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Numerous studies have investigated the impact of an alkaline (low-acid, or "basic") diet, both on general health and as a treatment for certain conditions. Some benefits have been discovered, but the majority only applied to those suffering from specific conditions, and only when combined with other treatment methods. Benefits to healthy individuals are negligible in most cases, and those that are recorded often result from a combination of dietary changes, where alkalinity may play a secondary role to overall nutritional improvements. In other instances, excess alkalinity has resulted in detrimental effects. Unfortunately, some opportunistic authors have sensationalized these benefits for financial gain, and the resulting misinformation masks the proven benefits.
Scientists have been examining acid and alkaline forming foods since at least the 1930s. Modern studies about the effects of diet on pH (acidic-basic) balance gained ground in the 1980s when scientists worked to calculate acid/alkaline ash contents from diet, and validate it in predicting urine pH in the Journal of the American Dietetic Association.¹ Public interest in an alkaline-focused diet did not rise much, as data from Google Trends shows, until January 2013, when Victoria Beckham, a famous pop singer and fashion designer, posted a tweet promoting an alkaline cookbook, Honestly Healthy by Natasha Corrett and Vicki Edgson.
Since then, many trending lifestyle websites and blogs have been sharing information and claims about the benefits of an alkaline diet. For instance, Hello Magazine² published an article about the cookbook and its recipes, claiming that an alkaline diet "could be the solution to banishing your body's common complaints, even boosting your immune system, increasing energy and maintaining blood sugar levels." In addition, the Pacific Heart Lung & Blood Institute³ describes an alkaline diet as a "proven way to fight off cancer." Another article written by Dr. Axe⁴ alleges numerous benefits resulting from dietary alkalinity and claims that an alkaline diet promotes longevity, disease prevention, and even weight loss. These claims, while alluring to readers, are not backed up by scientific study.
When referring to an alkaline diet, it is important to understand what it is, how it works, and how it impacts the body. According to an article in the American Journal of Public Health⁵ by James A. Tobey, a lecturer at Harvard University School of Public Health, alkaline-forming foods are rich in calcium (Ca), magnesium (Mg), and potassium (K). Examples include fruits, vegetables, and to a lesser extent, dairy. The common misconception is that by controlling our acidity and alkalinity intake, we can manage the body's pH level. However, the National Center for Biotechnology Information⁶⁽²⁾ (NCBI) reveals that pH level is not constant throughout the body; the alkalinity (or acidity) of the human body varies greatly between different organs and tissues, with significant acidity present in the stomach, skin, and female reproductive systems. Reducing the acidity of these organs and tissues would compromise their intended functions, and make the body more susceptible to microbial overgrowth. The British Journal of Nutrition⁷ goes on to explain that food type does not trigger acidosis or alkalosis — a condition in which body fluid is excessively acidic or basic — since homeostatic processes will correct any imbalance that disrupts the internal acid-base equilibrium. While the journal acknowledges that urine acidity (pH level) varies depending on food consumption, it is a result of the homeostatic system, and does not reflect the changes in other measurements like extracellular potassium, sodium (Na), phosphate, or blood pH level, each of which are minimally affected by nutritional consumption unless extreme dosages are introduced.
It is vital to emphasize that no direct correlations have been discovered to show that an alkaline diet can mitigate bone loss, stave off disease, or prevent cancer. It is noted by NCBI⁶⁽³⁾ that no data has been found to support the use of an alkaline diet for bone health, or for any protective role of dietary acid in osteoporosis. However, they offer evidence to show that a sodium-rich diet can cause bone and muscle loss, but dietary potassium, which increases the K/Na ratio, can reduce the effect of excess sodium. An adequate vitamin D and protein supplement are important in improving bone density, but only when they are buffered by alkali-rich food components. The studies conclude that an alkaline diet is beneficial for bone health only when combined with adequate protein and vitamin D intake. In reference to disease prevention and the immune system, Hallelujah Diet⁸ claims that "Disease has a hard time surviving in an alkaline environment," but no studies have been found to support this claim. In general, different bacteria can survive in different pH ranges, and an alkaline diet does not substantially affect your body's internal pH level. Consequently, the consumption of alkali rich foods alone has not been demonstrated to be beneficial in combating or preventing disease. Similarly, there is no correlation between an alkaline diet and the prevention of cancer, although alkalinity can be beneficial for certain chemotherapy agents such as epirubicin, doxorubicin, and adriamycin (which require an alkaline media to be effective).⁶⁽⁷⁾ An article in the British Journal of Cancer⁹ about enhancing chemotherapy effect through the manipulation of pH level states that alkalinization increases the efficacy of doxorubicin by two to three times, and combination therapy with bicarbonate (an alkaline ion) significantly reduces tumor growth rate. This discovery is important because it increases the effect of chemotherapy without increasing the dosage, and therefore reduces morbidity caused by accelerated (increased) dosing.
An alkaline diet is found to be beneficial in the treatment of patients with specific conditions. For example, it is used to correct severe cases of metabolic acidosis, a cellular chemical imbalance when too much acid to accumulate in the body when homeostasis fails to correct the equilibrium. Bicarbonate supplements are used to protect muscles from sarcopenia (muscle loss) — a condition that is commonly associated with diabetic ketosis, chronic lung disease, and renal failure due to metabolic acidosis.4,6 Metabolic acidosis in children and postmenopausal women can result in low levels of growth hormone, but correctional treatment with bicarbonate and alkaline dietary supplements reduces the net diet acid load, and improves growth hormone levels significantly.5,6 NCBI also found that improving growth hormone levels correlates to an improvement in quality of life, body composition, memory, and reduces cardiovascular risk factors.⁶⁽⁵⁾ Furthermore, there are some evidences that an alkaline diet can help improve back pain: taking alkaline supplementation increase the intracellular magnesium level and ensure a proper activation of vitamin D (as aforementioned, alkali-rich foods buffer the absorption of proteins and vitamin D).6(6) A case-study in the Journal of the American Board of Family Medicine10 about chronic back pain shows that sufficient repletion of vitamin D to normal levels improves back pain and potentially results in complete recovery. Studies on the effect of an alkaline diet on healthy individuals are limited, but they note that there is no direct apparent harm associated with an alkaline diet (which consists of many fruits, nuts and vegetables, and limited quantity of meat and dairy) since it is a traditional and healthy way to eat.11