Lima Beans

Lima beans (Phaseolus lunatus) are thought to have evolved into a distinct species about a million years ago in the Andes.¹  They then went on to adapt slightly differently to the environment, for example elevation, in three different areas.¹  Lima beans are thought to have been domesticated from this wild species independently by three different cultures of people; one in Mexico, one in Central America, and one in South America.²  Archaeologic evidence suggests that the ancient Mayans prepared lima beans by boiling them.³

 

Lima beans are higher in available iron than other legumes, while like other legumes, they are considered to have a low glycemic index, due to their dietary fiber content.⁴ 

 

Seidu et al⁵ analyzed the nutritient content of lima beans and found that they have a lot of potassium, sodium, phosphorus, calcium, and magnesium, but were not the best source of manganese, zinc, or copper.  They note that like other legumes, lima beans are high in lysine but not a good source of methionine or cysteine.  Of the other amino acids, they found tryptophan to be slightly low. 

 

Jayalaxmi et al⁶ soaked lima beans for 24 hours and then allowed them to grow for another 48 hours, one way that they are commonly prepared, and found that this actually increases their protein content, because they are alive and make new proteins as they start growing; at the same time the fat decreases, since the energy is needed for this metabolic process.  They also determined that most of the fiber is contained in the seed coat, and would be lost in any processing method where you don’t end up eating the seed coat.

 

Brand et al⁷ tested a traditional lima bean recipe from the Pima Indians of Arizona, which involves simply soaking the lima beans overnight, and then boiling them with garlic and onions, and found that it had a low glycemic index.  They hypothesize that the reason that people whose ancestors lived in desert regions, like the Pima, have higher rates of diabetes, is that they evolved eating the low glycemic plants that live in the desert.  They go on to propose that the reason these plant foods have a low glycemic index is that they evolved to hold on to moisture since they live in the desert, and the compounds that allow them to do that may also result in their starches taking longer for us to digest. 

 

 

References

 

1. Serrano-Serrano ML, Hernández-Torres J, Castillo-Villamizar G, Debouck DG, Chacón Sánchez MI. Gene pools in wild Lima bean (Phaseolus lunatus L.) from the Americas: Evidences for an Andean origin and past migrations. Molecular Phylogenetics & Evolution. 2010;54(1):76-87. 
2. Andueza-Noh RH, Serrano-Serrano ML, Chacón Sánchez MI, et al. Multiple domestications of the Mesoamerican gene pool of lima bean (Phaseolus lunatus L.): evidence from chloroplast DNA sequences. Genetic Resources and Crop Evolution: An International Journal. 2013;60(3):1069-1086.