The North American diet (yes, even the diets of health-conscious North Americans) is often a very acidic one. From most protein sources (even the lean ones) to many dairy sources (especially cheeses) to grains (even the unprocessed ones), many of our dietary staples produce a net acidity in the body, overwhelming the amount of bases we take in daily. And it’s this imbalance between acid and base that can cause some serious long term health and physique problems.
I know, I know – some docs will tell you this is absolute baloney. Well, perhaps they also think that journals like the Journal of the American Dietetics Association, the Journal of Clinical Endocrinology and Metabolism, the American Journal of Physiology, the American Journal of Clinical Nutrition and the European Journal of Nutrition are also full of crap. What’s the link? Well, these journals and more have published scientific papers detailing the importance of the dietary acid/base balance.
So, the bottom line is, if your doc tells you that the dietary acid/base balance isn’t important, you need to find a new doctor immediately! It is important – and in this article, I’ll tell you why…
The Acids and Bases We’re Eating
When a food is ingested, digested and absorbed, each component of that food will present itself to the kidneys as either an acid-forming compound or a base-forming one. So remember, when we eat, it’s the broken down chemicals in our food that determine how much acid or base will enter our bodies.
I make this last point as it’s easy to confuse acid foods with acid loads. Take an orange, for example. Seems like an acidic food, right? Well it is, outside the body. However, once it’s digested and absorbed, the digested and absorbed orange chemicals present themselves to the kidneys as a base load. This is the case with most fruits and veggies. So don’t confuse a food’s acid/base status outside the body with what it does inside the body.
Now, when the sum total of all the acid producing and the base producing micro and macronutrients is tabulated (at the end of a meal or at the end of a day), we're left with a calculated acid/base load on the body. If the diet provides more acidic components, it will obviously manifest as a net-acid load on the body. And if it provides more basic components, it will obviously manifest as a net-base load on the body.
Since I already noted that a net acid load is bad, let’s discuss why.
Every cell of the body functions optimally within a certain pH range (pH is a measure of the acidity or alkalinity of the body). In different cells, this optimal range is different; however, the net pH of the body has to remain tightly regulated. One common problem with most industrialized societies is that our diets produce what's called a "low grade chronic metabolic acidosis." In other words, the PRAL (potential renal acid load – a measure of the amount of acid being introduced through the diet) of our diets is high, and this means that we're chronically in a state of high acidity.
While there are a number of disease states that induce severe metabolic acidosis, we're not talking about that much acidity here – we’re simply talking a sub-clinical rise. Therefore, your doc probably won't notice the problem. In fact, because the acidity of the body is so tightly regulated, no one will likely notice the problem, at least not right away. But that doesn't mean you're in the clear. Your cells will recognize the problem.
So what's wrong with this low-grade chronic metabolic acidosis?
Well, since the body must, at all costs, operate at a stable pH, any dietary acid load has to be neutralized by one of a number of homeostatic base-producing mechanisms. So, although the pH of the body is maintained and your doctor visits turn out fine, many cells of the body will suffer. Here are some of the most severe consequences of your body's attempt to maintain a constant pH in the face of an acidic environment:
- Hypercalciuria (high concentrations of calcium in the urine). Since calcium is a strong base and bone contains the body's largest calcium store, metabolic acidosis causes a release in calcium from bone. As a result, osteoclastic (bone degrading) activity increases and osteoblastic (bone building) activity decreases. The net result of these changes is that bone is lost in order to neutralize the acidic environment of the body. The calcium that was stored in the bone is then lost in the urine along with the acid it was mobilized to neutralize. This creates a negative calcium balance (more calcium is lost from the body than is consumed) and bones get weak.
- Negative nitrogen balance (high concentrations of nitrogen in urine). Glutamine is responsible for binding hydrogen ions to form ammonium. Since hydrogen ions are acidic, glutamine acts much like calcium to neutralize the body's acidosis. Since skeletal muscle contains the body's largest glutamine store, metabolic acidosis causes muscle breakdown to liberate glutamine from the muscle. The amino acids from this muscle breakdown are then excreted, causing a net loss of muscle protein.
In addition to bone and muscle loss, other consequences of acidosis include:
- Decreased IGF1 activity
- GH resistance
- Mild hypothyroidism
Yes, our bodies do have buffering mechanisms (the bicarbonate system is the big one) to deal with excess acid such as the acids produced during exercise and dietary acid loads. However, these systems can get overloaded, and as discussed above, the bones and muscles suffer.
Interestingly, low-grade metabolic acidosis seems to worsen with age. Many have speculated that this is due to an age-related decline in kidney function. With a decrease in kidney function, we get a decrease in acid excretion. Of course, osteoporosis and muscle wasting are unfortunate consequences of aging. While it's too early to tell, perhaps some of the bone and muscle loss evident as individuals get older is a result of diet-induced acidosis. This means that employing a few simple acid-base strategies may help slow osteoporosis and sarcopoenia.
Who Is At Risk?
So the big question is, who’s at risk? Recently, Sebastian and colleagues compared the pre-agricultural diet of our ancestors to the modern North American diet. After evaluating the two diets for what they call NEAP (net endogenous acid production, essentially the same measure as the PRAL above), a -88mEq (milliequivalents) /day acid load characterized the pre-agricultural diet while the modern diet was characterized by a +48mEq/day acid load. What this means is that our ancestors evolved eating a diet that produced more alkaline/basic components versus acid components. However, modern people are eating a diet that produces high acid components and therefore very different from what we evolved to eat. As a result, our modern diet is responsible for what the authors have called a "life long, low grade pathogenically significant systemic acidosis."
So how have we gotten so far off track? Well, the shift from net base producing foods to net acid producing foods comes mostly as a result of displacing the high bicarbonate-yielding plants and fruits in the diet (again, fruits and veggies produce lots of bases) with grains (again, these produce lots of acids). In addition, most of our modern, energy dense, nutrient poor selections are also acid forming. Finally, high protein animal foods tend to be acid producing as well.
If you're now wondering how your diet stacks up, check out the online acid-base forum: www.acid-base.de. There you’ll be able to calculate your PRAL and determine how much of an acid or base load your body is under. Further, if you’re ingesting too many dietary acids, as most people are, here’s what you can do:
- Add more vegetables, regardless of the final tally. Everyone can always benefit from more vegetables in the diet. Many bone specialists are now recognizing that the most effective way to improve bone health isn’t to add dietary calcium. It’s to eat lots of fruits and vegetables. Vegetables, in addition to all of their other benefits, are powerful acid neutralizers.
- If you're eating a big meal that's going to be a net acid producer (such as one that contains a large amount of protein and/or grains) and don't want to add more basic foods, consider adding a small amount of glutamine to this meal. Exogenous glutamine supplementation has been shown to neutralize acidosis.
- A cheaper alternative to glutamine supplementation is either sodium or potassium bicarbonate supplementation. You can add sodium bicarbonate (in the form of baking soda) to your beverages including your protein shakes, which probably are a bit on the acidic side (see milk above). A small two to five gram dose of baking soda would be sufficient to neutralize the shake. But be warned – this tastes pretty bad. An alternative to baking soda is Alka-Seltzer.
- Adding sodium to foods can increase the base potential and reduce the acidity of the meal, although a high salt diet isn’t necessarily recommended, especially for those with high blood pressure.
In the end, although few individuals in the exercise nutrition world are discussing this issue, it remains an important one. Employing a few simple strategies to neutralize your high-acid diet may mean the difference between chronic low-grade acidosis — and the associated muscle wasting, bone loss and altered hormonal profile — and a healthy, alkaline diet. So make sure you’re dietary acids are covered!