Drinking soda and osteoporosis - all the acid!

EvgeniZyntx

TL;DR - Don't worry about the random cola, get your overall nutrition in.

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I'll post the studies mentioned at the bottom.

There exists study evidence(1) that in the general popluation, it terms of epidimiology, drinking soda is associated with osteoporosis. Of note in that study are a couple of things - total phosphorous wasn't particularly higher and the increase in lower bone mineral density (BMD) was seen with Cola consumption but not other soft drinks.

A reasonable conclusion from the looking at the study that is most cited for "soda is responsible of bone loss" is that it ISN'T soda but something related to Cola drinking. Possibly caffeine? Possibly phosphoric acid which is present in Cola but a lot less in other sodas.

A PRIOR study (2) looked into this and highlighted that phosphoric acid, citric acid had no role in calcium excretion. However, drinking caffeinated drinks was already known to cause an increase in the amount of calcium excreted in urine and also known to be a passing effect; the body reduces significantly the amount of calcium excreted at other times of the day to make up for this loss. It's a buffering process.

The authors of study (2) also posit that the actual reason for the lower BMD is due to displaced milk consumption; the logic goes like this: If one is drinking mostly soda, one isn't drinking milk.

It's interesting to read the discussion of study (1).

In the present study, there was no significant difference in milk consumption by level of cola intake. However, total calcium intake was lower in the women with the highest cola intakes, and this may contribute to their low BMD. In addition, fruit juice intake was lower in high compared with low cola consumers. We previously showed that BMD was associated with fruit and vegetable intake and the apparent effects of cola consumption may be related to poor dietary quality. However, adjustment for fruit juice intake (or for total fruit and vegetable intake) did not significantly change the results.

(my bold)

So yes, drinking one thing for another might be the reason.

The caffeine content of cola may contribute to lower BMD, and results were consistently stronger for intake of caffeinated cola than for intake of decaffeinated cola. Adjustment for caffeine intake from other sources did attenuate, but did not eliminate, the association between decaffeinated cola and loss of BMD. The remaining significance of decaffeinated cola may be due to yet unexplained actions of phosphoric acid. Although adjustment for the overall daily calcium-to-phosphorus intake ratio did not significantly attenuate results, it is less clear how regular use of a beverage containing a dose of phosphoric acid, with no calcium and no other basic forming or neutralizing components, may affect BMD over a long-term exposure. In addition to calciuric effects of high phosphorus and low calcium combinations, phosphoric acid present in the gut may form a complex with dietary calcium to block its absorption. It is possible that this may reduce the calciuric effect but still have a negative effect on bone by reducing total calcium availability. However, the observed associations may also be due to incomplete control of confounding. More research on the potential mechanisms by which phosphoric acid may affect bone is needed.

(My bold)

Might be related to some unknown mechanism or could be something the authors are overlooking.

And it only affects women, or at least:

It is interesting that our findings of an association between cola intake and BMD in women but not men are consistent with several studies that found associations for girls but not boys (4-6). It is not clear why females would be more sensitive to the effects of cola than are males.

Btw, it seems that people that drink soda are less likely to eat their vegetables and fruit. (Displaced nutrition is a thing.) And that the correlation to bone density might just be related to overall nutritio (3).

In conclusion, a study correlates cola drinking with lower BDM (and possibly osteoporosis) but it's unclear why, other research doesn't clarify that it's related to phosphoric acid (feel free to find something that does, I'd be interested).

Finally, does an acidic diet really have an effect on bone density? The short answer is NOT LIKELY. A more recent study looking at the causal relationship between diet acidity and BMD in 55 studies and ran an analysis, see study (4).
Their conclusion is clear: A causal association between dietary acid load and osteoporotic bone disease is not supported by evidence and there is no evidence that an alkaline diet is protective of bone health.

For good bone health, eat your veggies, have that dairy and get some sun. Don't worry about the random cola.

