Study: Effects of nutrition and nutritional supplements on the risk of prostate cancer

Reference

crystal AR, Arnold KB, Neuhouser ML, Goodman P, Square EA, Albanes D, Thompson im. Nutrition, intake of nutritional supplements and prostate cancer risk: Results of the study on prostate prevention. bin J epidemiol. 2010; 172 (5): 566-5770.

background

was a randomized, placebo-controlled study in which it was tested, whether finasteride, a 5-alpha reductase inhibitor that can reduce 7-year prevalence of prostate cancer. From 1993, 18,880 men aged ≥ 55 years were examined in the United States and Canada with normal results of the digital rectal examination (DRE); Values ​​of the prostate -specific antigen (PSA) of 3 ng/ml or less; And without history of prostate cancer, severe symptoms of the lower urinary tract or clinically significant comorbidities, and received either finasteride (5 mg/day) or placebo. During the PCPT, the men were subjected to a DRE and PSA determination annually, and participants with abnormal DRE results or a PSA value (adjusted to the effect of finasteride) of 4.0 ng/ml or more, a prostate tabiopsy was recommended. During the last attendance of study in the seventh year (2000–2003), all men who had previously been diagnosed with prostate cancer were offered a biopsy that consisted of at least 6 core samples that were found under Transrectal ultrasound control. The biopsies were examined both by the pathologist at the local place of study and a central pathological laboratory with full match for adenocarcinomas. The clinical stage was assigned locally and the tumors were classified centrally based on the Gleason evaluation system.

of the 18,880 participants were excluded 7,615 (40.3 %), in which no biopsy was carried out at the end of the study, including 1,225 men who died, 6,381 men who were unable to have a biopsy carried out or refused for medical reasons, and 9 who underwent a prostate as cancer for other reasons; There were 2,401 cases and 8,864 non -cases left. The researchers then excluded 173 cases that were diagnosed on or after the end date of the study (June 24, 2003), 92 cases that were diagnosed for 180 days or more after their planned degree, and 140 cases in which Gleason scores were missing. Of the men remaining for the study, the researchers also excluded 102 men who were missing data on the body mass index, 770 men who lacked nutritional data, and 429 men whose nutritional information was assessed due to a reported energy consumption of less than 800 as inaccessible, KCAL/day or more than 5,000 kal/day. Some men did not fill out the nutritional questionnaires because the doctors at their clinic location decided not to take part in the nutritional studies, or because prostate cancer was diagnosed before the questionnaire was given. This analysis was based on 1,703 cancer cases in 9,559 men.

participant

9,559 Canadian and American men

study parameters

Details on demographic and health -related features were collected with the help of self -completed questionnaires at the beginning of the study. The degree of physical activity was evaluated using a 6-point questionnaire. The size and weight were measured during the first visit to the clinic.

One year after the randomization, the participants filled a 15-page brochure with two questionnaires for nutrition and the use of nutritional supplements. With the help of a questionnaire to the frequency of food (Food Frequency Questionnaire, FFQ), the diet was evaluated, which was specially developed for this population of older men. The FFQ consisted of questions about 99 foods and 9 drinks as well as 18 questions about food preparation and 2 questions about eating fruit and vegetables. The participants stated the following on the questionnaire: the usual number of tablets that are taken per day for multivitamins and antioxidant mixtures; Both the number of pills taken a day and the dose for beta-carotene, vitamin C, vitamin E, calcium and zinc; And whether they have stress multi-multi-valley, vitamin D, fish oil or selenium at least three times a week. The multivita consumption and the additional intake of specific nutrients (the sum of individual nutritional supplements plus multivitamins) were as low (in accordance with no or rare use of a nutritional supplement), moderately (according to the quantities that are generally obtained from multivitals) and highly (accordingly) categorized to quantities that are generally only possible through highly dosed individual preparations). Since data for fish oil, selenium and vitamin D only templates whether these nutritional supplements were taken at least three times a week, fish oil was coded as 0 or 0.5 g Docosahexaenic acid (DHA) plus eicosapentaenic acid (EPA) per day, selenium was coded with 0 or 10 μg/day. The vitamin D content of multivitamins is also 10 µg; Therefore, men who took both multivitamins and individual vitamins were classified in the category of high -dose vitamin D.

