Most bacteria thrive in slightly acid conditions. Slightly alkaline blood keeps bacteria from multiplying because it absorbs oxygen better. Oxygen hastens the breakdown of pathogenic bacteria, since most harmful bacteria are anaerobic (cannot tolerate oxygen.
The aerobic cycle is one of oxidation/reduction based on available oxygen in the bloodstream. When blood becomes acidic, less oxygen is absorbed. Cells need oxygen to metabolize food and convert it to energy. If cells do not get enough oxygen, they can no longer function normally – aerobically.
Alkaline blood absorbs oxygen in sufficient quantities to oxidize food, convert it to energy and neutralize acidic waste products, a normal aspect of food metabolism. Body cells switch to anaerobic energy production when they can no longer derive enough oxygen from blood cells.