles of the vegans getting more than 525 mg of calcium were any less active than the vegans getting less than 525 mg, yet those getting more than 525 mg did not have a higher fracture rate.

The cross-sectional studies on vegans’ bone health have, for the most part, not shown them to have better bone health than omnivores. Those studies are cited here.

Thus, to date, there is very little evidence that a vegan diet helps prevent osteoporosis.

I have not seen a study, that tracked calcium intake over time, that showed people with intakes of 500 mg or less have less fractures than those with higher intakes.

I realize that Dr. Lanou’s point is that we need to take a holistic approach to bone health and not focus on one nutrient. But even holistic approaches only affect bone on a molecular level; if there isn’t enough calcium to maintain bones, it doesn’t matter if the approach is holistic or not.

Because of the harm it causes cows, I very much want to see an end to the dairy industry. But it could harm cows and humans just as much if, at the same time, we tell them that it is not important to concern themselves with calcium. In my opinion, the evidence doesn’t justify taking this risk.

The Fall 2009 issue of Vegetarian Voice magazine, the newsletter of the North American Vegetarian Society, has an article by Amy Joy Lanou and Michael Castleman, “A Whole Diet Approach to Building Better Bones.”

I will quote from the article to sum up their arguments:

“[W]e have known for at least 20 years that fracture rates are highest in areas where dairy and calcium consumption are also the highest.”

“Research shows that a low-acid diet, one that is high in fruits and vegetables and devoid of (or low in) animal protein (meats, poultry, fish, milk, eggs and cheese) helps keep calcium in bones.”

“[Osteoporosis is] actually a disease of calcium imbalance. Drinking milk and eating dairy foods provides calcium – but these foods are so high in protein that they draw more calcium out of bone then they replace.”

“We do need some calcium. The World Health Organization recommends 400 to 500 mg/day for people in countries at high risk of osteoporosis.”

“The best approach to osteoporosis prevention – the only one that makes scientific sense – is a diet very low in or devoid of animal foods and high in fruits and vegetables, combined with walking or equivalent exercise for 30 to 60 minutes a day, every day.”

If you have been following vegan nutrition advocacy for the past two decades, nothing above should be new to you. And here are the major problems I have with it:

1. Most non-vegans in Western countries get around 800 to 1200 mg of calcium per day. At this level of intake, I agree that there is little evidence that to prevent osteoporosis one needs even more calcium. However, Lanou and Castleman imply that all you need is a vegan diet containing 400 – 500 mg of calcium per day and walking for 30 to 60 minutes for strong bones. And they leave out the most important study published to date on bone health and vegans, a 2007 report from the EPIC-Oxford study which showed that vegans had a 30% higher rate of bone fractures than did meat-eaters and lacto-ovo vegetarians!

In that study, the vegans who got more than 525 mg of calcium had the same rate of bone fractures as the meat-eaters and lacto-ovo vegetarians, showing that vegans need more than 525 mg of calcium. (In the study, 32% of vegans had calcium intakes between 525 and 699 mg per day, and 24% had greater than 699 mg per day.)

This is the only study looking at the bone fracture rates of vegans.

2. Lanou and Castleman base most of their argument on the idea that animal protein leeches calcium from the bones. As I posted a few weeks ago, a meta-analysis looking at bone health and fractures found that “Overall, the weight of the evidence shows that the effect of dietary protein [including animal protein] on the skeleton appears to be favorable to a small extent or, at least, is not detrimental.”

In my opinion, the argument that a primary cause of osteoporosis is animal protein has always been on shaky ground.

3. Lanou and Castleman leave vitamin D out of their final recommendations (they briefly mention you can get it from the sun earlier in the article). Vitamin D can be a significant problem for many vegans and needs to be addressed in discussions of bone health.

4. I do not see why it is necessary to make an argument that people only need 400 to 500 mg of calcium per day, when the evidence is so lacking (and actually points in the other direction). What harm could come from encouraging vegans to get at least the low end of what is a normal amount of calcium (like 700 to 800 mg/day) in Western countries? None. But what harm could come from vegans not getting that much? Only osteoporosis!

In summary, there is no direct evidence that a vegan diet with only 400 to 500 mg of calcium per day prevents osteoporosis. The direct evidence is just the opposite.

More info on vegan diets and bone health.

A meta-analysis looking at protein intake and bone health was published this month in the American Journal of Clinical Nutrition (1).

In terms of bone mineral density (BMD), the authors reported:

“Overall, there was very little evidence of a deleterious influence of protein intake on BMD, with most cross-sectional surveys and cohort studies reporting either no influence or a positive influence. Thus, 15 cross-sectional surveys found a statistically significant positive relation between protein intake and at least one BMD site. However, 18 studies found no significant correlation between protein intake and at least one BMD site.

“The cohort studies also identified little evidence of any deleterious influence of protein intake on bone. … [N]o studies showed a significant increase in BMD loss with increased protein intake, and only one study showed a significant decrease in BMD loss with increased animal and total protein intakes.”

In terms of bone fracture rates, the authors reported:

“Overall, the [seven] cohort studies indicated either a benefit or no effect of protein intake on hip fracture relative risk, with only one study reporting a significant increase in risk with increasing animal protein intake and increasing animal to vegetable protein ratio. Three studies found a decreased relative risk of hip fracture with increasing animal, total, and vegetable protein intakes. Two studies found no significant association of animal protein with fracture risk, whereas 2 studies found no association of total protein with fracture risk. Last, 2 studies found no relation between fracture risk and vegetable protein.”

In summary:

“Overall, the weight of the evidence shows that the effect of dietary protein on the skeleton appears to be favorable to a small extent or, at least, is not detrimental. However, the long-term clinical importance of the effect is unclear, and a reduction in fracture risk was not seen. More research is required to resolve the protein debate. In the meantime the protein intakes and balance of different protein sources as indicated in the current healthy eating guidelines represent appropriate dietary advice.”

Reference

1. Darling AL, Millward DJ, Torgerson DJ, Hewitt CE, Lanham-New SA. Dietary protein and bone health: a systematic review and meta-analysis. Am J Clin Nutr. 2009 Dec;90(6):1674-92. Epub 2009 Nov 4.