(1)

Am J Clin Nutr. 2006 Oct;84(4):936-42.
Colas, but not other carbonated beverages, are associated with low bone mineral density in older women: The Framingham Osteoporosis Study.
Tucker KL1, Morita K, Qiao N, Hannan MT, Cupples LA, Kiel DP.
Author information 1Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111, USA. katherine.tucker@tufts.edu
Abstract
BACKGROUND: Soft drink consumption may have adverse effects on bone mineral density (BMD), but studies have shown mixed results. In addition to displacing healthier beverages, colas contain caffeine and phosphoric acid (H3PO4), which may adversely affect bone.

OBJECTIVE: We hypothesized that consumption of cola is associated with lower BMD.

DESIGN: BMD was measured at the spine and 3 hip sites in 1413 women and 1125 men in the Framingham Osteoporosis Study by using dual-energy X-ray absorptiometry. Dietary intake was assessed by food-frequency questionnaire. We regressed each BMD measure on the frequency of soft drink consumption for men and women after adjustment for body mass index, height, age, energy intake, physical activity score, smoking, alcohol use, total calcium intake, total vitamin D intake, caffeine from noncola sources, season of measurement, and, for women, menopausal status and estrogen use.

RESULTS: Cola intake was associated with significantly lower (P < 0.001-0.05) BMD at each hip site, but not the spine, in women but not in men. The mean BMD of those with daily cola intake was 3.7% lower at the femoral neck and 5.4% lower at Ward's area than of those who consumed <1 serving cola/mo. Similar results were seen for diet cola and, although weaker, for decaffeinated cola. No significant relations between noncola carbonated beverage consumption and BMD were observed. Total phosphorus intake was not significantly higher in daily cola consumers than in nonconsumers; however, the calcium-to-phosphorus ratios were lower.

CONCLUSIONS: Intake of cola, but not of other carbonated soft drinks, is associated with low BMD in women. Additional research is needed to confirm these findings.

(2)

Am J Clin Nutr. 2001 Sep;74(3):343-7.
Carbonated beverages and urinary calcium excretion.
Heaney RP1, Rafferty K.
Author information 1Creighton University Osteoporosis Research Center, Omaha, NE 68131, USA. rheaney@creighton.edu
Abstract
BACKGROUND: Intake of carbonated beverages has been associated with increased fracture risk in observational studies. The usual explanation given is that one or more of the beverage constituents increase urinary calcium.

OBJECTIVE: We assessed the short-term effects on urinary calcium excretion of carbonated beverages of various compositions.

DESIGN: An incomplete random block design was used to study 20-40-y-old women who customarily consumed > or =680 mL carbonated beverages daily. Four carbonated beverages were tested: 2 with caffeine and 2 without. Two contained phosphoric acid as the acidulant and 2 contained citric acid. The study included one neutral control (water) and one positive control (skim or chocolate milk). Serving size was 567 mL for the carbonated beverages and water and 340 mL for the milks. Beverages were consumed with a light breakfast after an overnight fast; no other foods were ingested until urine collection was complete. pH, titratable and total acidity, sodium, creatinine, and calcium were measured in 2-h (morning) fasting and 5-h postbeverage urine specimens.

RESULTS: Relative to water, urinary calcium rose significantly only with the milks and the 2 caffeine-containing beverages. The excess calciuria was approximately 0.25 mmol, about the same as previously reported for caffeine alone. Phosphoric acid without caffeine produced no excess calciuria; nor did it augment the calciuria of caffeine.

CONCLUSIONS: The excess calciuria associated with consumption of carbonated beverages is confined to caffeinated beverages. Acidulant type has no acute effect. Because the caffeine effect is known to be compensated for by reduced calciuria later in the day, we conclude that the net effect of carbonated beverage constituents on calcium economy is negligible. The skeletal effects of carbonated beverage consumption are likely due primarily to milk displacement.

(3)

http://www.ncbi.nlm.nih.gov/pubmed/21772969
J Osteoporos. 2011;2011:102686. doi: 10.4061/2011/102686. Epub 2011 Jul 2.
The oslo health study: a dietary index estimating frequent intake of soft drinks and rare intake of fruit and vegetables is negatively associated with bone mineral density.
Høstmark AT1, Søgaard AJ, Alvær K, Meyer HE.

