Studies indicate possible heart and digestive health benefits from colorful berries
by Craig Weatherby
Berries display a range of potential benefits in test tube, animal, and human studies.
And there is little doubt that most of the credit goes to the polyphenol antioxidants in these colorful fruits, some of which do double duty as red and blue pigments.
(To see our past articles about berrries, search our newsletter archive.)
Recent studies in animals and humans add to the positive indications concerning cardiovascular health and cancer.
Let’s take a fast look at the findings, which suggest that it’s smart to eat ample amounts of berries.
Berry-rich diets show cardiac benefits in clinical trial
Two weeks ago, Finnish researchers published the results of a study in which volunteers consumed a combination of bilberries, lingonberries, black currants and strawberries.
As they wrote, “Previous studies indicated that the consumption of polyphenol-rich foods (e.g., cocoa, tea, and red wine) may induce beneficial changes in pathways related to cardiovascular health. Whether the consumption of berries has similar effects is unknown” (Erlund I et al. 2008).
To find out, they recruited 72 middle-aged people (average age 58), including 46 women and 26 men. The participants were randomly assigned to eat either a moderate amount of berries or comparably sweet control foods for eight weeks.
On alternate days, the berry group consumed one of two regimens:
- 3.5 ounces of whole bilberries and 1.8 ounces of a lingonberry-rich nectar.
- 3.5 ounces of blackcurrant or strawberry purée and raspberry or chokeberry juice.
The control foods—chosen because they were low in polyphenol antioxidants—were sugar water, sweet rice porridge, marmalade, and sweet semolina porridge.
The results were encouraging, with the berry-eaters showing several benefits.
- Systolic blood pressure dropped by 7.3 mm of mercury in people with high blood pressure.
- Levels of HDL (“good”) cholesterol rose by 5.2 percent, compared with a negligible 0.6 percent increase in the control group. (Total cholesterol and triglyceride levels were not changed.)
- The “stickiness” (adherence and aggregation) of blood platelets fell by 11 percent, compared with a 1.4 percent rise in stickiness among the control group.
Their conclusion was straightforward: “The results indicate that regular consumption of berries may play a role in the prevention of cardiovascular disease” (Erlund I et al. 2008).
And they were clear about the reason for these beneficial effects: “According to the intake and bioavailability data obtained in this study, polyphenols and vitamin C are the most likely berry constituents to exert [beneficial] effects...” (Erlund I et al. 2008).
Raspberries reduce acid reflux and deadly associated risks
If you watch TV or read newspapers magazines, it’s pretty near impossible to miss the ads for drugs designed to treat the super-indigestion disorder called acid reflux.
Officially called gastro-esophageal reflux disease or GERD, it manifests as a burning sensation below and behind the lower part of the breastbone.
GERD can lead to Barrett's esophagus: a condition in which the esophagus—that is, the throat and its extension to the stomach—changes so that some of its lining is replaced by tissue like that found in the intestine.
Barrett's esophagus (BE) is not a major problem in itself, but about one in 200 patients with BE develop a deadly cancer called esophageal adenocarcinoma, which is frequently discovered too late for effective treatment.
Some 70,000 Americans develop esophageal cancer annually, and the survival rate after five years is only 15 percent.
So it comes as good news that black raspberries showed preventive promise in recent animal and human studies: results that suggest it may be wise for people with acid reflux or BE to relish lots of raspberries.
Animal experiment shows preventive potential
Last fall, a team from Ohio State University conducted an experiment in rats, with encouraging results. They fed freeze-dried back raspberries to rats that had also received a chemical called NMBA, which is known to cause esophageal cancer very quickly.
While the berry-rich diets did not reverse the growth of esophageal cancer once it appeared in rats, it prevented formation of tumors in the first place.
As the Ohio State team wrote, “…dietary FBR [freeze-dried raspberries] are highly effective in preventing the development of NMBA-induced esophageal tumors in rats when administered before and during NMBA treatment or shortly after NMBA treatment” (Stoner GD, Aziz RM 2007).
Human trial shows reduction in free radicals that promote esophageal cancer
Last December, an Ohio State University team led by assistant professor Laura Kresty, Ph.D., obtained positive results in a pilot human study that tested berries against the free radicals that promote esophageal cancer (Fromkes J et al. 2007).
They gave freeze-dried black raspberries to a group of 20 patients with Barrett's esophagus (BE) every day for 26 weeks.
The women received 32 grams (just over one ounce) of the raspberries a day, and the men consumed 45 grams (1.6 ounces) over the same six-month-plus period.
The researchers analyzed tissue, urine and blood samples before and after the study period.
- 37 percent showed increased expression of an enzyme called GSTpi, which detoxifies carcinogens and free radicals.
- 58 percent showed a significant reduction in 8-isoprostane. This metabolic product is an indicator of oxidative stress (from free radicals) and DNA damage, both of which have been linked to BE and esophageal cancer.
The Ohio State researchers were pleased: “These results are encouraging and support conducting a randomized placebo controlled trail in this patient cohort to more fully assess LBR as inhibitors of esophageal adenocarcinogenesis” (Fromkes J et al. 2007).
And as Dr. Kresty said in a press release, “Black raspberries have a good profile in terms of tolerability… we are simply administering a food in a non-traditional manner” (AACR 2007).
Sweet, tart berries in yogurt, on cereal, pureed on entrees, and added to blender drinks… now those are some tasty preventive prescriptions.
- American Association for Cancer Research (AACR). Diet and Cancer Prevention: New Evidence for the Protective Effects of Fruits and Veggies. December 6, 2007. Accessed online February 17, 2008 at http://www.aacr.org/home/about-us/news.aspx?d=945
- Carlton PS, Kresty LA, Siglin JC, Morse MA, Lu J, Morgan C, Stoner GD. Inhibition of N-nitrosomethylbenzylamine-induced tumorigenesis in the rat esophagus by dietary freeze-dried strawberries. Carcinogenesis. 2001 Mar;22(3):441-6. PMID: 11238184
- Chen T, Hwang H, Rose ME, Nines RG, Stoner GD. Chemopreventive properties of black raspberries in N-nitrosomethylbenzylamine-induced rat esophageal tumorigenesis: down-regulation of cyclooxygenase-2, inducible nitric oxide synthase, and c-Jun. Cancer Res. 2006 Mar 1;66(5):2853-9.
- Erlund I, Koli R, Alfthan G, Marniemi J, Puukka P, Mustonen P, Mattila P, Jula A. Favorable effects of berry consumption on platelet function, blood pressure, and HDL cholesterol. Am J Clin Nutr. 2008 Feb;87(2):323-31.
- Fromkes J, Frankel W, Stoner GD, Hammond C, Kresty LA. Dietary administration of black raspberries modulates markers of oxidative stress in patients with Barrett's esophagus. Poster Sesson B: Carcinogenesis – Animal Models of Carcinogenesis and Chemoprevention. Poster no. B34. American Association for Cancer Research Sixth Annual International Conference on Frontiers in Cancer Prevention, December 5-8, 2007, Philadelphia, Pennsylvania
- Stoner GD, Aziz RM. Prevention and therapy of squamous cell carcinoma of the rodent esophagus using freeze-dried black raspberries. Acta Pharmacol Sin. 2007 Sep;28(9):1422-8.
- Stoner GD, Chen T, Kresty LA, Aziz RM, Reinemann T, Nines R. Protection against esophageal cancer in rodents with lyophilized berries: potential mechanisms. Nutr Cancer. 2006;54(1):33-46.