Constipation is a pretty clear sign of a shortage of whole (un or minimally processed) plant foods. Your gut should need no lubrication...a gut which has a healthy microbiome, grown to take advantage of plentiful soluble and non-soluble fiber resources moves digested food right along. Web Md. lists as the worst foods for constipation; dairy, fast foods, fried foods, eggs, tender meat, bakery products like cake and cupcakes, white bread, and alcohol.

Personally, i think that smoothies are also suspect. Our digestive tracks are long adapted to thorough chewing, which mixes in important digestive enzymes, as the start of the digestive process. We are not adapted to swallow whole and then digest food pre-chewed by machines;)