For today’s edition of Dear Mark, we’ve got a question about dietary acid load and type 2 diabetes. A new study’s just come out suggesting that the acid load of the diet does indeed have a significantly negative impact on our health and may actually cause type 2 diabetes. The reader is understandably worried, so I dig into the research and try to see what’s going on. Then, for Dear Carrie, my lovely wife answers a reader’s question about the safety of homemade baby food.
I was under the impression that this was rubbished a long time ago provided you ate plenty vegetables? Unfortunately I can’t get hold of the full “The Times” article without subscribing but it was in the UK print edition. I thought you would be able to work your magic with journals to uncover what is really at work here.
Hey Euan, thanks for bringing this to my attention. I was able to find the full text of the study (PDF). It’s called “Dietary acid load and risk of type 2 diabetes: the E3N-EPIC cohort study” and tracks the type 2 diabetes incidence across 14 years among 66,000 French women.
So yeah, you could look at the results and claim that a high dietary acid load is associated with type 2 diabetes. That would be true. There is an association. The data is clear. But let’s look a little closer and see if there’s another way to consider the issue.
If you scroll on down to Table 1 in the study text, you’ll see the average intake of various macronutrients and food groups broken down by low, low-medium, medium-high, and high acid load quartiles. Intakes were very different across quartiles, particularly comparing the lowest and highest quartiles. Let’s look at some of them and consider how they might relate to the risk of diabetes:
The high-acid quartile ate the least magnesium. Magnesium intake has been strongly, consistently, and inversely linked to type 2 diabetes. A 2011 meta-analysis spanning 13 studies and over half a million subjects found a significant inverse association between magnesium intake and type 2 diabetes risk (in a dose response relationship, so the more they ate the less diabetes they got); an earlier meta-analysis had similar results. Just recently, a study found that higher magnesium intakes were associated with lower fasting glucose and insulin resistance, prompting the authors to posit that magnesium intake can protect against progression from pre-diabetes into full-blown type 2 diabetes. Another recent study confirmed these associations, finding that a high magnesium intake predicted reduced insulin resistance.
The high-acid quartile ate the least potassium. Potassium intake may be linked to type 2 diabetes as well, but it’s not clear. A recent review of the inconsistent evidence makes some interesting observations, however: induced hypokalemia (potassium deficiency) causes glucose intolerance in humans and repleting potassium reverses it.
The high-acid quartile ate the fewest vegetables. Although the evidence is somewhat unclear, vegetable intake is usually associated with a reduced risk of type 2 diabetes, particularly root vegetables and leafy greens. One study found that a great quantity and variety of vegetable intake led to a lower risk of type 2 diabetes. And once you have type 2 diabetes, green vegetable intake is associated with improved HbA1c scores and lower triglycerides. Plus, vegetables are the best source of protective nutrients like magnesium.
The high-acid quartile ate the fewest fruits. Certain fruits, particularly ones with antioxidant-rich skins like blueberries, plums, apples, and grapes, are associated with a reduced risk of type 2 diabetes despite the sugar content.
The high-acid quartile drank the least coffee – about half as much as the lowest quartile. Coffee is one of those consumables that everyone knows is bad for you but which is actually linked to a number of health benefits, most prominently a reduced risk of type 2 diabetes. Across study after study, habitual coffee consumption is consistently associated with less type 2 diabetes. They’ve even run randomized controlled trials where coffee consumption protected against glucose intolerance, one of the first signs of pre-diabetes. This is almost certainly a factor.
The high-acid quartile ate the most calories, and high calorie intake (or, put another way, energy excess) may increase the risk of type 2 diabetes (if it’s not accounted for by activity or basal metabolism) by inducing insulin resistance at the cellular level. They were also the least active of all quartiles, which would contribute to the energy excess.
Although this wasn’t listed in the nutrient intake table, the high-acid load quartile would have also consumed the fewest plant polyphenols and antioxidants due to lower fruit, vegetable, and coffee intake. Plant polyphenols have been shown to improve glucose tolerance and homeostasis, which may help prevent type 2 diabetes and partially explain the protective effect of fruits, vegetables, and coffee on metabolic health. Grape polyphenols, for example, prevent fructose-induced oxidative stress and insulin resistance.
