A protein called membrane type 1 matrix metalloproteinase interferes with the body's ability to clear LDL ("bad") cholesterol, increasing the risk of heart disease.

Increases in the stress hormone cortisol causes hair follicle stem cells to remain in an extending "resting phase" without being able to regenerate the hair follicle, leading to hair loss.

Supplemental selenium protects against obesity in mice and extends lifespan in yeast by 62% by mimicking methionine restriction, which decreases the hormone IGF-1.

The benefits of fish oil depend on your genotype — certain people will see reductions in triglycerides (blood fat), while others increase triglycerides, based on variants of the gene GJB2.