Nutritional advice

Objectives:
Does consumption of fruits and vegetables reduce risk of endometrial cancer?

Study design:
This review article included  of 21 case-control studies and 6 cohort studies.

Results and conclusions:
The investigators found that vegetables consumption significantly reduced risk of endometrial cancer with 24% [pooled odds ratio [OR], relative risk [RR], hazard ratio [HR] = 0.76, 95% CI = 0.63 to 0.91].

The investigators found that cruciferous vegetables consumption significantly reduced risk of endometrial cancer with 19% [pooled OR = 0.81, 95% CI = 0.70 to 0.94].

The investigators found that dark green and yellow/orange combined vegetables consumption significantly reduced risk of endometrial cancer with 36% [pooled OR = 0.64, 95% CI = 0.42 to 0.97].

The investigators found that fruits consumption significantly reduced risk of endometrial cancer with 19% [pooled OR = 0.81, 95% CI = 0.70 to 0.92].

The investigators found these results were primarily based on studies of high quality and exhibited either by case-control only or a combination of case-control and cohort studies. Additionally, the results varied by geographic location, such as Western areas, the US and Italy.

The investigators concluded that consumption of fruits and vegetables has beneficial effects on endometrial cancer risk and that specific kinds of fruits and vegetables should be recommended differently due to their outstanding bioactive components.

Original title:
The influence of dietary vegetables and fruits on endometrial cancer risk: a meta-analysis of observational studies by Lu YT, Gunathilake M and Kim J.

Link:
https://pubmed.ncbi.nlm.nih.gov/36151331/

Additional information of El Mondo:
Find more information/studies on cancer and fruit and vegetable consumption right here.

Objectives:
There is keen interest in better understanding the impacts of alpha-linolenic acid (ALA), a plant-derived n-3 fatty acid, in ameliorating the development of cancer. However, results of several prospective cohort studies present an inconsistent association between ALA intake and the incident colorectal cancer (CRC). Therefore, this review article has been conducted.

Does a high dietary intake of alpha-linolenic acid or a high level of alpha-linolenic acid in blood reduce risk of colorectal cancer (colon and rectal cancer)?

Study design:
This review article included 15 cohort studies (11 studies on diet and 5 studies on biomarkers including 4 on blood and 1 on adipose tissue) with 12,239 colorectal cancer cases occurred among 861,725 participants.
The mean follow-up was 9.3 years (ranging from 1 to 28 years).
Among all of the included studies, quality scores assessed by the 9-star NOS ranged from 7 to 9, with a median quality (≤7 stars) in 2 studies and high quality (≥ 8 stars) in 13 studies.

There was no publication bias.

Results and conclusions:
The investigators found higher level of alpha-linolenic acid in blood significantly reduced risk of colorectal cancer with 17% [summary RR = 0.83, 95% CI = 0.69 to 0.99, I2 = 0.0%].

The investigators found each 0.1% increase in the level of alpha-linolenic acid in blood was significantly associated with a 10% reduction in colorectal cancer risk [summary RR = 0.90, 95% CI = 0.80 to 0.99, I2 = 38.6%].

The investigators no significant dose-response association between dietary intake of alpha-linolenic acid and the incident colorectal cancer [p for non-linearity = 0.18; p for linearity = 0.24].

The investigators concluded that higher blood levels of alpha-linolenic acid reduce risk of colorectal cancer while higher dietary intake of alpha-linolenic acid does not reduce risk of colorectal cancer. Encouraging the consumption of foods rich in alpha-linolenic acid to improve its levels in the blood may potentially decrease the risk of colorectal cancer. Nevertheless, well-designed and large-scale cohort studies with biomarkers are still needed for better reconfirming the potential impacts of alpha-linolenic acid intake in the primary prevention of colorectal cancer.

Original title:
Association of Dietary Intake and Biomarker of α-Linolenic Acid With Incident Colorectal Cancer: A Dose-Response Meta-Analysis of Prospective Cohort Studies by Dai ZB, Ren XL, […], Xu L.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9301188/

Additional information of El Mondo:
Find more information/studies on colorectal cancer and alpha-linolenic acid consumption right here.

Objectives:
Colorectal cancer is one of the most commonly diagnosed and deadly cancers worldwide. Epidemiological studies on the relationship between folate intake and the risk of colorectal cancer have reported inconsistent findings since folate fortification in the USA. Therefore, this review article has been conducted.

Does a high folate (folic acid) ietary intake reduce risk of colorectal cancer (colon and rectal cancer)?

Study design:
This review article included 24 cohort studies involving 6,165,894 individuals, of which 37,280 persons with colorectal cancer.