So, is it the acid load causing (or preventing) the diabetes? Or is the acid load merely a representation of the diet which in turn causes (or prevents) the diabetes? Heck, it may even be that the diabetes is causing kidney disease, which in turn leads to acidosis. We don’t know for sure from this study. As the authors write in the discussion section, “this is the first prospective study to evaluate the risk of type 2 diabetes associated with scores reflecting the acid load of the diet.” What we do know is that many aspects of the overall dietary pattern of the high-acid quartile, like low magnesium, potassium, coffee, and produce intake, are consistently linked to type 2 diabetes across multiple studies. For now, that seems to be where the strongest evidence lies.
Eat your vegetables and fruits. Get your micronutrients and plant polyphenols. Drink your coffee. Try not to eat so much food that you gain weight and overload your cells’ ability to handle the energy. Exercise consistently and intelligently.
Dear Carrie: Is Homemade Baby Food Safe?
I actually do not have any children of my own… but as someone who is part of a local farm’s veggie & protein CSA, and is very passionate about “knowing where my food comes from”… this subject really disturbs me.
I’ve recently been warned via mass Facebook update about the risk of making baby food at home: “In 2005, the American Academy of Pediatric released their advisory for homemade baby food. They stated, ‘Infants fed commercially prepared infant foods generally are not at risk of nitrate poisoning. However, home-prepared infant foods from vegetables (eg, spinach, beets, green beans, squash, carrots) should be avoided…’”
Can you please provide your input? This seems like a marketing ploy… I can’t see how commercially prepared is better?
The worry with too much dietary nitrate in baby food is that it can lead to something called methemoglobinemia, or excess methemoglobin levels. Methemoglobin binds oxygen and prevents it from getting to the tissues in our body. In normal conditions, methemoglobin levels are extremely low and cause no problems. With too much nitrate in the baby’s diet, however, rapid conversion to nitrite in the immature intestines causes methemoglobin levels to jump 1000-fold, leading to tissue hypoxia (lack of oxygen). This is bad, particularly for a cute little helpless baby.
So, watch out for nitrates, right?
I found the Facebook post to be extremely misleading. I went ahead and took a look at what the AAP actually recommends. Nitrate only poses a problem for kids of a certain age. At six months, intestinal conversion from nitrate to nitrite is greatly reduced, making dietary nitrates much safer. It’s right there in what the AAP actually wrote back in 2005: “the intake of naturally occurring nitrates from foods such as green beans, carrots, squash, spinach, and beets can be as high as or higher than that from well water, these foods should be avoided before 3 months of age.” They go on to say that this shouldn’t be an issue anyway since “there is no nutritional indication to add complementary foods to the diet of the healthy term infant before 4 to 6 months of age.” Since you shouldn’t even be feeding complementary foods before 3 months, this isn’t a problem. In fact, I breastfed Devyn for two years and Kyle for a year. They were given only breast milk for the first six months of their lives.
Total non-issue, unless you know people who are pureeing these foods for their newborns under six months. That can be an issue. In a recent study looking at a group of homemade food-associated infant methemoglobinemia cases, the biggest risk factor was homemade food that was made too far in advance. Food made 24-48 hours before the kids ate it had an odds ratio of 17.4 and food made more than 48 hours before consumption had an OR of 24.9, most likely because the nitrate was converting to nitrite in storage (which, remember, is what does the damage). Other risk factors included breastfeeding (!), chard, and borage.
When I was introducing solid food to Devyn and Kyle, I usually made my own at home, (and vegetables were probably the last things I introduced). Even though I eat a ton of vegetables now, I do find many children tend to dislike vegetables, and you shouldn’t try to override their natural revulsion because it may be in place to keep them away from plant toxins they haven’t developed a defense for. It’s probably not a great idea to introduce chard, borage leaves, and spinach too early. Try meat, lightly cooked egg yolks, ripe fruit. My children enjoyed, peas, carrots and sweet potatoes. Those are way more digestible (and enjoyable). Besides, if you are feeding complementary foods, ones made at home are way more nutrient-dense than store-bought purees.
That’s it for today, folks. Let us know what you think in the comment board!