Blood pH and diet

Blood pH is relatively constant at around 7.4 because the body will strip calcium from bones, if necessary, to buffer it in the absence of alkaline-forming food components. That is not homeostasis. But blood pH does vary (typically within a range of 6.8 to 7.8, with potentially lethal effects beyond that range) and affects urine pH, which we can easily measure. 

Dietary compounds formed in the body affect blood pH; not the contrasting pH levels in the digestive tract (acid in the stomach and neutral in the small intestine) or the apparent acidity of foods, but what happens after digestion. The minerals or weak acids (citrates, et al) in alkaline-forming foods are used to make alkaline compounds in the body, which won't happen efficiently with a processed food or a non-plant-derived diet. Scientists have measured this effect and doctors have utilized it in practice, so it's not theoretical or based on pH limited to areas of the digestive tract. https://www.drrusselljaffe.com/7-principles-eating-alkaline-way/ 

"An advanced understanding of acid–base physiology is as central to the practice of critical care medicine, as are an understanding of cardiac and pulmonary physiology. Intensivists spend much of their time managing problems related to fluids, electrolytes, and blood pH. Recent advances in the understanding of acid–base physiology have occurred as the result of the application of basic physical-chemical principles of aqueous solutions to blood plasma. This analysis has revealed three independent variables that regulate pH in blood plasma. These variables are carbon dioxide, relative electrolyte concentrations, and total weak acid concentrations. All changes in blood pH, in health and in disease, occur through changes in these three variables. Clinical implications for these findings are also discussed." https://www.ncbi.nlm.nih.gov/pmc/articles/PMC137247/ 

Foods and Supplements for a Ketogenic Diet

Ketosis occurs when the body is largely starved of carbohydrates but has an alternate energy source. Ketogenic products encourage the burning of fat in place of sugar/carbohydrates as a caloric source. The key is to avoid rises in blood sugar and insulin, while providing alternate fuels.

There are numerous keto-friendly products; these are considered to be those that contain fewer than 10 calories per serving of net carbohydrates (minus fiber). Fiber doesn’t raise blood sugar and insulin response, so is neutral and not counted when looking at labels. Most dietary supplements fall into the category of being ketogenic neutral; that is, they neither contain significant carbohydrate sources nor directly contribute ketogenic stimulating substances like fat. The main ketogenic products are fats: MCT and coconut oils (both contain MCTs) are the most important ones. Some take beta-hydroxybutyric acid, a ketone, directly.

Ketogenic diets tend to decrease electrolytes and increase the need for water. This increases the need for magnesium, potassium, and even sodium. If blood sugar drops too low, the kidneys can create blood sugar by converting the proteins (i.e. the amino acid glutamine) into glucose (gluconeogenesis), so high protein diets are also discouraged. This leaves non-starchy vegetables and fats as the most desirable parts of the diet, along with some protein and fiber. Nuts and seeds are often okay, but some are more starchy; check the labels. Dairy is largely out due to its lactose content, but non-dairy foods and beverages may be okay if also low carb. Fish oil supplements are desirable. Green foods are important; supplements like chlorella or spirulina can be very useful, as can wheatgrass or barley grass.

Other supplements used on a ketogenic regime include green tea and EGCg capsules, L-glutamine if exercising (it can convert to sugar, so use sparingly), 7-keto DHEA, collagen or gelatin or bone broth. Anti-inflammatory substances may also be helpful: turmeric and curcumin, ginger, etc.

Unless eating natural or fortified sources of vitamin D, or getting adequate sun exposure, supplementation of this vitamin is recommended. A multiple vitamin is the best source, assuming it has enough for your needs,  as it also supplies other nutrients needed for metabolism of fats and energy production. Calcium supplementation may be needed unless consuming lots of green vegetables. Look for digestive enzymes that supply lipase if consuming lots of fat (not needed for MCT oil). Supplements containing ox bile (also in some digestive enzyme formulas) may be needed if inadequate gall bladder function is suspected or known. Don’t forget the electrolytes!