Results and conclusions:
The investigators found compared with the lowest dietary intake, the highest folate dietary intake significantly reduced risk of colorectal cancer with 12% [combined relative risk (RR) = 0.88, 95% CI = 0.83 to 0.92, p = 0.0004].
Significantly means that there is an association with a 95% confidence.

The investigators found compared with the lowest dietary intake, the highest folate dietary intake significantly reduced risk of colorectal cancer with 3% among persons witih medium alcohol consumption [RR = 0.97, 95% CI = 0.96 to 0.99, p = 0.008].
Significantly because RR of 1 was not found in the 95% CI of 0.96 to 0.99. RR of 1 means no risk/association.

The investigators found compared with the lowest dietary intake, the highest folate dietary intake significantly reduced risk of colorectal cancer with 5% among persons witih high alcohol consumption [RR = 0.95, 95% CI = 0.92 to 0.97, p = 0.003].

The investigators found compared with the lowest dietary intake, the highest folate dietary intake did not reduce risk of colorectal cancer among non-drinkers [RR = 1.00, 95% CI = 0.98 to 1.02, p = 0.827].

The investigators found compared with the lowest dietary intake, the highest folate dietary intake significantly reduced risk of colon cancer with 14% [RR = 0.86, 95% CI = 0.81 to 0.92, p = 0.0004].
Significantly because the calculated p-value of 0.0004 was less than the p-value of 0.05.

The investigators found compared with the lowest dietary intake, the highest folate dietary intake did not reduce risk of rectal cancer [RR = 0.92, 95% CI = 0.84 to 1.02, p = 0.112].

The investigators found compared with the lowest dietary intake, the highest folate dietary intake significantly reduced risk of colorectal cancer in USA and Europe but not in other regions.

The investigators concluded that high folate dietary intake reduces risk of colon cancer, particularly in people with medium or high alcohol consumption, but it still needs to be further confirmed.

Original title:
Folate intake and risk of colorectal cancer: a systematic review and up-to-date meta-analysis of prospective studies by Fu H, He J, […], Chang H.

Link:
https://pubmed.ncbi.nlm.nih.gov/35579178/

Additional information of El Mondo:
Find more information/studies on colorectal cancer and folic acid consumption right here.

Colorectal cancer starts in the colon or the rectum. These cancers can also be called colon cancer or rectal cancer, depending on where they start.

Objectives:
The association between meat intake and hepatocellular carcinoma (HCC) risk is still unclear. Therefore, this review article has been conducted.

Does a higher dietary intake of meat increases the risk of hepatocellular carcinoma?

Study design:
This review article included 17 observational studies involving 2,915,680 participants, of which 4,953 cases of hepatocellular carcinoma.

10 studies reported red meat intake, 9 reported white meat intake, 9 reported fish intake, 7 reported processed meat intake and 5 reported total meat intake.

Results and conclusions:
The investigators found results showed that the consumption of red meat [relative risk = 1.04, 95% CI = 0.91 to 1.18, I2 = 50.50%, p = 0.033] and total meat intake [relative risk = 1.01, 95% CI =  0.90 to 1.13, I2 = 15.50%, p = 0.316] were not significantly associated with risk of hepatocellular carcinoma.

The investigators found, however, a higher dietary intake of processed meat significantly increased the risk of hepatocellular carcinoma with 20% [relative risk = 1.20, 95% CI = 1.02 to 1.41, I2 = 26.30%, p = 0.228].
Significant because relative risk of 1 was not found in the 95% CI of 1.02 to 1.41. Relative risk of 1 means no risk/association.

The investigators found, in contrast, a higher dietary intake of white meat significantly decreased the risk of hepatocellular carcinoma with 24% [relative risk = 0.76, 95% CI = 0.63 to 0.92, I2 = 68.30%, p = 0.001].

The investigators found, in contrast, a higher dietary intake of fish significantly decreased the risk of hepatocellular carcinoma with 9% [relative risk = 0.91, 95% CI = 0.86 to 0.96, I2 = 40.90%, p = 0.095].

The investigators concluded that a higher dietary intake of processed meat increases the risk of hepatocellular carcinoma, while a higher dietary intake of both white meat and fish decrease the risk of hepatocellular carcinoma. Therefore, these findings suggest that dietary intervention may be an effective approach to preventing hepatocellular carcinoma. These need to be verified with further well-designed observational studies and experimental clinical research.  

Original title:
Meat Intake and the Risk of Hepatocellular Carcinoma: A Meta-Analysis of Observational Studies by Yu J, Liu Z, […], Chen W.

Link:
https://pubmed.ncbi.nlm.nih.gov/35583453/

Additional information of El Mondo:
Find more information/studies on cancer and meat consumption right here.

Processed meats are meats that have been preserved by smoking or salting, curing or adding chemical preservatives. They include deli meats, bacon and hot dogs.

