High Dietary Acid Load Doubles Risk of Type II Diabetes in Lean Individuals! Causative or Corollary? Plus: Are Grains, not Meats the Main Offenders in the Modern Diet?

If you go for green, you are usually on the safe side of things... ah pHs ;-)
You will probably remember the association between higher acid levels (not even out of range), metabolic syndrome, lowered growth hormone release and a plethora of other ill-health effects I already hinted at in "How Could Bicarbonate Help You Lose Fat & Build Muscle" (read more). A new study from the Gustave Roussy Institute in France is now the first large scale study to provide relatively conclusive support for the hypothesis that there is a direct relationship between dietary acid load and the risk of cardiometabolic diseases and type II diabetes (Fagherazzi. 2013).

Credible evidence from large cohort

Fagherazzi et al. analyzed data from 66,486 women who were part of the E3N study (Etude Epidémiologique auprès des femmes de la Mutuelle Générale de l’Education Nationale), a French prospective cohort study of 98,995 female teachers, who were followed for incident diabetes over 14 years (the study started in 1999).
Latent Acidosis? Why do I care? As you can see in the image to the right, even latent acidosis can reduce thyroid hormone production, increase protein breakdown and inhibit mytochondrial function . The latter leads to increased ROS, lactate production & proton leak, while the former entails decreases in protein synthesis, IGF-1 & cardiac output. These changes have long thought to promote the development of the metabolic syndrome by increasing inflammation and reducing the basal metabolic rate (Berkemeyer. 2009).
During the 14-year follow-up period, a total of 1,372 cases of incident type 2 diabetes were validated. Fagherazzi et al.'s close analysis of the data revealed that there is a significant association between higher potential renal acid loads (PRALs) and the incidence of type 2 diabetes. Specifically, Fagharazzi et al. point out, ...
"[...] the highest PRAL quartile, reflecting a greater acid-forming potential, was associated with a significant increase in type 2 diabetes risk, compared with the first quartile (HR 1.56, 95% CI 1.29, 1.90)." (Fagherazzi. 2013)
A risk increase of 56%, alone, is a pretty impressive figure. What's even more impressive, though, is the fact that the association was significantly stronger among normal-weight women with a BMI <25 kg/m². For them the risk of developing type 2 diabetes almost doubles (+96%), when the dietary acid load is high. That's quite telling in view of the fact their baseline risk of developing T2D is low compared to those of the overweight study participants for whom the additional risk factor "dietary acid load" produced a significant (p = 0.03), but relatively low risk increase of only 28%.

The characteristics of the pro-diabetic diet

When we take a closer look at the actual data, there are dozens of statistically highly significant differences between the low and high pH quartiles (most of them with a p-value of p < 0.001). I initially tried to plot the differences, but that got way too chaotic, so I decided to make a list of items such as "higher energy intake (+15%)" indicating that the subjects with a high PRAL value (~the one's who were living on the more acidic side of the divide ;-) had a 15% higher energy intake than the subjects in the low PRAL quartile:
  • It may be coincidence, but in view of the anecdotal link between artificial sweeteners and heart-burn it's probably worth mentioning:  The most acidic study participants consumed 20% more artificially sweetened beverages (more about sweeteners)
    higher energy intake (+15%)
  • lower carbohydrate intake (-10%)
  • higher fat intake (+9%)
  • higher protein intake (+10%)
  • higher animal protein intake (+4%)*
  • lower fiber intake (-20%)
  • higher phosphorus intake (+16%)
  • lower potassium intake (-23%)
  • higher calcium intake (+10%)
  • lower magnesium intake (-22%)
  • higher sodium intake (+26%)
As a seasoned SuppVersity veteran, you will already have realized where this is heading: Higher energy intake, higher fat intake, hilariously low levels of potassium and magnesium, and salt intakes way beyond the 3g margin - all these are SAD (=standard American diet) hallmarks of the way the average Westerner (even in metropolitan France) eats. The 88% higher cheese intake, the 45% lower fruit + 25% lower veggie intake and 45% more of everyone's favorite "healthy" bread complete the picture that's emerging here: It's the Pizza Hut Diet ;-)

* The meat is not our only problem!

