One of the most important indicators of heart or cardiovascular disease is atherosclerosis—the hardening and thickening of the arteries. Atherosclerosis occurs as artery walls are damaged from oxidized low-density lipoproteins, initiating an inflammatory response.  Lipoproteins transport cholesterol and triglycerides through the bloodstream as either very-low density (VLDL), low-density (LDL), intermediate-density or high-density lipoproteins (HDL).

Cholesterol comes from our diet and from liver synthesis—which is sent with bile into the intestines. Here it is absorbed into the blood through the intestinal wall and transported via lipoproteins. Higher VLDL-c and LDL-c levels tend to oxidize more quickly, so these tend to cause more artery inflammation. HDL-cholesterol, on the other hand, does not oxidize as easily.

Probiotics will bind to and prevent LDL-cholesterol from being released back into the bloodstream. This effect reduces levels of cholesterol, and more importantly, levels of LDL-cholesterol in the blood. By reducing LDL-c and increasing HDL-c, less oxidation will take place and less artery damage will result.

Scientists from Denmark’s The Royal Veterinary and Agricultural University (Agerholm-Larsen et al. 2000) gave 70 overweight and obese adult volunteers 1) placebo pills; 2) a placebo yogurt; 3) a yogurt with two strains of Streptococcus thermophilus and two strains of Lactobacillus acidophilus; 4) a yogurt with two strains of Streptococcus thermophilus and one strain of Lactobacillus rhamnosus; or 5) a yogurt with one strain of Enterococcus faecium and two strains of Streptococcus thermophilus. After eight weeks, LDL-cholesterol decreased by 8.4% (0.26) while fibrinogen increased (0.74) in the Enterococcus faecium-Streptococcus thermophilus group (#4). Groups #3 and #4 showed significant decreases in blood pressure as well.

Twenty healthy men were given either milk fermented with Lactobacillus casei or a placebo for eight weeks in a double-blind, placebo-controlled study from Japan (Kawase et al. 2000). Blood samples were taken before, after 4 weeks and after 8 weeks. After 4 and 8 weeks, the high-density lipoprotein cholesterol levels (HDL-c) were significantly higher for the probiotic group while the placebo group showed no change. The probiotic group also had lower triglycerides levels after 4 weeks while the placebo group showed no change.

Scientists from the University of Kentucky (Anderson and Gilliland 1999) conducted two studies: One a single-blind study, and the other a double-blind, placebo-controlled, crossover study. Volunteers completed three and four week trials with either placebo or two different strains of L. acidophilus. The combined analysis of both probiotic studies showed a 2.9% reduction in serum cholesterol. The authors commented that this converts to a potential 6 to 10% lowering of coronary heart disease.

Researchers from the Tehran University of Medical Sciences (Ataie-Jafari et al. 2009) gave 14 healthy subjects with serum total cholesterol levels of 200 to 300 mg/dL 300 grams of ordinary yogurt or yogurt fermented with Lactobacillus acidophilus and Bifidobacterium lactis. After the six-week period, the probiotic yogurt group showed a significant decrease in total cholesterol levels compared to the ordinary yogurt group.

Forty-three volunteers were given either a placebo or Enterococcus faecium M-74 plus 50 micrograms of organically bound selenium in a double-blind, placebo-controlled study (Hlivak et al. 2005). After 56 weeks, total cholesterol among the probiotic group reduced from 229 to 201 mg/dL. LDL cholesterol fell from 149 to 119 mg/dL. No significant changes were seen in the placebo group. The researchers concluded that E. faecium reduced serum cholesterol by 12% during the test period.

Researchers from Germany’s Friedrich Schiller University (Kiessling et al. 2002) first gave 300 grams of control yogurt (with starter culture of Streptococcus thermophilus and Lactobacillus lactis) per day to 29 women for seven weeks. Then they had 18 women eat the same amount of yogurt enhanced with Lactobacillus acidophilus 145 and Bifidobacterium longum 913 per day while the others ate the control yogurt for the next seven weeks. During the third seven weeks, the two groups from the second period were reversed. After testing with all groups, the probiotic-enhanced groups had an average of 11.6 mg/dL increase in HDL cholesterol. Levels of LDL and total cholesterol were unchanged.

Scientists from The Netherlands’ Nutrition and Food Research Institute in Zeist (Schaafsma et al. 1998) gave 32 healthy men either a placebo milk or milk fermented with yogurt starter, Lactobacillus acidophilus and fructooligosaccharides. After two treatment periods of three weeks separated by a week off, the probiotic group had 4.4% less total cholesterol and 5.4% lower LDL-cholesterol.

Japanese researchers (Xiao et al. 2003) gave yogurt with a combination of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (SL), or the same combination with Bifidobacterium longum strain BL1 to 32 human subjects with total cholesterol from 220 to 280 mg/dL. After four weeks, the total cholesterol reduced by half in the B. longum group, while the cholesterol levels among the normal yogurt group remained nearly unchanged.

In research from Germany’s Friedrich Schiller University (Klein et al. 2008), 26 healthy volunteers took a yogurt supplement with probiotic strains L. acidophilus 74-2 and B. lactis 420 or a placebo for five weeks. After the five weeks, they were tested and crossed over. Final test results revealed that the probiotic group’s triglyceride levels decreased by 11.6%. Immune system granulocytes and monocytes with phagocytic activity significantly increased in the probiotic group as well.

References and more information are available from Probiotics – Protection Against Infection: Using Nature’s Tiny Warriors to Stem Infection and Fight Disease.