There’s a general view out there, I think, that vegetarian and vegan diets are, on balance, healthier than those that include flesh foods including meat. I personally don’t agree with this view. My beliefs on this are partly based on the evidence that non-vegetarians don’t appear to have their lives curtailed by their consumption of flesh foods [1]. Also, there is at least some evidence that vegetarian and vegan diets can come up short on certain nutrients such as iron and vitamin B12.
Because vegans do not eat dairy products, there can be a tendency for their diet to be relatively low in calcium. I think the role of calcium and dairy products in bone health has been somewhat overstated, but I was nonetheless interested to read about a study published last year which assessed bone fracture risk in non-vegetarians, vegetarians and vegans [2]. The study followed a total of more than 35,000 individuals aged 20-89 for a period of just over 5 years.
The researchers discovered that meat-eaters, fish-eaters and vegetarians had very similar risk of fracture. However, compared to them, risk of fracture in vegans was 30 per cent greater.
The obvious potential reason for this is the generally lower calcium content of the vegan diet. So the authors of the study went on to factor this into the equation. And when they did, they discovered that if a vegan diet contains at least 500 mg (525 mg to be precise) of calcium each day, then there was no increased fracture risk.
Now this sort of ‘epidemiological’ study cannot prove that low calcium intake caused the enhanced fracture risk, but the results sure are consistent with this finding.
So, it seems like a generally good idea for vegans who want to optimise their bone health to make sure they have a decent calcium intake. Good vegans sources of calcium include sesame seeds (including tahini), nuts (especially almonds), and beans.
References:
1. Key TJ, et al. Mortality in British vegetarians review and preliminary results from EPIC-Oxford. Am J Clin Nutr 2003;78(suppl):533S-8S
2. Appleby P, et al. Comparative fracture risk in vegetarians and nonvegetarians in EPIC-Oxford. Eur J Clin Nutr, 2007;61(12):1400-6.
Vegans may need to ensure adequate dietary intake of vitamin D too (also important for bone health), discounting those who get adequate amounts from sun-exposure.
I have my concerns about vitamin A and some minerals as well. Plants don’t contain true vitamin A (retinol), they contain beta-carotene, a substance which is converted to vitamin A at only 1/6 (or even less) efficiency. The conversion of carotene to vitamin A also requires fat in the diet, a makronutrient which many plant foods are low in. Vegan/vegetarian diets are also notoriously low in saturated fat, which is important for the absorbtion of important minerals [1-4].Sure, it’s easy to ensure adequate amounts of vitamin A even on a vegan diet but not everyone is a nutrition expert. Vitamin A deficiency is a common problem in many countries so i think it’s a fair argument.
On top of that, the very staples in vegan diets such as grain are high in antinutrients such as phytic acid which can reduce the absorption of important minerals drastically. For example, the absorption of Zinc from grains is relatively low [5]. That may explain why zinc deficiency is common in third-world countries where grain consumtion is high…
An article [6] on the subject of micronutrients and bone health cites…
” In animal studies, Mg deficiency causes decreased bone strength and volume, poor bone development, and dysfunctions in bone formation and resorption. Zinc is the fourth mineral known to have a primary role in bone formation. Because zinc is used to metabolize protein, it is necessary for the creation of the collagen that forms a framework for mineralization. Zinc deficiency has been linked to osteoporosis.”
“Four vitamins are known to take part in bone formation: vitamins D, K, C, and A.”
Vegans can be at risk for deficiency in all those minerals, and all vitamins too except maybe K and C.
Greetings from Sweden,
Andreas
1. Mahoney AW, et al. Effects of level and source of dietary fat on the bioavailability of iron from turkey meat for the anemic rat. Journal of Nutrition, 1980: 110 (8): 1703-1708.
2. Johnson PE, et al. The effects of stearic acid and beef tallow on iron utilization by the rat. Proc Soc Exp Biol Med, 1992; 200 (4): 480-486.
3. Koo SI, Ramlet JS. Effect of dietary linoleic acid on the tissue levels of zinc and copper, and serum high-density lipoprotein cholesterol. Atherosclerosis, 1984; 50 (2): 123-132.
4. Van Dokkum W, et al. Effect of variations in fat and linoleic acid intake on the calcium, magnesium and iron balance of young men. Ann Nutr Metab, 1983; 27 (5): 361-369.
5. Sandstrom B, Almgren A, Kivisto B, Cederblad A: Zinc absorption in humans from meals based
on rye, barley, oatmeal, triticale and whole wheat. J Nutr 1987;117:1898—1902.
6. Nutrition & bone health
Townsend Letter for Doctors and Patients, April, 2005 by Jule Klotter
http://findarticles.com/p/articles/mi_m0ISW/is_261/ai_n13471774
I feel duty-bound to advise everyone out there that dairy products do not contribute to bone health. Why? Because they are highly acidic and alter the ph balance of the blood in favour of acidity, causing calcium (that is alkaline) to be leeched from the skeleton to neutralise the acidity. Cheese is one of the foods contributing to the osteoporosis epidemic. Read Dr Marilyn Glenville’s book on the subject. Furthermore, dairy foods are high in phosphates that prevent the uptake of calcium.
I have eaten a lot of cheese in my lifetime, until now, having found out I have thinning of the bones.
All of my life I h
To Miss Sylvia Wainhouse – sorry but your “milk is acidic” claim is just wrong.
Your body contains a stomach full of concentrated acid that is used to break food down into its constituent parts. The acidity or alkalinity of any food taken in is overpowered by the acidity of the stomache. (pH 1-2).
Comparing milk (pH 6.7) and water (pH 7.0) shows that any effect on the overall acidity would be similar to drinking a glass of water, and would in fact reduce and dilute to overall acidity.
Curretl, there are more than 75 diagnosis for thinning bones from Anorexia to Wilsons disease. Milk is not amongst them
As for your claim that Marilyn Glenville’s book told you this. I suggest you “re-read” it. Her book is about natural alternatives to HRT where she recommends soya products, with their high contents of phyto (plant)-oestrogens as a means of reducing menopausal symptoms. Nothing against milk, nothing to do with acidity.
So if your bones are thinning, don’t blame the cheese…
To David (somewhat belatedly)
Your comment seems to put the emphasis on milk and then you make the remark at the end “So if your bones are thinning, don’t blame the cheese…” Firstly, I am not ‘blaming’ cheese, but it clearly was a contributing factor and did nothing to prevent it.
Regarding Dr Marilyn Glenville’s book, I was not referring to, nor did I mention ‘Natural Alternatives to HRT’, so to suggest I “reread it” is arrogance on your part. The actual book title just escapes me at the moment but it is regarding the real cause and cure of osteoporosis and has ‘osteoporosis’ in the title. It was launched a number of years ago, prior to her book ‘Osteoporosis, the Silent Epidemic’.
I appreciate you pointing out that the pH of milk is 6.7 but when you consider that it is mostly added to tea, coffee and cereals such as porridge, all of which are highly acidic, you can see how this affects the pH balance of the body overall in favour of acidity, thereby necessitating that calcium (alkaline) be leeched from the skeleton to correct the imbalance. Does this not then lead to thinning of the bones or ultimately to osteoporosis? I rest my case.