Nutrition Myths

SUMMARY

  • The alkaline diet’s core claims are not backed up by scientific evidence, but rather disproven by good quality studies.
  • Alkaline diet is healthy, since it excludes unhealthy foods and promotes whole and fresh foods.  However,  its health benefits have nothing to do with its claims.
  • Alkaline diet may contribute to a risk reduction of developing cancer, purely because it promotes eating whole vegetables and fruit and restricts processed foods and added sugars, but not because of the alkaline environment it claims to create.
  • The urine pH test only measures the acidity of the urine and not the body’s alkaline balance which can be determined only by using blood samples.
  • Acid-forming diets can cause osteoporosis if combined with a calcium intake consistently below the recommended daily value. Increasing the calcium intake may improve the bone health.
  • Acidic foods (foods with low pH) don’t necessarily influence the acid-base balance of the urine. Urine’s pH depends rather if they are acid-forming or base-forming foods.
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Alkaline diet – myths and facts based on science

Does alkaline diet work?

The core claim of the alkaline diet is that some foods rich in protein or phosphorus, such as meat, grains and dairy products leave behind an acid-ash residue that creates acidic environment in the body. This leads to serious health problems such as cancer or osteoporosis.

Additionally, the alkaline diet consists mainly of natural and fresh food, mostly of plant origin. This diet categorically excludes any processed or fried foods, including flour based products, processed meat products or products with added sugar.

Any diet, low in sugar and  made up of whole, unprocessed, fresh foods will improve your health!

However, the actual core claims, made by the alkaline diet supporters about the advantages of this diet such as being protective against cancers, bone loss and promoting overall health are not backed up by science.

Contrary to what is advocated by its supporters, there are no good quality studies showing that the level of acidity of the ash in foods has an impact on health.

Alkaline diet started with the acid-ash hypothesis, followed by unproven health claims of the alkaline foods and with additional supporting theories to make the initial myth sound like a fact.

MAIN POINTS

  • Alkaline diet may be beneficial because it promotes whole and fresh foods and excluded processed foods and sugars.
  • These benefits have nothing to do with alkaline foods, which is the core claim of the alkaline diet promoters.

Alkaline diet related myths

NOTE: Acidic foods are not the same as acid-forming foods and have nothing to do with urine pH.

Acidic foods are those foods that have a pH measure in their original state, before consumption.

Acid-forming foods are those that contain net acid-forming minerals. They make the urine pH more acidic, but not the blood pH.

Acidic foods may be base-forming (e.g. lemon) with no impact on the acidity of the urine or blood. (read more..)

The following is a summary of the most common myths and misconceptions that alkaline diet is based on: 

MYTH 1: Our ancestors’ diet was predominantly alkaline, and the modern day diseases are a result of an acid ash diet.

The most recent studies show that only about 50% of our ancestors were on an alkaline diet and 50% on an acid-ash diet. Since modern-day diseases were virtually not present in those times, it is logical to conclude that the acid-ash diet cannot be blamed for modern day diseases.

Modern day diseases are more likely a result of a combination of factors, such as lack of activity, smoking, pollution, processed foods, high carbohydrate consumption, pesticides, pollution, drugs or chronic stress. (read more..)

MYTH 2: Urine pH measures the body alkaline balance (body pH).

A common confusion among the alkaline diet enthusiasts is that when urine pH tests come out to be acidic, then it is assumed that the body has an acidic environment. This is not correct.

Urine pH measures the net ash that is excreted by the body.

Blood pH test measures the alkaline body balance.

Urine and blood pH tests are not the same and measure two different things. (read more..)

MYTH 3: Acid-forming or base-forming foods affect blood pH/body acidity.

Acid-forming foods or base-forming foods only change the urine pH. Blood pH remains unchanged thanks to a system of buffering inside the body. One of the buffering factors, the kidneys, makes the urine change its pH.

MYTH 4: Acid-forming foods cause leaching of calcium from the bones and lead to osteoporosis.

Bones may release calcium to balance the blood pH when there is a large (abnormal) drop in blood pH caused by serious medical issues or a diet low in calcium. However, bones do not release calcium as a result of consuming net acid-producing foods. There are other buffering systems that take care of that before calcium gets released from the bones. (read more..)

