Isolated protein, especially soy protein powder, is popularly blended into shakes and smoothies, but is this a healthful way to build muscle?
Protein intake, especially animal protein, is known to be the major dietary determinant of circulating IGF-1 levels. When we consume animal protein, the body increases its production of a hormone called IGF-1 (insulin-like growth factor 1). IGF-1 is one of the body’s important growth promoters during childhood, but later in life IGF-1 promotes the aging process.
IGF-1 has been shown to promote the growth, proliferation and spread of cancer cells, and elevated IGF-1 levels are linked to increased risk of several cancers.3-7 Our society’s obsession with over-consuming protein is a contributing factor to our epidemic of cancer. In addition to the issue of IGF-1 and cancer, excess protein may negatively affect calcium stores, kidney function and bone health, and promote cardiovascular events.8-10
The amino acid profile of animal protein sparks IGF-1 production.11 However, of all plant proteins, the essential amino acid profile of soy is said to be the most “complete,” meaning the closest to animal protein (other plant proteins contain more than adequate amounts of essential amino acids for human nutrition12. Therefore, unnecessarily high intakes of animal protein or soy protein could be harmful.
The soy products that are problematic are those that contain unnaturally concentrated soy protein, such as protein powders and meat substitutes; highly processed foods that retain little or none of the beneficial nutrients contained in whole soybeans. It is important to have a variety of beans in the diet, not just soybeans. Furthermore, soybeans should be eaten in their minimally processed forms: edamame, tempeh, tofu and unsweetened soymilk.
IGF-1 is very important for growth and maintenance of muscle tissue.13 However, muscle growth is not dependent on only the amount of IGF-1 circulating in the blood; muscle tissue produces its own IGF-1 in response to strength training to fuel muscle growth.14 So a combination of strength training and a Nutritarian diet will result in lower, cancer-preventive levels of IGF-1 levels circulating in the blood, while still allowing for local production of IGF-1 for muscle building.
Instead of micronutrient-poor protein powders, whole food sources of protein are the best choice. For blending into shakes and smoothies, I recommend high-protein plant foods such as sunflower seeds, hemp seeds and Mediterranean pine nuts.
These same foods can be incorporated into post-workout meals, along with generous amounts of green vegetables, beans and intact whole grains (such as oats, quinoa and wild rice) that are rich in micronutrients as well as protein. For those that insist on using isolated protein powders, hemp, rice and pea proteins are better choices than soy protein, since their amino acid profiles are not as close to that of animal protein.
Most important to note is that it is exercise and not food that stimulates muscle growth. Completing a workout triggers muscle building; dietary protein provides the raw materials that muscles need in order to grow.
Following a Nutritarian diet, which includes many protein-rich whole plant foods, allows for the easy consumption of adequate protein for muscle growth by increasing your total caloric intake based on your level of hunger.
Excess protein calories are not stored as protein (they are stored as fat) so it is important to provide the body with raw materials for muscle growth following a workout, as the muscles begin their recovery period. Naturally, we become hungry within an hour or two of a workout, and having a protein-containing meal closely following exercise is advantageous for recovery and muscle mass.1-2 Taking care to include protein-rich plant foods, like green vegetables, beans and seeds will provide sufficient raw material for muscle growth.