Low levels of protein tied to muscle decline

Older adults with relatively low levels of a particular blood protein may have a significant decline in muscle strength over time. The protein, called albumin, is known to fall to abnormal levels in certain diseases, including kidney and liver disease. In addition, high levels of other inflammatory proteins in the blood can lower a person's albumin levels; chronic inflammation in the body is believed to contribute to a number of medical conditions, such as heart disease. It's uncertain whether increasing an older person's albumin levels would improve his or her strength. Researchers form the University Medical Center in Amsterdam, Netherlands, studied more than 1,000 adults ages 65 to 88 whose changes in albumin levels and muscle strength were followed for at least 3 years. They measured participants' blood levels of albumin and particular proteins involved in inflammation, and gathered information on their lifestyles and any existing medical conditions. Grip strength tests were used to gauge their muscle strength. The researchers found that nearly all of the study participants - 99 percent - had normal albumin levels at the study's outset. Yet those with the lowest levels relative to their peers had poorer muscle strength. These men and women tended to lose more muscle strength over the next 3 to 6 years. This relationship held true, though it weakened somewhat, when the researchers factored in participants' health conditions, levels of inflammatory proteins and lifestyle habits like smoking and exercise. The subjects also showed a greater loss in muscle strength over time. A missing element from the data was detailed information on diet. Poor nutrition, they note, through effects on protein synthesis in the body, could spur a decline in muscle strength. Since low protein intake and general malnutrition can trigger a drop in albumin, future studies should look at the effects of special diet regimens on older adults' albumin levels and muscular strength. The researchers add that since this is the first study to link blood albumin levels to age-related muscle decline, more studies are needed to confirm the relationship and to identify the underlying cause.