It has been shown that a net acid-producing food diet causes mineral bone loss and leads to osteoporosis only if the calcium intake is below the recommended amount. A diet rich in calcium and proteins has proven to be optimal for bone health.

A good example of foods popularly considered as acid-forming, that are protective against osteoporosis is milk and dairy products. (read more..)

MYTH 5. Acid-forming foods cause cancer.

This myth relates to the specific claim that cancer’s preferred acid environment results from the diet.

Acid-forming foods do not change the blood or the extracellular fluid pH. The acidic micro-environment in which the cancer thrives is created by the cancer’s cells as a result of the rapid cell multiplications and, consequently, the need for more glucose. Whether fresh vegetables and fruits protect the body from the cancer cells proliferation is another matter. (read more..)

Does the urine pH test measure the body’s alkaline balance?

Urine and blood acidity is often confused by alkaline diet supporters.

Many online lay-men and sources believe that body acidity (or blood acidity) is the cause of many health issues and to test it you can use urine or saliva.

Irrespective whether that theory is correct or not, this myth is busted as a urine pH test is not an indicator of the alkaline balance in your body.

Blood pH is tightly controlled by a number of mechanisms in the body and must stay in equilibrium.

Only by using blood samples, it is possible to determine the blood pH.

Please note, however, that testing blood pH is useless, unless you have some related underlying medical condition. Dietary changes will not cause your blood pH to fluctuate. 

One of the ways that this equilibrium is controlled is by removing through the urine the excess of ions from the system by the kidneys. These ions, depending on their charge, can make urine more or less acidic.

Therefore, when you measure urine pH you are measuring what was excreted from the body in order to maintain that equilibrium rather than the acid-alkaline balance of the blood. (1, 2, 3, 4)

MAIN POINTS

  • The urine pH test only measures the acidity of the urine.
  • The acid-base level of the blood (pH of the blood or body’s alkaline balance) is calculated using blood samples and cannot be measured using urine or saliva.

Did our ancestors really eat mostly alkaline foods?

This myth question is related to the alkaline diet’s main argument, that alkaline foods promote health while acid-forming foods cause many modern day diseases. I will answer this myth from that perspective.

Accordingly to the supporters of the alkaline diet, our hunter-gatherer ancestors consumed a diet  that consisted primarily of alkaline foods.

These claims are partially based on a 2002 study which estimated that 87% of humans before agriculture ate alkaline foods. (5)

One of the arguments that follows this result is that modern day diseases, such as cardiovascular disease, type 2 diabetes, obesity, various cancers, bone diseases and autoimmune diseases, were virtually absent in hunter-gatherer societies thanks to the alkaline diet.

Is this estimate and the resulting conclusion correct?

In the light of the latest results of most recent studies, the answer is no.

A recent (2010) large study that investigated 229 worldwide historically hunter-gatherer societies, revealed that  between 40%-50%, and not 13%, of the diets consumed by the pre-agriculture populations were net acid-producing. (6)

The most recent studies show that the diet largely depended on where each particular population lived, which, in turn, was determined by the latitude and the ecologic environment. (7)

Scientists found that in higher latitudes, the net-acid producing diet was more common. Above 40o, for example, the diet was predominantly net-acid producing while below that level they were more base-producing.

In addition to the latitude, the ecological environment was another important factor.

Acid-producing diets were more common in the northern areas (tundra and coniferous forest), temperate grasslands or tropical rainforests while other regions were base-producing.

MAIN POINTS

  • About half of the hunter-gatherer population were on an acid-ash diet and the other half were on an alkaline diet.
  • This contradicts recent theories that attributed the absence of modern society’s diseases in ancient societies to an almost exclusive alkaline diet.

Does a diet high in acidic foods make the urine acidic?

There are two concepts that are often confused which need clarification: acidic food and acid-forming food. (read more..)

While the acid-forming foods refer to its acid-ash contents and this concept is used in the controversial alkaline diet, the acidic foods simply relate to the pH of the food before consumption.

