Our coral reefs are dying. The main culprit appears to be acid in our oceans- a slow downward creep in pH as ocean water absorbs increasing amounts of carbon dioxide. As carbonic acid builds, the ocean water’s pH decreases, and the acid stress leaches minerals from the reef, which is mostly calcium carbonate.

Your bone is comprised of calcium, magnesium, and phosphorus- alkaline minerals. Does your bone act like the reef if your fluids become more acidic? Is the story similar? Proponents of an alkaline diet make this claim- that not only does diet affect your internal pH, but also that acidity can damage your bones and lead to other chronic illnesses like cancer.

But, extraordinary claims requires extraordinary evidence, and in the case of the alkaline diet theory, the evidence is less than extraordinary. Read on to learn more about the myth of the alkaline diet- and why so-called acid-forming foods are the least of your bone-health concerns.

What is the Alkaline-Ash Diet?

Here is the position of the alkaline diet: Your body gets energy by burning foods for fuel. The remaining ash is either acidic or basic (alkaline). Choosing more alkaline-ash foods than acid-ash foods (about a 3:1 ratio) helps promote a balanced internal environment. This basic shift balances the stressors in daily life that produce acid in your body, reducing the work you must do to maintain pH balance.

Acid-ash foods include most proteins, phosphate, and sulfur (meat, poultry, fish, dairy, eggs, grains, and alcohol). Alkaline-ash foods include the minerals calcium, magnesium, and potassium (fruits, nuts, legumes, and vegetables). Neutral foods include fats, starches, and sugars. According to this theory, you can see the results of your food intake reflected in your urine pH, but the food choices you make also affects the pH of other fluids, like blood and extracellular fluid.

The fear: Don’t eat enough alkaline foods? Expect the minerals in your bones to be used to buffer acid and support pH balance, which will wear down your bones.

Let’s Examine the Evidence

Claim: Changes in urine pH are evidence that different foods have different effects on pH in the body overall, and that those changes matter to the pH of the environment your cells are in.

Examination: Yes, the food you eat changes the pH of your urine. But what does that actually tell you? It tells you what you ate recently—Which you already knew. But, here is the part the alkaline dieters are not telling you. Your urine pH changes so that your blood pH doesn’t have to. Your blood pH is kept in a tight range, and will not change much based on your food consumption. Extracellular fluids (outside) and intracellular fluids (inside) of your cells cannot drastically alter their pH or cells won’t function properly. Other factors change your urine pH as well, such as fasting, exercise, or medication use. Finally, there are cultures all over the world, both modern and historical, that do not suffer from higher rates of cancer, diabetes, or osteoporosis and consume a mainly acid-ash diet.

Besides, your body isn’t all about that base. Acids are actually essential building blocks of life…think EFAs (essential fatty acids), amino acids and even your DNA (deoxyribonucleic acid) You actually have a range of pH in different tissues. Your saliva is slightly alkaline to protect your esophagus from the acid in your stomach. Your stomach contains strong acid to start digesting protein, kill invading pathogens, and boost your absorption of several key nutrients, including B vitamins and minerals like iron, calcium, and zinc. Your blood is almost a neutral pH- it is just a tad alkaline. Urine pH varies day to day, as we will discuss.

Urine Luck If You Love Protein

Claim 2: Urine pH can accurately reflect your blood pH.

Examination: Your urine differs from the blood and extracellular fluids surrounding your bones. Yes, many studies have been done of the “potential renal acid load” (acid level in urine after eating) associated with different foods. But consider that a major function of urine is to change its own pH to help the pH of the blood it is filtering stay in a critical range. Urine contains urea- a molecule complexing two basic ammonia molecules into a pH neutral urea molecule for excretion. Your kidneys use some phosphate and lots of bicarbonate to stabilize your blood pH. Yes, urine pH must be within a stable range to avoid burning your urethra as it leaves you, but in general, your urine pH can very much more wildly than the pH of your blood as one compensates for the other.

As anyone who has worked in a hospital knows, major shifts in your blood pH can be fatal. Your metabolism relies on chemicals that function in a tight pH and temperature range. Your kidney excretes water, minerals, buffered acids, and toxins while your lungs exhale carbon dioxide produced in the kidneys. Feedback loops usually maintain stable blood pH, so you do not risk death at every high protein, low vegetable meal.

Make No Bones About It

Claim 3: Choosing more acid-ash than alkaline-ash foods will make your blood acidic. To buffer this acidity, your body uses the minerals in bone (like calcium), which can lead to osteoporosis.

Examination: Sorta- but not really. This claim misunderstands what your kidneys, lungs, and parathyroid gland do. Mostly, your kidneys use bicarbonate to support your pH balance. Also, phosphate, found in bone, is used to make phosphoric acid, found in urine. But you have an entire parathyroid gland to tightly regulate your blood calcium and phosphorus. This gland produces hormones that control making-and-breaking bone. Moreover, your blood passes through your lungs, which help regulate blood pH by exhaling carbon dioxide produced from in your kidneys. You exhale more carbon dioxide to remove excess acidity (like yawning); carbon dioxide is also used internally to make bicarbonate to buffer your blood. You also have a protein (albumin) that helps to buffer your blood. In short, calcium bone loss is not correlated with a high protein diet. Food for thought: a low protein diet may actually discourage your production of stomach acid and actually compromise your calcium absorption.

What does clinical evidence tell us? Multiple studies have confirmed that high protein intake provides collagen, phosphate, and other bone-building nutrition that is correlated with better bone health. Check out more on using protein for your bone health here.

But What About Cancer and Heart Disease?  

Claim 4: A common claim is that the alkaline diet supports an internal environment that is hostile to cancer cells and heart disease.

Examination: Many compounds in plant diets, such as polyphenols, are supportive of the fight against cancer. Other compounds support your immune system as it works to heal itself. But the alkaline diet as explained above will not change the pH of your blood and extracellular fluids in such a way as to kill cancer cells. Even if that were possible, your cancer-free cells would have just as much trouble surviving that pH shift. Researchers observed that cancer cells create their own acidic microenvironment for improved survival, but that acidity comes from the cancer cells- not the host body.

Evidence linking an alkaline diet to reduced blood pressure may be completely explained by other factors associated with eating more plant foods, such as increasing magnesium, calcium, and potassium intake. Poor kidney function is often responsible for challenges with maintaining stable blood pH, in this case, the “alkaline diet” could be a very supportive diet for someone with early to mid-stage kidney disease.

However, the bottom line is while the human body can benefit in many ways from eating high quality, properly prepared plant based (alkaline) foods – high quality, properly prepared animal based (acid) foods are equally beneficial. Whether a food is acid or alkaline is NOT what you should be focusing on for overall health. Instead, focus on food quality and becoming sufficient in your essential micronutrients (vitamins, minerals, fatty acids and amino acids) and leave the myth of the alkaline diet where it belongs – in storybooks.