Insulin-like growth factor-I may boost death risk in older men

A new study in the Journal of Clinical Endocrinology & Metabolism has found older community dwelling men with cancer who displayed high levels of insulin-like growth factor-I were more likely to die than those who had lower levels. 

The prospective, population-based study led by Jacqueline M. Major and colleagues from the University of California San Diego School of Medicine involved 633 men aged 50 whose blood samples were collected for measurement of IGF-I when they attended a clinic visit between 1988 and 1991. 

During the 18-year follow-up, 368 deaths were identified; 20% of those deaths were due to  cancer. 

The researchers found a significant association between IGF-I and all-cancer mortality. 

Those with 120 ng/mL of IGF-I levels were 61 to 161 percent more likely to die, compared to those with lower levels. And those with above 100 ng/mL, the risk of fatal cancer was 82 percent higher compared to those with lower levels. 

The researchers concluded "Higher serum IGF-I in older men is associated with increased risk of cancer death, independent of age, adiposity, lifestyle, and cancer history. These results suggest caution in the use of IGF-I-enhancing therapies to slow the adverse effects of aging." 

IGF-I is a protein that is encoded by the IGF1 gene in humans.  It plays an important role in childhood growth and continues to have anabolic effects in adults, according to Wikipedia. 

According to the current study, IGF-I has been linked with incidence of cancer. 

So what foods may boost the level of IGF-I in a person's blood? 

A study published  in the European Journal of Clinical Nutrition suggest eating meat, cheese, milk and some types of minerals may boost the production of IGF-1. 

The study of 2,109 women led by Norat T. and colleagues from International Agency for Research on Cancer in Lyon, France - a health agency under the World Health Organization - found IGF was positively related to intake of protein, milk, calcium, magnesium, phosphorus, potassium, vitamin B6, vitamin B2.   

In contrast, eating vegetables and beta-carotene was inversely associated with IGF-I levels, the study also found. 

The researchers in the current study found energy, fat or carbohydrate intake was not associated with IGF-i production. 

It is not clear in terms of what type of protein boosts IGF-I and what type of carbohydrate was not related with IGF-I levels. 

A recent study led by Japanese researchers found eating tofu may also reduce IGF levels. 

Studies have found carbohydrates like glucose and table sugar that bolster the glycemic index of a diet tend to boost the production of IGF-I.

David Liu and editing by Rachel Stockton