It has been well established that acid-ash absorbed from the diet makes the urine more acidic/less alkaline.

Urine pH is affected by acid-forming food and not by acidic food.

Here is how it works:

While acid-forming foods have proven to lower the pH of the urine, acidic foods don’t necessarily have the same effect. What determines the urine acid level (or urine pH) is “ash”.

Acid-ash causes urine pH to drop while base-ash causes urine pH to rise.

Acidic foods” may be acid-forming or base-forming depending on the net charge of the ash that it contains. (8)

For instance, acidic food which can be tested for its acidity (pH) outside of the body (before it is processed by the body) may contain high base-ash contents (alkaline/base-forming minerals). (8)

A good example is an acidic citrus fruit – lemon, which has pH of about 2 (neutral pH is 7).

After ingestion, lemon/lemon juice, which is highly acidic, is mixed with substantial amounts of more potent stomach acid with a pH of 1.5-3.6. (8, 9, 10, 11)

When the lemon/lemon juice reaches the intestine, the mixture of stomach juices and digested lemon is neutralized by bile secretions. It then gets broken down further until the remaining minerals (ash) get absorbed by the blood system.

As an analogy, imagine a gold panning technique where a wide, shallow pan submerged in water is shaken to sort gold from the gravel and dirt.

Gold is heavier than stones and dirt so it drops to the bottom of the pan and the rest of the material simply flows out of the pan.

Imagine that the gold which stays in the pan after all the stones and dirt have been removed represents the inorganic ash that stays within the body causing specific changes to the body’s acid-base balance.

The rest of the food is just dispersed and utilized in numerous body functions or excreted.

If ash is acidic, in order to prevent changes in blood acidity, the kidneys filter these acid-forming minerals and dump it in urine which is then excreted. The presence of these acid-forming minerals in urine makes it more acidic. (12)

Lemons, even though they are acidic in nature, when broken down and the organic material is removed, contain a majority of alkalizing minerals (base-ash). This residue causes the pH of urine to rise rather than drop, making it less acidic/more alkaline.

MAIN POINTS

  • The food acidity (the pH of the actual food) measured outside the body does not influence the acid-base balance inside the body or urine.
  • Acidic food indicates only that the pH of the food itself is lower than 7 and it can be either acid-forming or base-forming, depending on the ash contents of the food.
  • Acid-forming food contains substances which have the potential to change the body’s acidity. Removing acid through urine, by changing its pH, ensures that the body acidity stays constant.

Do acid-forming foods make urine more acidic?

NOTE: Two concepts: acidic food and acid-forming food are often confused. Urine pH is affected by acid-forming food and not by acidic food. (read more..)

The fact that acid-ash foods or acid-forming foods make urine more acidic is well-established by scientific studies. (13)

Unlike blood pH, the normal values of pH in urine range widely between 4.6pH and 8.0pH. However, it may differ slightly between laboratories. (14)  Fluctuations of the urine pH within this range indicate that the kidneys do their job making sure that blood pH stays within its narrow range.

How does it work?

After food has been digested and absorbed, the remaining ash makes an impact on the acid-base level within the body. A number of the body’s balancing mechanisms, however, ensure that blood pH remains at the optimal level.

One of these mechanisms is via the kidneys which remove through urine the excess of particles (ash) which could disrupt the delicate pH balance in the body.

As a result of the removal of ash through kidneys, urine becomes: (15, 2)

  • less alkaline/more acidic (in other words pH drops) when foods contain more acid-ash or
  • more alkaline/less acidic when foods contain more alkaline ash.

Calculating the amount of acid in urine can be even determined using mathematical formulas (such as Net Renal Acid Excretion NEA and Potential renal acid load PRAL), which use nutrient data from ingested foods. (16, 17)

Please note, however, that the above does not prove that the alkaline diet works which the myth question usually relates to.

MAIN POINTS

  • Acid-ash foods contain minerals which lower the pH of fluids.
  • The body has several mechanisms to counteract the action of the acid-ash from foods to maintain blood at its optimum acid-base level.
  • One of these mechanisms removes acidic substances through the urine via the kidneys,  which causes the urine to become more acidic.