Objectives:
Evidence associating diet with the incidence of renal cell carcinoma (RCC) is inconclusive. Therefore, this umbrella review article has been conducted.

What is the association between diet and renal cell carcinoma incidence?

Study design:
This umbrella review article included 22 meta-analyses with a total of 502 individual studies and 64 summary hazard ratios (HRs) for renal cell carcinoma incidence: dietary patterns or dietary quality indices (n = 6), foods (n = 13), beverages (n = 4), alcohol (n = 7), macronutrients (n =15) and micronutrients (n =19).

No meta-analyses had high methodological quality.

59% of these 502 individual studies were cohort studies (n = 298), 39% were case-control studies (n = 196) and 2% were pooled studies (n = 8).

Sixty (94%) exposures in the included meta-analyses had more than 1,000 cases or 20,000 participants.

Results and conclusions:
The investigators found no dietary factors showed convincing or highly suggestive evidence of association with renal cell carcinoma incidence in the overall analysis.

The investigators found in the overall analysis that dietary intake of vegetables significantly reduced risk of renal cell carcinoma with 26% [summary HR = 0.74, 95% = 0.63 to 0.86, suggestive evidence].

The investigators found in the overall analysis that dietary intake of vitamin C significantly reduced risk of renal cell carcinoma with 23% [summary HR = 0.77, 95% = 0.66 to 0.90, suggestive evidence].

The investigators found in the overall analysis that moderate drinking significantly reduced risk of renal cell carcinoma with 23% [summary HR = 0.77, 95% = 0.70 to 0.84, convincing evidence] in Europe and North America.

The investigators found in the overall analysis that dietary intake cruciferous vegetables significantly reduced risk of renal cell carcinoma with 22% [summary HR = 0.78, 95% = 0.70 to 0.86, highly suggestive evidence] in North America.

The investigators concluded dietary intake of vegetables and vitamin C could reduce renal cell carcinoma risk. Moderate drinking might be beneficial for Europeans and North Americans and cruciferous vegetables might be beneficial to North Americans, but the results should be interpreted with caution because no meta-analyses had high methodological quality. More researches are needed in the future.

Original title:
The role of diet in renal cell carcinoma incidence: an umbrella review of meta-analyses of observational studies by Liao Z, Fang Z, […], Luo Z.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8812002/

Additional information of El Mondo:
Find more information/studies on cancer, vegetables, vitamin C right here.

An umbrella review article is a scientific article which only includes meta-analyses (also called review articles). The results found in an umbrella review article are more reliable than found in an individual review article.

One swallow does not make a summer. A famous Dutch saying that could not be any more obvious. Just because one single scientific study about a certain topic makes certain claims, it does not necessarily mean it is true. On the other hand, a review article (a collection of scientific studies on a certain topic) of randomized, placebo-controlled double blind clinical trials (RCTs) will answer the following question:
"Do taking dietary supplements make sense?" Yes for a positive conclusion and no for a negative conclusion.

One swallow does not make a summer. A famous Dutch saying that could not be any more obvious. Just because one single scientific study about a certain topic makes certain claims, it does not necessarily mean it is true. On the other hand, a review article (a collection of scientific studies on a certain topic) of (prospective) cohort studies or case-control studies will answer the following question:
"Should I change my diet?".

Objectives:
Does a high olive oil consumption reduce cancer risk?

Study design:
This review article included 37 case-control studies with 17,369 cases (persons with cancer) and 28,294 controls (persons without cancer) and 8 cohort studies with 12,461 incident cases among 929,771 subjects (participants).

Significant publication bias was detected via Egger’s test in the analysis on overall cancer risk [p 0.001], breast cancer [p = 0.013] and gastrointestinal cancer risk [p = 0.048].

Results and conclusions:
The investigators found in pooled analysis of case-control and cohort studies that highest olive oil consumption was significantly associated with a 31% lower risk of any cancer [pooled RR = 0.69, 95% CI = 0.62 to 0.77].  
Significantly means that there is an association with a 95% confidence.

The investigators found subgroup analyses showed that the protective effect of high olive oil consumption in terms of cancer risk was also significant in case-control studies [37 study arms, RR = 0.65, 95% CI = 0.57 to 0.74] but not in cohort studies [8 study arms, RR = 0.90, 95% CI = 0.77 to 1.05].
Furthermore, the protective association was also found in a multivariate analysis [32 study arms, RR = 0.72, 95% CI = 0.65 to 0.81], a high study quality analysis [RR = 0.72, 95% CI = 0.64 to 0.81], Mediterranean participants [RR = 0.69, 95% CI = 0.60 to 0.79] and non-Mediterranean participants [RR = 0.49, 95% CI = 0.34 to 0.71].