(4)

Nutr J. 2011 Apr 30;10:41. doi: 10.1186/1475-2891-10-41.
Causal assessment of dietary acid load and bone disease: a systematic review & meta-analysis applying Hill's epidemiologic criteria for causality.
Fenton TR1, Tough SC, Lyon AW, Eliasziw M, Hanley DA.
Author information 1Department of Community Health Sciences, University of Calgary, Calgary, AB, Canada. tanisfenton@shaw.ca
Abstract
BACKGROUND: Modern diets have been suggested to increase systemic acid load and net acid excretion. In response, alkaline diets and products are marketed to avoid or counteract this acid, help the body regulate its pH to prevent and cure disease. The objective of this systematic review was to evaluate causal relationships between dietary acid load and osteoporosis using Hill's criteria.

METHODS: Systematic review and meta-analysis. We systematically searched published literature for randomized intervention trials, prospective cohort studies, and meta-analyses of the acid-ash or acid-base diet hypothesis with bone-related outcomes, in which the diet acid load was altered, or an alkaline diet or alkaline salts were provided, to healthy human adults. Cellular mechanism studies were also systematically examined.

RESULTS: Fifty-five of 238 studies met the inclusion criteria: 22 randomized interventions, 2 meta-analyses, and 11 prospective observational studies of bone health outcomes including: urine calcium excretion, calcium balance or retention, changes of bone mineral density, or fractures, among healthy adults in which acid and/or alkaline intakes were manipulated or observed through foods or supplements; and 19 in vitro cell studies which examined the hypothesized mechanism. Urine calcium excretion rates were consistent with osteoporosis development; however calcium balance studies did not demonstrate loss of whole body calcium with higher net acid excretion. Several weaknesses regarding the acid-ash hypothesis were uncovered: No intervention studies provided direct evidence of osteoporosis progression (fragility fractures, or bone strength as measured using biopsy). The supporting prospective cohort studies were not controlled regarding important osteoporosis risk factors including: weight loss during follow-up, family history of osteoporosis, baseline bone mineral density, and estrogen status. No study revealed a biologic mechanism functioning at physiological pH. Finally, randomized studies did not provide evidence for an adverse role of phosphate, milk, and grain foods in osteoporosis.

CONCLUSIONS: A causal association between dietary acid load and osteoporotic bone disease is not supported by evidence and there is no evidence that an alkaline diet is protective of bone health.

Edit: closing the underline.

MyChocolateDiet

IDK. I find that my husband's cola consumption is coinciding with him having more bone density. ;-)

neanderthin

Epidemiology, the weapon of mass confusion. pH balance is tightly controlled within the body, but who knows........too many variables....vit D for example.

EvgeniZyntx

Epidemiology, the weapon of mass confusion. pH balance is tightly controlled within the body, but who knows........too many variables....vit D for example.

Yep.

Vit D intake was controlled but, for example, level of activity was not. LBM was not. Are women that drink a lot of cola less likely to have other exercise/health habits that affect mineral bone density? yepyepyep. Since cola is so demonized, if you worry about exercise, as a group, you might just reduce cola consumption....

MyChocolateDiet

I am as against restriction of the taking of the D as I am against restriction of the taking of the cola.

neandermagnon

Epidemiology, the weapon of mass confusion. pH balance is tightly controlled within the body, but who knows........too many variables....vit D for example.

Yep.

Vit D intake was controlled but, for example, level of activity was not. LBM was not. Are women that drink a lot of cola less likely to have other exercise/health habits that affect mineral bone density? yepyepyep. Since cola is so demonized, if you worry about exercise, as a group, you might just reduce cola consumption....

To fail to account for physical activity is a major oversight IMO.... seeing as weight bearing exercise is a major factor in increasing bone mineral density.....

Tuala42

Thank you for sharing!

snowflake954

bump

Galatea_Stone

I am as against restriction of the taking of the D as I am against restriction of the taking of the cola.

I'm not getting enough D.

TL; DR, but does this mean if I drink cola, I'll get more D?