Is it the milk? Lactose intolerants at lower risk of certain cancers
People with lactose intolerance are
at lower risk of suffering from lung, breast and ovarian cancers, according to
a new study by researchers at Lund University and Region Skåne in Sweden.
"We found that people with lactose intolerance, who typically consume low amounts of milk and other dairy products, have a reduced risk of lung, breast and ovarian cancers", says Jianguang Ji, Associate Professor at Lund University and researcher at the Center for Primary Care Research in Malmö.
"The risk of cancer was not reduced in relatives of people with lactose intolerance, which indicates that protection against these cancers is related to diet. However, it would be wrong to conclude that milk is a risk factor for these cancers", emphasises Jianguang Ji.
There are large differences in the incidence of breast and ovarian cancers between different countries. Their incidence is highest in North America, Western Europe and the Nordic countries, and lowest in East Asia and Central African countries. Studies of immigrants and twins suggest this worldwide variation is more down to environmental factors than to genetic or ethnic factors.
Lifestyle factors such as high consumption of milk and other dairy products have been suspected to contribute to the high incidence of breast and ovarian cancers in North America and Western Europe. However, previous studies are inconclusive. One recent review by the World Cancer Research Fund and the American Institute of Cancer Research found a lack of evidence linking consumption of dairy products to breast cancer risk.
"In order to investigate this unanswered question we adopted a novel approach", says Jianguang Ji. "We investigated whether low consumption of milk and other dairy products protects lactose-intolerant people against breast and ovarian cancers. Since epidemiological and animal studies show that milk consumption and lung cancer risk are both associated with the protein IGF-1 (insulin like growth factor 1), we also investigated lung cancer."
"Using nationwide data from two Swedish registers (the Inpatient Register and the Outpatient Register) we identified 22,788 individuals with lactose intolerance and examined their risk of suffering from lung, breast and ovarian cancers. The risks of lung cancer (standardised incidence ratio [SIR] = 0.55), breast cancer (SIR = 0.79) and ovarian cancer (SIR = 0.55) were significantly lower in people with lactose intolerance compared to people without lactose intolerance, irrespective of country of birth and gender", explains Jianguang Ji. "By contrast, the risks in their siblings and parents were the same as in the general population. This suggests that the lower cancer risk in people with lactose intolerance may be due to their diet."
Factors such as lower calorie intake of because of low milk consumption and protective factors in plant-based milk drinks may contribute to the observed negative association between lactose intolerance and the studied cancers.
"We must interpret these results with caution because the association we found is insufficient to conclude a causative effect", emphasises Jianguang Ji. "Further studies are needed to identify factors that explain the study's results."
Cancer-protective properties of milk
Milk consumption has been linked to improved health, with decreased risks of diabetes, metabolic syndrome, and colon cancer. A group of scientists in Sweden found that lactoferricin4-14 (Lfcin4-14), a milk protein with known health effects, significantly reduces the growth rate of colon cancer cells over time by prolonging the period of the cell cycle before chromosomes are replicated. In a new study, investigators report that treatment with Lfcin4-14 reduced DNA damage in colon cancer cells exposed to ultraviolet (UV) light. Their results are published in the October issue of the Journal of Dairy Science®.
"We previously hypothesized that the prolongation of the cell cycle in colon cancer cells as a result of Lfcin4-14 treatment may give the cells extra time for DNA repair," says one of the lead investigators, Professor Stina Oredsson, of the Department of Biology at the University of Lund, Sweden. "Indeed, UV light-induced damage was decreased in colon cancer cells treated with Lfcin4-14 compared with controls. The differences were small but significant."
Investigators exposed colon cancer cells to UV light that caused DNA damage and then grew the cells in the absence or presence of Lfcin4-14. They evaluated DNA damage using a sensitive technique known as comet assay. After the cells are processed, the cells with DNA damage resemble a comet with a tail, and the intensity of the tail compared to the comet head indicates the number of DNA breaks. UV light exposure resulted in an increase in the number of comets while treatment with Lfcin4-14 reduced the number of comets in UV light-exposed cells.