The investigators found in pooled analysis of case-control and cohort studies that highest olive oil consumption was significantly associated with a 33% lower risk of breast cancer [pooled RR = 0.67, 95% CI = 0.52 to 0.86].  
Significantly because RR of 1 was not found in the 95% CI of 0.52 to 0.86. RR of 1 means no risk/association.

The investigators found subgroup analyses showed that the beneficial effect was reproducible in case-control studies [RR = 0.63, 95% CI = 0.45 to 0.87] but not in cohort studies.
Furthermore, high olive oil consumption was linked to a reduced breast cancer risk in Mediterranean [RR = 0.67, 95% CI = 0.49 to 0.92] and non-Mediterranean populations [RR = 0.25, 95% CI = 0.07 to 0.89].

The investigators found in pooled analysis of case-control and cohort studies that highest olive oil consumption was significantly associated with a 23% lower risk of gastrointestinal cancer [pooled RR = 0.77, 95% CI = 0.66 to 0.89].  
Subgroup analyses showed an inverse relationship between highest olive oil consumption and risk for esophageal cancer [RR = 0.47, 95%CI = 0.24 to 0.93] and pancreatic cancer [RR = 0.58, 95% CI = 0.35 to 0.97].
Furthermore, significant effects were also found in case-control studies [RR = 0.72, 95% CI = 0.61 to 0.85), studies within the Mediterranean area [RR = 0.77, 95% CI = 0.67 to 0.88], multivariate analyses [RR = 0.76, 95% CI = 0.63 to 0.90] and high quality studies [RR = 0.73, 95% CI = 0.62 to 0.86].

The investigators found in pooled analysis of case-control and cohort studies that highest olive oil consumption was significantly associated with a 26% lower risk of upper aerodigestive cancer [pooled RR = 0.74, 95% CI = 0.60 to 0.91].  
Subgroup analyses showed results remained significant for case-control studies [RR = 0.74, 95% CI = 0.60 to 0.91], multivariate analyses [RR = 0.75, 95% CI = 0.66 to 0.86] and studies of high quality [RR = 0.68, 95% CI = 0.52 to 0.89].

The investigators found in pooled analysis of case-control studies that highest olive oil consumption was significantly associated with a 54% lower risk of urinary tract cancer [pooled RR = 0.46, 95% CI = 0.29 to 0.72].  
Subgroup analyses showed results remained significant for studies of high quality [RR = 0.46, 95% CI = 0.32 to 0.66].

The investigators concluded highest versus lowest olive oil consumption is associated with 31% lower cancer risk, especially for breast, overall gastrointestinal, upper aerodigestive and urinary tract cancer. Additional prospective cohort studies on various cancer types, especially in non-Mediterranean regions, as well as large randomized trials, seem desirable in order to provide further insight into the role of olive oil in preventing cancer.

Original title:
Olive oil intake and cancer risk: A systematic review and meta-analysis by Markellos C, Ourailidou ME, […], Psaltopoulout T.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8751986/

Additional information of El Mondo:
Find more information/studies on cancer, olive oil consumption right here.

The conclusions in scientific studies are even more reliable when they are also found in cohort studies, multivariate analyzes (studies where adjustments were made for multiple confounding factors) and high-quality studies.
 

Objectives:
Does postoperative coffee or caffeine consumption causally reduce risk of postoperative ileus (POI) in patients undergoing elective colorectal surgery?

Study design:
This review article included 4 RCTs with 312 subjects.

Results and conclusions:
The investigators found postoperative coffee or caffeine consumption significantly decreased the time to first bowel movement [MD = -10.36 h, 95% CI = -14.61 to -6.11], shortened the length of hospital stay [MD = -0.95 days, 95% CI = -1.57 to -0.34] and was significantly  associated with a 36%-decreased risk of the use of any laxatives after the procedure [RR = 0.64, 95% CI = 0.44 to 0.92].

The investigators found the time to first flatus, time to tolerance of solid food, risk of any postoperative complication, postoperative reinsertion of a nasogastric (NG) tube and anastomotic leakage showed no statistical differences between groups.

The investigators concluded postoperative coffee or caffeine consumption causally improves bowel movement and decreases the duration of hospital stay in patients undergoing elective colorectal surgery. This method is safe and can prevent or treat postoperative ileus (POI).

Original title:
The effect of coffee/caffeine on postoperative ileus following elective colorectal surgery: a meta-analysis of randomized controlled trials by Yang TW, Wang CT, […], Tsai MC.

Link:
https://pubmed.ncbi.nlm.nih.gov/34993568/

Additional information of El Mondo:
Find more information/studies on caffeine and cancer right here.

Postoperative ileus is a prolonged absence of bowel function after surgical procedures, usually abdominal surgery.