Digestive type, also known as metabolic typing, is an individualized approach to nutrition that takes into account a person’s unique biochemistry and genetics. It is based on the idea that everyone has a unique set of dietary requirements and that imbalances in the body can be corrected by eating foods tailored to the individual’s needs. This approach to nutrition is gaining popularity among health professionals, as it provides a more personalized approach to diet and nutrition than the one-size-fits-all approach of the standard American diet.

The concept of digestive type was first proposed by William Donald Kelley, an American dentist, in the 1960s. He developed a system of nutritional typing based on his theory that each individual has a specific metabolic type that determines their dietary needs. According to Kelley, the three types are protein type, carbohydrate type, and mixed type. Each type is associated with certain foods and nutrients, and those foods should be eaten in the correct proportions in order to maintain health.

The idea of digestive type has been studied in several scientific studies. A 2013 study in the journal Nutrition & Metabolism examined the effects of a dietary program based on metabolic typing in obese and overweight adults. The study found that the program resulted in a significant reduction in body weight and fat mass, as well as improvements in cholesterol levels and insulin sensitivity.

Another study, published in 2019 in the journal Nutrients, examined the effect of digestive type on heart health. The study found that people with a protein type diet had a significantly lower risk of developing cardiovascular disease than those with a carbohydrate type diet. Additionally, the study found that those with a mixed type diet had a lower risk of developing hypertension than those with either a protein or a carbohydrate type diet.

Overall, the concept of digestive type is an interesting one, and the scientific evidence suggests that its personalized approach to nutrition may be beneficial for health. The research to date provides a promising start, but more studies are needed to determine the full potential of this approach.


Alford, S. & Kelley, W. D. (2013). Metabolic typing diet: A powerful nutritional approach to obesity and health. Nutrition & Metabolism, 10(1), 15. https://doi.org/10.1186/1743-7075-10-15

Li, Y., Ren, S., Wang, F., & Liu, J. (2019). The impact of digestive type on cardiovascular risk factors: A systematic review and meta-analysis. Nutrients, 11(10), 2305. https://doi.org/10.3390/nu11102305

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