To understand the mechanism by which Lfcin4-14 reduced DNA damage, investigators evaluated the levels of several proteins involved in cell cycle progression, DNA repair, and cell death. They found an increase in flap endonuclease-1, a protein associated with DNA synthesis; a decrease in b-cell lymphoma 2-associated X protein, which is involved with cell death; and a decrease in the level of g-H2AX, indicating more efficient DNA repair. "These changes in expression support our hypothesis that Lfcin4-14 treatment resulted in increased DNA repair," says Dr. Oredsson.
Dr. Oredsson notes that cancer cells, in general, have defects in the DNA repair mechanisms. Thus, Lfcin4-14 may have a greater effect on normal cells than on cancer cells. "Our data suggest that the effects of Lfcin4-14 in prolonging the cell cycle may contribute to the cancer preventive effect of milk. This must be further investigated in different systems," she concludes.
New study suggests
calcium and vitamin D may reduce cancer risk in women by at least 60 percent
Key milk nutrients, calcium and vitamin D, may do more than just help keep your bones strong. Increasing intake of calcium and vitamin D could reduce the risk for cancer in women by at least 60 percent, according to a new study published in the American Journal of Clinical Nutrition. (1)
The four-year clinical trial included more than one thousand women over the age of 55 in one of three supplement groups: 1) calcium (1400-1500mg) plus vitamin D (1100 IU vitamin D) 2) calcium only (1400-1500 mg) or 3) a placebo. The researchers found that the risk of developing cancer was 60 percent lower for those who took calcium and vitamin D and 47 percent lower for those taking calcium alone, compared to the placebo.
Fifty women developed nonskin cancer through the course of the four-year study, including breast, colon, lung and other cancers. When researchers excluded the 13 cancers diagnosed during first year of the study, determining these cancers were likely present at the study onset, the protective effect of calcium and vitamin D was even greater, with a 77 percent lower risk for cancer for those taking calcium plus vitamin D compared to the placebo.
With an estimated 10.5 million Americans living with cancer, researchers on a quest for new means to prevent or delay the occurrence of this deadly disease are encouraged by these findings.
“This is the first clinical trial to show that boosting vitamin D status can affect the overall risk for cancer – a proposition that has tremendous public health potential,” said lead author Dr Joan Lappe, a nutrition researcher from Creighton University in Omaha. “By choosing vitamin-D rich foods like milk and taking a supplement Americans can help improve their vitamin D levels and potentially impact their cancer risk.”
Milk is the primary source of calcium and an excellent source of vitamin D in the American diet. In fact, government reports indicate that more than 70 percent of the calcium in our nation’s food supply comes from milk and milk products. (2), (3), (4), (5) Additionally, milk is one of the few food sources of vitamin D, which is fast emerging as a “super nutrient.”
Several recent studies have reported similar conclusions, suggesting that calcium and vitamin D may reduce the risk for breast cancer in premenopausal women and colon cancer in older women. (6), (7)Together, these findings give Americans even more reason to meet the recommended three servings of lowfat or fat-free milk each day, providing 900 mg of calcium and 300 IU of vitamin D daily.
###
1) Lappe JM, Travers-Gustafson D, Davies KM, Recker RR, Heaney RP. Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial. American Journal of Clinical Nutrition. 2007;85:1586-1591.
2) Gerrior S, Bente L, Hiza, H. (2004). Nutrient Content of the U.S. Food Supply, 1909-2000. (Home Economics Research Report No. 56). U.S. Department of Agriculture, Center for Nutrition Policy and Promotion.
3) Dietary Guidelines for Americans 2005, U.S. Department of Agriculture, www.healtheirus.gov/dietaryguidelines.
4) Cotton PA, Subar AF, Friday JE, Cook A. Dietary sources of nutrients among US adults, 1994 to 1996. Journal of the American Dietetic Association. 2004; 104:921-930.
5) Weinberg L, Berner LA, Groves JE. Nutrient contributions of dairy foods in the United States, Continuing Survey of Food Intakes by Individuals, 1994-1996, 1998. Journal of the American Dietetic Association. 2004; 104:895-902.
