Sugars and starches lower our immunity to infectious diseases

Part 2: Leukocytic Index Test results

That sugars and starches might affect the ability of immune cells to mop up bacteria and viruses was tested in 1973. After an overnight fast and after their leucocytes had been tested for phagocytosis activity and their leukocytic index (LI) had been recorded, subjects were fed 100 grams of a specific carbohydrate (a sugar or starch) and the effect on immune function was measured.

The table below shows that all forms of carbohydrate — starch as well as sugars — reduced the neutrophils' effectiveness at destroying bacteria and other micro-organisms. (1)

Note that the worst 'sugar' was fructose, which reduced the ability of white blood cells to mop up bacteria by 45%. Fructose is the sugar found in fruit. Orange juice, which produced a decline in immune function of 42%, wasn't far behind. This means that, if you religiously eat fruit at all meals — and how else are you going to fit all those 'portions' in? — you could lose a lot of your body's natural immunity to infection for most of the day.

Fasting level of LI Lowest point of LI Decline
Time before returning to normal
Glucose 16.2 9.6 40.5 More than 5 hours
Fructose 15.5 8.5 45.1 More than 5 hours
Sucrose 15.2 8.6 44.0 More than 5 hours
Honey 15.9 9.7 39.0 More than 5 hours
Orange juice 16.6 9.6 42.1 More than 5 hours
Starch 15.7 13.6 13.4 More than 5 hours

This study was confirmed in 1976 by Ringsdorf, et al. (2) They tested the effect of sugar (sucrose) by giving their subjects 24 ounces of sugar sweetened Cola. In this test the leucocytic index of all their subjects was reduced by 50%. In other words, the ability of their disease-fighting blood cells was halved.

One has to wonder in what way eating a lot of fruit is 'healthy'.


1. Sanchez A, et al. Role of sugars in human neutrophilic phagocytosis. Am J Clin Nutr 1973; 26: 1180-84
2. Ringsdorf WM jr, Cheraskin E and Ramsey RR jr. Sucrose, Neutrophilic Phagocytosis, and Resistance to Disease. Dent Surv 1976; 52 (12): 46-48

Part 1: Introduction | Part 2: Leukocytic Index | Part 3: consequences

Bookmark and Share
Last updated: December 9, 2011