A few years back I read an article by a very well known nutrition expert on the effects of altering one’s diet towards limiting net-acid producing foods while simultaneously increasing net-base (alkaline) producing foods. I was honestly shocked to see this person place serious clout on the “alkaline-diet.” The essential summary was that the typical Western diet is the cause of all things wrong within the body (disease, weight gain, bad breath, you-name-it) because it results in a net acid load, and this places unnecessary stress on the body’s homeostatic mechanisms to release and deliver alkaline (base) forming counter-molecules to neutralize the acids and therefore maintain total body pH balance.
So, in theory, in order to maximize both health and athletic performance, all you have to do is get 80% of your total calories from non-grain carbohydrate sources (primarily fruits and veggies) while limiting your protein and fat intake to the remaining 20% of your total calories (about 10% each). The claim is that proteins and grains result in a net acid load which can contribute to all sorts of health issues, but that this net acid load also results in weakening of bones, limitations in strength, power, and endurance, as well as serious restrictions in post-training recovery. The evidence does not support these claims, by the way, and I am still surprised that those who support this type of diet can completely ignore all the research showing protein and fat at these low levels having negative effects on athletic adaptations and performance. There are very obvious reasons why so many nutrition professionals in the realm of sport performance find it very hard to take the primary tenants of this diet seriously, but I think it is wise to dig into the research to see if there is any potential athletic or health benefit before writing it off as nutritional quackery. So, what do we actually know about how the body regulates pH?
Well, the pH scale works a little something like this: A pH of 0 to 6.9 is considered acidic, a pH of 7 is considered neutral, and 7.1 to 14 is considered basic. This is important because your saliva, blood, stomach contents, and urine all have different pH levels simultaneously, which makes the entire idea of eating specific foods to alter your body’s pH problematic. Saliva, for example, has a pH around 5.6-6.9, making is slightly acidic. This is because digestion begins in your mouth, and the enzyme that begins to breakdown food, amylase, functions optimally at this pH range.
So, if you are eating “alkaline” food, simply chewing your food starts the processes of making it more acidic. From there, food enters your stomach where it is hit with stomach acid (hydrochloric acid), which is an extremely strong acid ranging from 1.5-3.5 on the pH scale. So, whether you are eating something very acidic or something quite basic, it becomes very acidic within your stomach, and thus enters your small intestine acidic. This is where some promoters of the alkaline diet claim that the pH of blood can be affected by one’s diet. The issue with this claim is that there are multiple mechanisms within your body to maintain blood pH right around 7.4 (slightly basic). These mechanisms keep your blood from shifting either way on the pH scale, because a change in either direction (below 7.0 and above 7.7), results in death. Promoters of the alkaline diet rarely address the concern many scientists have previously brought up regarding blood pH. Since it is unhealthy for blood pH to shift more than .4 in either direction, why demonize acids only? If you can actually alter your blood pH by eating net-alkaline foods, what if you eat too much net-basic food and shift your blood to an unhealthy basic level? I can’t find a valid response to this question, which should tell you something.
The primary mechanism to keep your blood pH at or around 7.4 comes via bicarbonate ions in the blood. If there is an increase in blood acidity (via digested food, exercise, etc.), bicarbonate ions buffer the acid, which results in the production of carbon dioxide, which then travels to the lungs and is expelled when you exhale. The kidneys then produce new bicarbonate ions and this process can continue as needed. Urine pH, in contrast to blood pH, can range to a much greater extent, and can be easily influenced by the net pH of the foods you eat. Keep in mind that salivary pH, blood pH and urine pH are completely independent of one another in healthy adults, and therefore testing your saliva or urine to see if you are net-acidic is not a valid or reliable test of total body pH.
The story doesn’t end here, though. We all know that your body simply functions better when we eat more fruits and veggies. Is it because fruits and veggies are net-alkaline? Or perhaps is it because of the millions of vitamins, minerals, phytochemicals, and phytonutrients found uniquely in fruits and vegetables that our bodies use to keep our cells in tip-top shape? Funny enough, we don’t even know all the reasons why fruits and veggies are so good for us, but there is no doubt that they help us in millions of ways. I have no doubt that one reason vegetables are practically beneficial to us is because they do contain bicarbonate ions that may assist with acid buffering, but we must remember that this is not the only reason. It is simply 1… of literally millions.
We cannot fragment away the pillar that muscle protein synthesis is the cornerstone of adaptation and recovery, and that protein, therefore, is a vital part of performance and recovery. If maximizing both athletic performance and recovery is a priority, then excluding, or severely limiting, any macronutrient from one’s diet should not be something done on a whim.
We are responsible to evaluate dietary claims against what we know to be sound science. So hit your caloric need, hit your macronutrient goals, and eat as many fruits and veggies as possible. Make sure you are getting enough calories to fuel training and provide enough energy to be able to “afford” athletic adaptations.
- Shoot for a minimum of 1 gram of protein per pound of body weight every day so you can stimulate muscle protein synthesis, repair from the damage of training, and drive athletic adaptations.
- Shoot for at least 25% of your total calories from fat so you can maintain proper anabolic hormone levels.
- Use the rest of your calories to get as much nutrient dense fruits and vegetables so you keep your body’s health and wellness your number 1 priority.
That’s the recipe to get the best of everything.
About Kevin Kuhn
Kevin Kuhn, M.S.Ed., CSCS, MFS is a Kinesiologist and Sport Nutrition Coach in Dallas, Texas. Before moving to Dallas in 2012, Kevin was the head strength & conditioning coach for the Indiana Invaders professional running club in Indianapolis, Indiana. Kevin specializes in athletic performance with great interest and experience in running-specific strength & conditioning, corrective exercise, and exercise and sport nutrition. Kevin has been certified by the National Strength & Conditioning Association as a Certified Strength and Conditioning Specialist (CSCS) and as a Master Fitness Specialist by the Cooper Institute.
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