Do acid-forming foods cause osteoporosis?

This myth relates to an ash-diet hypothesis which claims that some foods containing acid-forming substances, such as animal protein from milk or meat and some plant foods, cause blood pH to drop (become less alkaline).

It is, in turn, buffered by minerals released from bones. The loss of minerals from bones is supposedly responsible for osteoporosis.

This hypothesis was supported by a number of older studies which did not actually prove that an acid-forming diet directly causes a mineral bone loss.

It was assumed that an increased acidic environment in the body, an increase of calcium in urine and higher acidity of urine are indicators of mineral bone loss.

Many recent large studies (systematic reviews and meta-analysis) analyzed all currently available up to date studies and showed that there is not enough evidence to support this hypothesis and the assumptions of older studies, as explained below:

  • Higher amounts of calcium in urine in high protein diets are from higher absorption rather than mineral bone loss. (18)
  • Although there is a potential for the acid-ash diet to increase acidity in the body, blood pH does not actually change. It is quickly regulated by a number of mechanisms in the body such as the intra and extra cellular buffering system and kidney-urine acid excretion. Bones don’t play a part in the buffering of blood pH caused by an acid-ash diet on its own. (19, 20)
  • Higher acidity in urine is a result of an efficient buffering system of the kidneys removing extra acid-forming minerals and acids.

Although some studies show that there is a slight pH change with either a high protein diet or alkaline multi-mineral supplementation, these changes are not likely to affect the bone health or the acid-base balance of the body. In any case, there is still no scientific evidence of that.

MAIN POINTS

  • An acid-forming diet may cause mineral bone loss which leads to osteoporosis if it is combined with a calcium intake consistently below the recommended daily value.
  • High calcium intake while on a high protein diet (which is considered to be acid-forming) may be actually protective to bone health.
  • There is not enough evidence which shows that an acid-forming diet has its own negative effect on bone health.

Is alkaline diet cancer – protective?

One misconception about cancer is that its cells are acidic and/or cancer thrives in acidic environments resulting from an acid-forming diet.

The alkaline diet supporters claim that by increasing the consumption of alkaline foods, the environment becomes more alkaline, resulting in a reduction of the risk of cancer, the suspension of the cancer cell growth or even the elimination of cancer cells.

The following are the three main reasons why this theory is incorrect:

  1. What we eat does not change the blood pH or extracellular fluid and has nothing to do with the acidic environment around cancer cells. (1, 21, 22)
  2. Cancer cells have a neutral or slightly alkaline pH, but never acidic.

    However, outside the cancer cells, the environment may be slightly acidic. The acidity in the cancer cell environment is caused by a homeostatic mechanism in which the cancer cells expel hydrogen ions and lactic acid to maintain a constant neutral or alkaline pH within the cells.

    Therefore, cancer cells are actually causing the acidic environment around them. (23, 24)

  3. Cancer creates its own acidic environment in which it thrives. It’s rapidly multiplying cells increase glucose consumption, leading to an increased acid production.

    This excess of acid is then exported outside the cancer cells in order to maintain a near neutral pH. Meanwhile, in this process, the cells become more resistant to acid-induced cell toxicity.

    The increased acidic environment outside the cancer cells helps them to expand by invading other tissues not resistant to this acidic environment.

    The microenvironment created by cancer cells has a reduced circulation making it difficult for the blood to influence its pH. (25, 26)

    This biological fact is often omitted in the studies that try to prove that cancer is a result of the acidosis caused by diet.

MAIN POINTS

  • Diet does not change the body alkaline balance and cancer produces its own acidic environment, independently of the blood pH.
  • There is no doubt that eating plenty of vegetables and fruits and avoiding processed foods is cancer preventive, but for other reasons than their alkalinity.

NUTRITION FACTS VS NUTRITION MYTHS

You will find a summary of the most common nutrition myths and evidence-based nutrition facts here.

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Difference between acidic food and acid-forming food Acid-forming foods and acidic foods are unrelated and produce different effects on the body. Acid-forming foods may reduce the urine pH level, with no impacts on health. Acidic foods don't have an impact on the body's pH...
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