The Alkaline Diet: Science & Health Benefits

Posted on Sun, 19 Oct 14

There is a lot of talk about so called “alkaline diets” ranging from elaborate lists of foods to avoid, to claims that an alkaline diet can reduce the spread of cancer. But how much of this is factual, and is there anything to the alkaline diet?

Alkaline diets have a long history of popular use and enjoyed a number of proponents at the turn of the 20^th Century. In fact, the founder of the macrobiotic diet Sagen Ishizuka (1851–1910) linked the equilibrium of acid and alkaline foods with the Chinese ideas of Yin and Yang (1). Move forward 100-years to the present day and popular books are still being published on alkaline diets with the general premise that eating more alkaline foods, and avoiding acid ones, can change the bodies acid-alkaline balance and deliver important health benefits.

In addition to popular books, there has also been a lot of scientific research into the influence of diet on acid-alkaline balance and its potential effects on human health in recent years. However, there is often an incongruity between popular alkaline diets and the science behind this concept. So with this in mind the following is a brief primer on the alkaline diet concept and separates some of the fact from fiction.

Diet-induced low-grade acidosis

So what is “acidosis” anyway? A popular conception of the alkaline diet is that it alkalizes your blood, however your blood pH is very tightly regulated at an alkaline pH of 7.35, which means this is not technically correct. Scientifically the concept of “acidosis” does not refer to marked alterations in blood pH but more correctly a dynamic compensatory response that occurs with an acid producing diet (2). In other words the term acidosis refers to a process, and not a change in blood pH to an acid state.

Food is linked to acidosis because it has the potential to place a more acid or alkaline “load” on your body depending on its nutritional composition, and subsequently your body quickly compensates or “buffers” this load to maintain a stable blood pH.

High-protein foods tend to increase the production of organic and sulfuric acids and increase acid load. These are mainly meat, fish, dairy and cereals, and the chloride in sodium chloride (salt) has an important acidic effect as well. On the other hand foods rich in potassium salts, like potassium citrate and malate, are metabolized to potassium bicarbonate and have a net alkaline effect. These are mainly fruit and vegetables (3). These nutritional characteristics can be reliably used to estimate the acid or alkaline effect of foods (see table 1).

Table 1: Acid or Alkaline Potential of Various Foods (4)

PRAL; Average potential renal acid loads.

But if your blood pH is not significantly altered, does this mean diet-induced acidosis is not worth worrying about? There are a few reasons why scientists think it does matter 1) it has been estimated that traditional human diets were much less acid producing than they are today, so in the same way we are not well suited to a highly processed diet we may not be suited to a predominately acid one 2) there is a trade-off for constantly countering the effect of acid foods, over time it may deplete your reserve of buffering alkaline minerals, especially in your bone, and tax your muscle, kidneys and endocrine system, and 3) there is compelling evidence to suggest that diet-induced low-grade acidosis is linked to important health effects over time (5,6).

Is diet-induced acidosis important?

There is increasing evidence to suggest that a more alkaline diet may be important for better health. Key areas include:

1. Bone health

Some, but not all, studies have suggested that a more alkaline diet or supplementation with alkaline minerals may improve bone health and prevent osteoporosis. Although a more alkaline diet may reduce the excretion of calcium from bone, the potential benefit may also be due more complex effects on cellular and hormonal bone metabolism (7-8).

2. Kidney stones

An acidic diet can increase urinary levels of citrate, a risk factor for kidney stones. In people with kidney stones a more alkaline diet predicted a lower incidence of stone formation, and supplementation with alkaline minerals was shown to reduce the risk of stone formation by 85% over a 3-year period (9,10).

3. Chronic pain

Local tissue acidosis can mediate pain through acid-sensing ion channels, suggesting an alkaline diet may be useful for pain relief. While there is limited research in this area one clinical study demonstrated important improvements in back pain with an alkaline mineral supplement (11,12).

4. Sacropenia

An alkaline diet may help prevent the age-related decline in muscle mass, also known as sarcopenia. In postmenopausal women supplementation with potassium bicarbonate neutralized acidosis and improved a measure of muscle breakdown (urinary nitrogen excretion). And a more alkaline diet has been associated with better lean muscle mass in older age men and women (13,14).

5. Heart disease

Diets higher in potassium result in robust reductions in blood pressure and risk of stroke (15). In accordance, a more alkaline diet has been associated with lower blood pressure in some studies (16-18). And a more alkaline diet has been linked with other cardiovascular risk factors, notably insulin resistance and chronic kidney insufficiency (19).

6. Cancer

There is experimental evidence to suggest that diet-induced acidosis may be a risk factor for cancer development, but this relationship is not clear and difficult to demonstrate in human research (20). And there are theoretical concerns about the safety of alkalization therapy (21).

7. Detoxification

Exposure to man-made environmental pollutants is ubiquitous, and it has been suggested that chronic, low-grade diet-induced acidosis may impair detoxification and increase risk of environmental illness over time (22). Again this idea is difficult to test, but the concept has a compelling scientific rationale (22).

Alkaline nutritional therapy

While nutritional supplements, especially alkaline salts of potassium, may be useful there are potential adverse effects in people with heart, lung or kidney disease and should consequently be used only under the guidance of a health professional (2). But for most people alkaline mineral combinations of potassium, calcium and magnesium as citrates or bicarbonates and perhaps green foods, vegetables juices or smoothies could be a simple and safe way to reduce acidosis for most people (see table 2).

Table 2: Examples of Alkalizing Dietary Supplement Studies

Nonetheless food is the clearly the best approach and improving the net alkaline potential of your diet is straightforward; increase fruit and vegetable intake. This simple strategy will displace acid forming foods and counterbalance their acidic effect. A reduction in salt will also reduce acidity, especially in people who are salt sensitive (25).

It is important to keep in mind that adequate protein intake is important for general health as well as facilitating acid excretion, so a very low-protein diet could in fact increase acidosis and have adverse health effects (2). Perhaps we should heed Sagen Ishizuka’s intuition and consider acid-alkaline nutrition as a natural balance of Yin and Yang, and not as the radical consumption of only alkaline food that is sometimes proposed.

A dietary pattern based on traditional foods that naturally change in acid-alkaline qualities from meal to meal and with shifts in seasonal food availability may well be the model (mostly) alkaline diet.

This article first featured in CAM Magazine, October 2014.

References:

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