The Acid/Alkaline Debate
You have probably heard of the Acid/Alkaline Hypothesis, or of the Alkaline Diet.
Alkaline ash foods (vegetables and fruits leave an alkaline, high pH residue) have an alkalizing effect on the human body. Acidic ash foods (primarily proteins and starches leave an acidic, low pH residue) acidify the body. Note that this has nothing to do with stomach acid, and little to do with the acid content of the food since lemon leaves an alkaline ash.
The argument says that this acid residue requires buffering with alkaline output of the kidneys. When kidney function decreases with disease or age, alkaline calcium from bone and muscle are required in increasing amounts. The results include osteoporosis and muscle loss, along with other negative consequences.
Evidence is available both pro and con, and it truly seems a mystery as to which argument is correct. Health websites promoting "evidence-based" health information from a medical perspective (example here) and even respected natural health websites (e.g. here) reject the hypothesis.
I think the argument is sound. See what you think....
A good starting point in examining this hypothesis is recognizing the body’s constant striving for balance, and its ability to compensate when balance is threatened.
There are many examples of the body’s ability to offset imbalances.
- a person starts a diet (a self-induced famine), and the body’s metabolism slows to conserve reserves by burning less fuel
- Excess blood sugar is balanced by increased production of insulin
- A temperature rise is balanced by production of sweat to cool the body
So what happens when we have an acidic ash diet, the modern emphasis on acidic proteins and starches combined with a much lower amount of alkalizing vegetables and fruits? (Note that fats are pH neutral.) Yes, the body compensates.
But when it cannot compensate from first line resources, these are 6 likely results of a high acid diet:
- Bone loss (osteopenia, osteoporosis)
- Muscle loss
- Kidney stones
- Insulin resistance
- Metabolic syndrome
- Increased pain sensation
Remember that protein (acid) and Fat (neutral) are for building, and vegetables and fruits (generally alkaline) are for cleansing. We need some kind of balance of both.
There are numerous conflicting studies, but you can see a couple here (for the theory) and here (against). The “Look Inside” feature on Amazon for the book, Metabolic Acidosis, makes the book look like a well-documented case for the theory: “At least some of the retained H+ (acidity) is buffered by bone…” (p. 3). There is a great deal of information supporting the hypothesis.
And this study in the British Journal of Clinical Nutrition makes a compelling argument for diet-induced acidosis and its effects on bone, kidney stones, and muscle loss, in spite of the obligatory concluding words, “requires further investigation.”
The previous article starting this series followed a meal down the alimentary canal, the digestive tract. The drawing showed the pH of the organs along the journey. We can measure saliva and urine pH with a test strip. We get only a general idea of the pH of other fluids in the body – the extracellular fluid that is the ocean in which our cells and organs swim.
The pH of what enters the body has an effect on different tissues contacted. The body must deal with the overly acid or overly alkaline intake because of the food’s interaction with tissues on the journey.
The blood must maintain a pH of about 7.35-7.45 (slightly alkaline). The Acid/Alkaline Hypothesis includes several arguments as to why we must choose more alkaline ash foods (e.g., green vegetables and most fruits), or risk damaging results from an overabundance of acidic foods (e.g., protein, grain, and carbohydrates):
- The body will pull alkaline calcium from the bone, (osteopenia to osteoporosis), and from muscles (sarcopenia)
- The body will pull alkaline sodium from the bile, leaving a sludge that may lead to gallstones (Morter, pp. 70-72)
- Acidic pH of extracellular fluid (as from acidic waste from diet) results in urine that will be so acidic that it burns tissue, so the kidneys produce a carbonate or ammonia buffer as long as they are able
- As kidney function declines with age (beginning at about 30 or so), the body increasingly relies on calcium in bones and muscle, or sodium in bile
Why are postmenopausal women more prone to osteoporosis than men, who are associated with a higher protein diet? This study answered the question by pointing out that women of age 45-54 with “a lower dietary intake of acid-producing foods correlated with greater spine and hip bone mineral density, as well as greater forearm bone mass.” Two other confirming studies are quoted in this reference, also. The acidic diet matters for women, too.
This meta-analysis contradicts the studies just mentioned, saying there is no correlation between dietary protein and osteoporosis. There is no mention of whether the change in dietary protein altered the pH. But perhaps this contradictory conclusion just forces us to examine our own unique situation.
Estrogen deficiency in women (men need both estrogen and testosterone for bone health) is associated with increased osteoclast numbers. Osteoclasts break down old bone cells while osteoblasts build new bone cells. An excess of osteoclasts contributes to loss of bone density. The amount of estrogen and the balance of estrogen and progesterone are important for women.
A diet (and digestive capability) and lifestyle lacking in Vitamin D, calcium, magnesium, and exercise, or that includes smoking, excess alcohol, carbonated drinks, or steroids increase the probability of bone health deterioration. These factors include the lack of 2 alkaline minerals (calcium and magnesium) and an excess of 2 very acidic drinks, alcohol and carbonated beverages (phosphorus). Is this coincidental?
Many people have great success recovering from chronic diseases by switching from the extremely acidic standard American Diet to an extremely alkaline diet. The sharp change in course correction is necessary as the accumulated debris of the acidic diet requires a thorough cleaning by the alkaline diet. At some point, we must return to balance.
The problem of an acidic diet is compounded by the aging process as the kidneys ability to produce alkalizing bicarbonate declines and the same acidic diet requires the buffering calcium to come from bone and muscle. Loss of bone mass and muscle mass are signs of aging, but these are accelerated by the acidic American diet.
Note that we also are prone to lose digestive integrity as we age, as well as to exercise less, and these are contributing factors.
Research shows that people long ago generally had much more alkalinity in their diets, depending on the higher fiber fruits and vegetables with less dependence on the lower fiber protein and the few starches available.
The question of populations with a naturally high protein intake, such as the Masai in Africa, are clouded by lack of information prior to the disruption of their traditional diet and lifestyle. Weston A. Price found six cattle-keeping tribes with excellent teeth and no cavities. He also found good health (but less height and a few cavities) in tribes with primarily vegetarian diets, as well.
The best health belonged to a tribe that ate fish and cereal grains (prepared much differently than ours!). They were not as tall as the cattle raisers, but better proportioned and more muscular.
These examples show that a lifestyle (including diet and exercise) that has maintained a culture for many generations has allowed the body to adapt. We see this in the mixed ancestries and diverse biologic capabilities of people across the globe.
The diet that works for the individual – vegan, vegetarian, omnivorous, or high protein – is the appropriate diet. Looking at the long term effects of a diet, or the need for short term changes to correct imbalances, will ensure long term health. We must monitor and adjust course, as necessary, as with any journey.
The highly acidic western diet has been blamed for our chronic diseases, such as coronary heart disease and osteoporosis among the others. Were we to switch to a highly alkaline diet of processed foods, we would fare little better. Whether acid is the culprit or merely an accessory to the crime seems less important than eating a balanced diet of whole foods in a spirit of peace and thankfulness.