ARE YOU AS OLD AS WHAT YOU EAT

Researchers from UCL (University College London) have demonstrated how an interplay between nutrition, metabolism and immunity is involved in the process of aging

The two new studies, supported by the Biotechnology and Biological Sciences Research Council (BBSRC), could help to enhance our immunity to disease through dietary intervention and help make existing immune system therapies more effective.

As we age our immune systems decline. Older people suffer from increased incidence and severity of both infections and cancer. In addition, vaccination becomes less efficient with age.

In previous BBSRC funded work, Professor Arne Akbar's group at UCL showed that aging in immune system cells known as 'T lymphocytes' was controlled by a molecule called 'p38 MAPK' that acts as a brake to prevent certain cellular functions.

They found that this braking action could be reversed by using a p38 MAPK inhibitor, suggesting the possibility of rejuvenating old T cells using drug treatment.

In a new study published in Nature Immunology the group shows that p38 MAPK is activated by low nutrient levels, coupled with signals associated with age, or senescence, within the cell.

It has been suspected for a long time that nutrition, metabolism and immunity are linked and this paper provides a prototype mechanism of how nutrient and senescence signals converge to regulate the function of T lymphocytes.

The study also suggests that the function of old T lymphocytes could be reconstituted by blocking one of several molecules involved in the process. The research was conducted at UCL alongside colleagues from Complejo Hospitalario de Navarra, Pamplona, Spain.

The second paper, published in The Journal of Clinical Investigation, showed that blocking p38 MAPK boosted the fitness of cells that had shown signs of aging; improving the function of mitochondria (the cellular batteries) and enhancing their ability to divide.

Extra energy for the cell to divide was generated by the recycling of intracellular molecules, a process known as autophagy. This highlights the existence of a common signaling pathway in old/senescent T lymphocytes that controls their immune function as well as metabolism, further underscoring the intimate association between aging and metabolism of T lymphocytes.

This study was conducted by researchers from UCL, Cancer Research UK, University of Oxford and University of Tor Vergata, Rome, Italy.

Professor Arne Akbar said: "Our life expectancy at birth is now twice as long as it was 150 years ago and our lifespans are on the increase. Healthcare costs associated with aging are immense and there will be an increasing number of older people in our population who will have a lower quality of life due in part to immune decline. It is therefore essential to understand reasons why immunity decreases and whether it is possible to counteract some of these changes.

"An important question is whether this knowledge can be used to enhance immunity during aging. Many drug companies have already developed p38 inhibitors in attempts to treat inflammatory diseases. One new possibility for their use is that these compounds could be used to enhance immunity in older subjects. Another possibility is that dietary instead of drug intervention could be used to enhance immunity since metabolism and senescence are two sides of the same coin."

EAT PEANUTS FOR A LONGER LIFE

If you're looking for a simple way to lower your risk of dying from a heart attack, consider going nuts.

Researchers at Vanderbilt University and the Shanghai Cancer Institute examined the association of peanut and nut consumption with mortality among low-income and racially diverse populations and found that intake of peanuts was associated with fewer deaths, especially from heart disease.

The study was published March 2 in JAMA Internal Medicine. The first author of the paper is Hung Luu, Ph.D., a post-doctoral fellow in the Division of Epidemiology, Vanderbilt University Medical Center. Senior author is Xiao-Ou Shu, M.D., Ph.D., associate director for Global Health at the Vanderbilt-Ingram Cancer Center (VICC) and professor of Medicine in the Department of Epidemiology.

"Nuts are rich in nutrients, such as unsaturated fatty acids, fiber, vitamins, phenolic antioxidants, arginine and other phytochemicals. All of them are known to be beneficial to cardiovascular health, probably through their anti-oxidative, anti-inflammatory and endothelial function maintenance properties," Shu said.

While research has previously linked nut consumption with lower mortality, those studies focused mainly on higher-income, white populations. This study was the first to discover that all races -- blacks, whites and Asians alike -- could potentially increase heart health by eating nuts and peanuts.

"In our study, we found that peanut consumption was associated with reduced total mortality and cardiovascular disease mortality in a predominantly low-income black and white population in the U.S., and among Chinese men and women living in Shanghai," Shu said.

This study was based on three large ongoing cohort studies. Participants included more than 70,000 Americans of African and European descent from the Southern Community Cohort Study (SCCS), who were mostly low-income, and more than 130,000 Chinese from the Shanghai Women's Health Study (SWHS) and the Shanghai Men's Health Study (SMHS).

Information on nut consumption was collected by structured questionnaires at the baseline survey. For participants in the SCCS, deaths were determined by linking with the National Death Index and Social Security Administration mortality files, and for participants in the SWHS/SMHS, by linking with the Shanghai Vital Statistics Registry and by conducting home visits. In total, more than 14,000 deaths were identified, with a median follow-up of 5.4 years in the SCCS, 6.5 years in the SMHS, and 12.2 years in the SWHS.

Peanut consumption was associated with decreased total mortality, particularly cardiovascular mortality (i.e., 17-21 percent reduction in total mortality, and 23-38 percent reduction in cardiovascular mortality for the highest quartile intake group compared to the lowest quartile group) across all three racial/ethnic groups, among both men and women, and among individuals from low-SES groups.

Because peanuts are much less expensive than tree nuts, as well as more widely available to people of all races and all socioeconomic backgrounds, increasing peanut consumption may provide a potentially cost-efficient approach to improving cardiovascular health, Shu said.

"The data arise from observational epidemiologic studies, and not randomized clinical trials, and thus we cannot be sure that peanuts per se were responsible for the reduced mortality observed," said William Blot, Ph.D., associate director for Cancer Prevention, Control and Population-based Research at VICC and a co-author of the study.

He did note that "the findings from this new study, however, reinforce earlier research suggesting health benefits from eating nuts, and thus are quite encouraging."

The American Heart Association recommends eating four servings of unsalted, unoiled nuts a week. However, nutrient-rich nuts are also high in calories, so don't eat too many if you're watching your weight. A serving size is a small handful or 1.5 ounces of whole nuts or 2 tablespoons of nut butter.