You will probably already have been wondering about the "*" and the fact that I highlighted higher animal protein intake (+4%)* in the previous list, right? Don't worry, I am not going to blame our problems on meat and suggest we all go vegan. The actual reason I highlighted the "bad" animal protein is a different one: the corresponding press release that came with the study (some of you may already have read it on Science Daily or other copy+paste 'science news portals'). It goes without saying that whoever wrote the short blurb used the study results for another sweeping blow at animal proteins by citing the following paragraph, and only but the following paragraph from the discussion of the results:
Suggested read: "Meat-Ology: The Link Between Red Meat, Cooking Techniques & Prostate Cancer" | more
"A diet rich in animal protein may favour net acid intake, while most fruits and vegetables form alkaline precursors that neutralise the acidity. Contrary to what is generally believed, most fruits such as peaches, apples, pears, bananas and even lemons and oranges actually reduce dietary acid load once the body has processed them. In our study, the fact that the association between both PRAL and NEAP scores and the risk of incident type 2 diabetes persisted after adjustment for dietary patterns, meat consumption and intake of fruit, vegetables, coffee and sweetened beverages suggests that dietary acids may play a specific role in promoting the development of type 2 diabetes, irrespective of the foods or drinks that provide the acidic or alkaline components."(Fagharazzi. 2013)
Obviously, it's going to be the first part of this paragraph, the one about the bad animal protein, that will get stuck in people's heads. The second part, the one that mentions rather casually that we are talking about total and not specific dietary acid loads, on the other hand, will go unnoticed. 

Figure 1: Food composition of paleo (top; estimation assumes a high meat intake) and modern US diet in % of total energy intake (Sebastian. 2013) - Don't forget: 1kg of lightly acidic foods are more acid forming than 100g of highly acidic foods!
Just as the fact that grains, which contribute an estimated 38% of the acid load yielded by the combined net acid-producing food groups in the contemporary diet (Sebastian. 2002), are just as, if not more problematic than the occasional steak of which the mainstream recommendations will tell you that you cannot have it more than once or twice a week, anyway.

'Paleo reasoning' to the rescue!?

In an effort to calculate the estimated net acid load of the 'ancestral', 'paleo' or 'whatever-you-want-to-call-it'-diet Sebastian et al. tested several scenarios, the worst of which a high protein, high fat version of the paleo diet (227g of protein, animal-fat content = 46%–63% of animal-food energy) still had a negative net endogenous acid production (NEAP = -7; Sebastian. 2013).

A low fat variety with a animal to plant food ratio of 35%:65% and an animal fat content of only 26% from animal-food energy and an even higher protein intake of 258g per day had a NEAP value of whopping -78. By "paleo standards" the average Westerner is thus consuming an extremely acidic diet, he is not genetically adapted to...  ;-)
Table 1: Acid-base value of common foods; positive values signify "acid forming", negative values "alkalizing" effects, the higher the figure the more pronounced the greater the impact of the given food is going to have (Cordain. 2012)
Paleo logic + scientific evidence = Win!  You all know that I don't buy the mainstream interpretation of the 'we are not adapted to...'-logic and the way it is employed by its followers in an almost religious way and against all scientific evidence.

What I do buy, however, are conclusions and recommendations that are based on both 'paleo logic' and scientific evidence - conclusions like the one Fagherazzi formulate in the last paragraph of their paper:
"[The] dietary acid load is directly associated with an increased risk of type 2 diabetes. From a public health perspective, dietary recommendations should not only incriminate specific food groups but also include recommendations on the overall quality of the diet, notably the need to maintain an adequate acid/base balance."
You want to know what foods Fagherazzi et al. may possibly be referring to? I already expected that. Just have a look at the table to the right, but don't forget: The study at hand does not prove causation. You could as well argue that it's the sum of dietary differences I listed as "characteristics of the pro-diabetic diet" which cause the diabetes. Anyways, the good news is: The solution, i.e. following a whole foods diet, is the same.

  • Berkemeyer S. Acid-base balance and weight gain: are there crucial links via protein and organic acids in understanding obesity? Med Hypotheses. 2009 Sep;73(3):347-56.
  • Cordain L . AARP The Paleo Diet Revised: Lose Weight and Get Healthy by Eating the Foods You Were Designed to Eat. John Wiley & Sons, Apr 23, 2012
  • Sebastian A, Frassetto LA, Sellmeyer DE, Merriam RL, Morris RC Jr. Estimation of the net acid load of the diet of ancestral preagricultural Homo sapiens and their hominid ancestors. Am J Clin Nutr. 2002 Dec;76(6):1308-16.
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