In an inter- and intramethodic reliability study, which was carried out under 150 randomly selected men, we compared the nutrient absorption, which was calculated from the first FFQ, the recording from six 24-hour recalls, which was carried out the following year, and the recording from an additional FFQ that was completed according to all 24-hour recalls. One -hour recall actions were carried out. Based on the 128 men who have completed the study, the correlations between the first FFQ and the 24-hour memories (adjusted for energy and defuse measurement errors): total fat 0.71; polyunsaturated fat, 0.66; Simply unsaturated fat, 0.66; saturated fat, 0.75; Alcohol, 0.84; Carbohydrates, 0.70; Protein, 0.50; Vitamin C, 0.62; Lycopin, 0.58; Beta-carotene, 0.68; Vitamin D, 0.57; EPA + DHA, 0.87; Calcium, 0.62; and zinc, 0.51. The correlations between repeated FFQs were over 0.60 for all nutrients, with the exception of 0.54 for EPA + DHA.

most important knowledge

• cancer was found at 1,703/9,559 men, of which 127 had a high degree of illness (Gleason score 8 to 10).
• There was no evidence of a connection between the use of a certain nutrient and the overall risk for prostate cancer.
• The risk of high -grade prostate cancer was associated with a high absorption of polyunsaturated fats.
• food calcium was positively associated with the finding of a low -grade prostate cancer.
• Conversely, the intake of calcium in food was conversely associated with the finding of highly grade prostate cancer.
• The intake of polyunsaturated fatty acids was positively associated with the risk of high -grade cancer. There was no evidence that the diet or the use of nutritional supplements that are often used to prevent prostate cancer (e.g. lycopine, long-chain N-3 fatty acids, vitamin D, vitamin E, selenium), significantly influenced the risk of prostate cancer.

effects on practice

It has been shown that the use of an FFQ to assess the connection between the use of food/nutritional supplements and diseases has little meaning. FFQs can be recognized, but it does not use the food recordings of several days.

lycopin is a main component of tomatoes and is highly associated with a positive effect against prostate cancer. The addition with Lycopin had mixed results in the literature. It seems sensible to obtain lycopine from food, which could offer an additional synergistic value, and not from nutritional supplements that show inconsistent results in studies.

This study does not clarify what type of vitamin E the participants use. However, the study quotes the Select study, a large-scale population study, in which no reduced risks were found after a supplement with vitamin E, selenium or both. It is important to note that the vitamin E-type used in the Select study were exclusively alpha-tocopherol. In high doses, alpha-tocopherol “hurls the vital gamma tocopherol in the cells. While alpha tocopherol inhibits the production of free radicals, it is the gamma tocopherol form of vitamin E that is required to capture and neutralize free radicals. In a study published in the Proceedings of the National Academy of Sciences, researchers reported that it could be dangerous to take high quantities of alpha tocopherol vitamin E, without at the same time taking gamma-tocopherol. ^{4 The reason for this finding seems to be that too much alpha-tocopherol the cells from vitamin E could withdraw, which is needed to neutralize existing oxidizing agents such as the peroxynitrite radical, which can be particularly harmful. In a study carried out on the Johns Hopkins School of Public Health with 10,456 men, the likelihood of developing prostate cancer was five times lower for men with the highest gamma tocopherol blood level. In addition to the fact that higher Gamma tocopherol levels significantly reduced the risk of prostate cancer, the study also showed that selenium and alpha-tocopherol also reduced prostate cancer incidence, but only if the gamma tocopherol levels were high.}

With regard to calcium consumption, it is unclear why calcium from food is positive with the finding of prostate cancer with a low severity, but conversely, but was associated with the finding of prostate cancer with high severity.

With regard to calcium consumption, it is unclear why calcium from food was positive with the finding of prostate cancer with a low severity, but conversely, but was associated with the finding of prostate cancer with high severity. It is not defined whether those who took a calcium supplement also consumed some vitamin D3. At least in dairy products, calcium can increase the risk of prostate cancer by suppressing the concentrations of circulating 1,25-D. ^{6 All in all, dairy products seem to increase the overall risk of prostate cancer and should be avoided by prostate cancer patients or people with a family history of prostate cancer.}

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