When people say, "You must alkalinize your body." You can respond with, "What part of the body are you talking about?"
Actually a healthy body drastically ranges in pH depending on the organ system and its function. (They weren't told this at their MLM meeting where magic water cures every known disease.)
pH is a scale of acidity from 0 to 14 based on the concentration of protons (H+) in a solution.The lower the number the more acid and the higher the number the more alkaline. Different systems of the body operate optimally in different pH ranges. For example, when the stomach is functioning optimally the normal pH is around 1.2 (very acid!!). This is why drinking apple cider vinegar (which is acidic) actually improves digestion. The oral cavity is much more alkaline compared to the stomach.
The pH balance of your blood stays within a very narrow range. If it changed too much you would go into a coma and die. For this reason it is ridiculous to think that any change in your diet will significantly affect your blood pH. If this was the case, we would never have survived as a species (that first pizza would've killed us off for sure).
Btw, checking your urinary and oral pH has nothing to do with blood pH. These numbers can change per meal making the conclusions people draw from them sometimes silly.
There are a handful of buffer systems that constantly adjust the climate of the body. The kidneys, for example, have two very crucial roles in maintaining the pH balance: to reabsorb and regenerate bicarbonate from urine, and to excrete hydrogen ions and fixed acids (anions of acids) into urine.
Your body adjusts its pH so that you don't have to.
If you eat foods that damage your body, and subsequently damage your buffer systems, then you're in trouble. For example, eating a diet high in carbohydrates (especially processed) is associated with diabetes and related kidney dysfunction. If the kidneys are not functioning properly then the acid balance function will be compromised resulting in acidosis (bad). But this is not because the carbohydrate foods are directly changing your pH!
Notice on the chart that fruit is very alkaline but is actually not good for a diabetic because it's high in sugar. Also important to note that proponents of Alkaline Diets encourage the consumption of vegetables which are truly great for health (just not for the reasons they're promoting).
Many of the claims are bogus and founded on false notions. With that said, these people are often experiencing improvements in their health. This could be for many reasons. If they joined a belief system then it could be psychogenic. Positive beliefs are powerful. In practice I come across many bizarre and unfounded ideas but if it helps the patient emotionally, and is not harmful, then I leave it alone. Joining MLMs can be very motivating. A person might start taking better care of themselves, exercise more, eat better, and of course drink more water all of which will significantly improve health.
It is possible that introducing large amounts of alkaline water into the stomach (which is functionally acidic) creates a compensatory response of the stomach to produce more acid thus improving its function. Digestion would improve short term but because the stomach is stressed it will be followed by a worsening of digestive function over time.
This is major oversimplification. Cancer is an opportunist and takes root in a compromised system. There are many aspects of that system to consider with each person being unique. Anyone pointing to the one and only factor is likely selling something.
The pH of many foods completely changes after digestion as the components hit the blood stream making food pH charts less useful. I see great foods above and below the neutral line. I suggest eating a whole foods diet low in processed foods and to see a doctor trained in clinical nutrition if needed.