New Data on the Benefits of Prunes

This is an update of a column I wrote in 2015, with some new data on the osteoporosis benefits of prunes. Prunes are now called dried plums by some nutritionists and prune makers, because of their negative image as a medicinal food for the elderly.  Don’t be put off – read on!

Osteoporosis – Studies form Florida State University, published in the British Journal of Nutrition, showed that in rats subjected to treatments that produced osteoporosis, prunes in the diet were able to reverse bone loss.  In a human study, a group of post-menopausal women was given 100 grams of prunes per day (about 10 prunes) and a comparison group was told to consume 100 grams of dried apples.  After 12 months, the group eating the prunes had significantly higher bone mineral density in the ulna (an arm bone) and spine.  Authors of the study said that prunes are able to suppress bone breakdown, which tends to exceed new bone growth as people age.  This effect may be due to good levels of the mineral boron in prunes.  Other foods high in boron are plums, grapes, avocados, almonds and peanuts.  

A recent study from the Texas A&M Research center showed that prunes protect against the bone loss caused by ionizing radiation.  UC Irvine and UC San Francisco also participated in this research. The study, done in mice, showed that consuming prunes can protect from ionizing radiation that increases oxidative damage in skeletal tissues and results in an imbalance in bone remodeling. "Bone loss caused by ionizing radiation is a potential health concern for those in occupations or in situations that expose them to radiation," the study said. "This is relevant to not only astronauts in space, but also cancer patients, those undergoing radiotherapy, radiation workers and victims of nuclear accidents."

The team investigated interventions they thought might prevent bone damage and oxidative stress-related factors leading to cancellous bone loss, also known as "spongy bone," from exposure to both low linear energy transfer and high linear energy transfer radiation. They evaluated different interventions with antioxidant or anti-inflammatory properties, including an antioxidant cocktail, dihydrolipoic acid, ibuprofen and prunes, to determine their ability to prevent bone loss and to blunt the expression of genes in marrow cells that lead to the breakdown of bone. They found that prunes "contain biologically active components that may provide effective interventions for loss of structural integrity caused by radiotherapy or unavoidable exposure to space radiation incurred over long-duration spaceflight.” They noted that prunes contain various bioactive compounds, including polyphenols that are known for their high antioxidant and anti-inflammatory properties.

Laxative Effect – Prunes are well known for their ability to help with constipation.  They are a safe laxative for most people. This is due to their fiber and high sorbitol content, which retains fluid in the intestines.  Sorbitol is a natural sugar found in many fruits.  It is metabolized relatively slowly, so that prunes do not cause a rapid rise in blood sugar.  Many people with diabetes can eat them in moderation (but check with your health care provider). 

Colon Cancer – Research from Texas A&M University and the University of North Carolina has shown that prunes can positively affect gut bacteria (the microbiome) and help to reduce the risk of colon cancer. There are trillions of bacteria in the intestinal tract – more than 400 individual species have been identified.  Disruptions to the microbiome are involved in intestinal inflammation, which can promote the development of colon cancer. Prunes contain antioxidant compounds that can neutralize free radicals that damage DNA.  In a rat study on colon cancer antecedents, rats fed with prunes (and their regular chow) showed significantly reduced numbers of precancerous changes in the intestinal walls compared to a control group.

Weight Loss – Research by the University of Liverpool found that eating prunes as part of a weight loss diet helped in weight control.  100 overweight or obese men and women were tested for 12 weeks.  Half the subjects were given about 14 prunes per day along with their diet, and the other half got advice on healthy snacks.  The group that ate prunes lost 4.4 pounds and an inch from their waist.  The control group lost 3.5 pounds and .7 inches from the waist.  Also, the group eating prunes experienced greater feelings of fullness during the weight loss diet.  The diets were matched for calories.

Some people don’t like the taste of prunes, and may need to disguise them in shakes and stir-fries. If you have colon cancer in your family; if your diet is high in red or processed meat; if you have osteoporosis in your family, if you have low bone density yourself, or if you are a budding astronaut, you may want to give prunes a chance. 

           Sadja Greenwood, MD  Back issues at

           sadjascolumns.blogspot.com

       

The Common Cold – Zinc Lozenges, Vitamins C & D and a Probiotic may Help

Zinc Acetate Lozenges

 A recent analysis of randomized, placebo controlled trials of zinc lozenges, recently published in the British Journal of Clinical Pharmacology, showed that zinc acetate lozenges may reduce the duration of the common cold by nearly 3 days. The common cold is an infection caused by many different viruses. 

 The effect of zinc lozenges was not changed by allergy status, smoking, symptom severity, age, sex or ethnic group.  High dose zinc acetate lozenges shortened the duration of common cold symptoms of nasal discharge by 34% nasal congestion by 37%, scratchy throat by 33% and cough by 46%.   Zinc lozenges also shortened the duration of muscle aching by 54%.  However, there was no evidence of zinc effect on headache or fever.   Because high doses of zinc can cause side effects such as nausea, dosage of lozenges should not exceed 100 mg per day.  Most zinc acetate lozenges have 18.75 mg of zinc; taking two daily is helpful for most people.  Simply taking supplemental zinc in pill form may not have the same effects, because it is the zinc dissolved in saliva that is believed to be effective. 

 Vitamin C 

According to an updated review of vitamin C and the common cold, vitamin C halved the incidence of contracting the common cold among people undergoing physical stress, such as marathon runners, or people working in the cold.  Vitamin C may also reduce bronchoconstriction  (asthma-like symptoms) caused by exercise. Some, but not all studies, indicate that taking vitamin C shortens the duration of a cold.

Vitamin D

A recent report from the University of Colorado School of Medicine looked at the use of vitamin D among older, long-term care residents of nursing homes.  There was a 40 percent reduction in acute respiratory illness among those who were given 100,000 IU of vitamin D per month (averaging 3,300-4,300IU daily) compared to those receiving 12,000 IU per month (averaging 400-1000 units daily).  However, there were more falls, although not more fractures, in patients receiving the higher doses.  Further study will look at giving patients a daily dose of vitamin D rather than very high dosages monthly.  Numerous other studies of vitamin D have shown that supplements of D have lowered the incidence of respiratory infections in children and adults.  Most studies have shown that a blood level of at least 30 ng/ml of vitamin D is desirable.  Check with your primary care provider for a test of your vitamin D blood level.  In the meantime, taking a vitamin D supplement of 1000 IU is probably safe and desirable for most people, especially in the winter months when sun exposure is minimal at our latitude.  Have some zinc acetate lozenges on hand.  Keep up your vitamin C intake with citrus fruits and other raw fruits and vegetables, or take a supplement.

Probiotic Supplement

Consider taking a probiotic supplement as well – a study from the University of Medicine and Dentistry in New Jersey showed that students taking a probiotic supplement had a shorter duration of colds and symptoms that were 34% less severe.  Include fermented foods such as yogurt in your daily diet as well.

Finally – if you haven’t had a flu shot this year – it’s still not too late.  Go for it!

Sadja Greenwood, MD, MPH  back issues on this blog