There are many studies that examine between meal supplements as well as total liquid meals replacements if you are referring to products like Ensure or Sustacal. These liquid formulas are designed to provide 100% of the RDA in approximately 1800 calories and 5 to 8 cup (1200 to 1800 ml). I would suggest you check the Journal of the American Dietetic Association, which has an index in the December issue. Also, the Journal of Clinical Nutrition would be another good source. These should be available in the library of any university that has a nutrition science department. Have you done an online Medline search of the medical literature for liquid supplements?
These supplements are usually prescribed for persons who need to supplement their food intake with calories, protein, vitamins or minerals or who are unable to eat any solid food. The issue of the world’s increase in population or degradation of soils used to grow food is not going to be solved with liquid supplements as most are milk based. Cows need more acreage to graze and produce milk or meat than the equivalent caloric and protein from grains, fruits, and vegetables. Also, liquid supplements are more expensive than whole foods.