6) Lin J, Manson JE, Lee I, Cook NR, Buring JE, Zhang SM. Intakes of Calcium and Vitamin D and Breast Cancer Risk in Women. Archives of Internal Medicine. 2007;167:1050-1059.
7) Feskanich D, Ma J, Fuchs CS, Kirkner GJ, Hankinson SE, Hollis BW, Giovannucci EL. Plasma vitamin D metabolites and risk of colorectal cancer in women. Cancer Epidemiology Biomarkers and Prevention. 2004;13:1502-1508.
Key milk nutrients, calcium and vitamin D, may do more than just help keep your bones strong. Increasing intake of calcium and vitamin D could reduce the risk for cancer in women by at least 60 percent, according to a new study published in the American Journal of Clinical Nutrition. (1)
The four-year clinical trial included more than one thousand women over the age of 55 in one of three supplement groups: 1) calcium (1400-1500mg) plus vitamin D (1100 IU vitamin D) 2) calcium only (1400-1500 mg) or 3) a placebo. The researchers found that the risk of developing cancer was 60 percent lower for those who took calcium and vitamin D and 47 percent lower for those taking calcium alone, compared to the placebo.
Fifty women developed nonskin cancer through the course of the four-year study, including breast, colon, lung and other cancers. When researchers excluded the 13 cancers diagnosed during first year of the study, determining these cancers were likely present at the study onset, the protective effect of calcium and vitamin D was even greater, with a 77 percent lower risk for cancer for those taking calcium plus vitamin D compared to the placebo.
With an estimated 10.5 million Americans living with cancer, researchers on a quest for new means to prevent or delay the occurrence of this deadly disease are encouraged by these findings.
“This is the first clinical trial to show that boosting vitamin D status can affect the overall risk for cancer – a proposition that has tremendous public health potential,” said lead author Dr Joan Lappe, a nutrition researcher from Creighton University in Omaha. “By choosing vitamin-D rich foods like milk and taking a supplement Americans can help improve their vitamin D levels and potentially impact their cancer risk.”
Milk is the primary source of calcium and an excellent source of vitamin D in the American diet. In fact, government reports indicate that more than 70 percent of the calcium in our nation’s food supply comes from milk and milk products. (2), (3), (4), (5) Additionally, milk is one of the few food sources of vitamin D, which is fast emerging as a “super nutrient.”
Several recent studies have reported similar conclusions, suggesting that calcium and vitamin D may reduce the risk for breast cancer in premenopausal women and colon cancer in older women. (6), (7)Together, these findings give Americans even more reason to meet the recommended three servings of lowfat or fat-free milk each day, providing 900 mg of calcium and 300 IU of vitamin D daily.
###
1) Lappe JM, Travers-Gustafson D, Davies KM, Recker RR, Heaney RP. Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial. American Journal of Clinical Nutrition. 2007;85:1586-1591.
2) Gerrior S, Bente L, Hiza, H. (2004). Nutrient Content of the U.S. Food Supply, 1909-2000. (Home Economics Research Report No. 56). U.S. Department of Agriculture, Center for Nutrition Policy and Promotion.
3) Dietary Guidelines for Americans 2005, U.S. Department of Agriculture, www.healtheirus.gov/dietaryguidelines.
4) Cotton PA, Subar AF, Friday JE, Cook A. Dietary sources of nutrients among US adults, 1994 to 1996. Journal of the American Dietetic Association. 2004; 104:921-930.
5) Weinberg L, Berner LA, Groves JE. Nutrient contributions of dairy foods in the United States, Continuing Survey of Food Intakes by Individuals, 1994-1996, 1998. Journal of the American Dietetic Association. 2004; 104:895-902.
6) Lin J, Manson JE, Lee I, Cook NR, Buring JE, Zhang SM. Intakes of Calcium and Vitamin D and Breast Cancer Risk in Women. Archives of Internal Medicine. 2007;167:1050-1059.
7) Feskanich D, Ma J, Fuchs CS, Kirkner GJ, Hankinson SE, Hollis BW, Giovannucci EL. Plasma vitamin D metabolites and risk of colorectal cancer in women. Cancer Epidemiology Biomarkers and Prevention. 2004;13:1502-1508.
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