A review of the weeks plant-based nutrition news 23rd August 2020
This week has a cancer theme as I am preparing for my talk for the International Plant-Based Nutrition Healthcare Conference.
The main headline messages from my talk are
At least 40% OF CANCER CASES COULD BE PREVENTED BY ADOPTING A HEALTHY DIET AND LIFESTYLE
Cancer prevention recommendations are done in my view. I doubt the advice will changing in the coming 5–10 years. I believe that the evidence supporting these recommendations will be further strengthened. The recommendations are summarised in an excellent guideline from the American Cancer Society and highlights are shown in my table below.
*mainly by increasing risk of weight gain
What is clear is that more and more studies continue to support these recommendations.
This paper just published shows once again how meat consumption is implicated in cancer development. The study analyzed data from 474 996 participants (54% women) in the UK Biobank study, followed for 7 years. Participants were aged 37–73 years and cancer-free at baseline. The results show that a 70g/day higher intake of red and processed meat was associated with a 20–40% increased risk of colorectal cancer. Although the association was less robust, red meat consumption was shown to increase the risk of prostate cancer by 18%. The data also suggested increased risk for breast cancer (10–14%) and endometrial cancer (30–48%) with higher intakes of meat, but these associations were attenuated after adjustment for BMI, suggesting overweight/obesity are likely to be causing the association. In addition, a 20% increase in risk of cancer of the lymphatic and haematopoietic tissue was found with poultry intake, although the results did not hold true after correcting for multiple testing. So once again — moderation is not the answer. 70g of processed meat is only 2 slices of bacon or 1.5 sausages.
LIFESTYLE TRUMPS GENETICS EVERY TIME
This paper again from the UK biobank prospective cohort study, included 2728 women with breast cancer and 88 489 controls, and investigated the impact of lifestyle factors on the genetic risk for breast cancer. Classification of healthy lifestyle was based on Cancer Research UK guidance and included healthy weight, regular exercise, no use of HRT for more than 5 years, no oral contraceptive use, and alcohol intake <3 times/week. The genetic contribution for breast cancer was estimated using a polygenic risk scores of 305 preselected single nucleotide variations. After a median follow up of 10 years, for every level of genetic risk, healthy lifestyle factors significantly reduced the risk of breast cancer in the order of 40–90%.
NUTRITION DURING CANCER TREATMENT DOES MATTER BUT WE ARE NOT DOING SUCH A GREAT JOB.
Although this study is from 2013, my personal experience is that things have not improved significantly. Of the 21 National Comprehensive Cancer Network institutions from the US surveyed, only four (19%) provided dietary recommendations for patients undergoing cancer treatment. Five institutions (24%) referenced external websites for the information. Overall, guidance lacked consistency.
A personal bugbear of mine is the continued use of ‘neutropenic diets’ in patients receiving intensive anti-cancer treatment that is likely to cause a low neutrophil count. These diets are restrictive and may exclude some very healthy plant foods. This is despite the conclusion of a 2019 systematic review and meta-analysis that concluded there was no difference between a neutropenic diet and regular diet in terms of infections or mortality in patients with chemotherapy-induced neutropenia. In fact, the data demonstrated a slight increase in infection rates in patients under-going stem cell transplant when applying food restriction. The authors make a bold conclusion ‘There is currently no evidence to support the use of neutropenic diet or other food restrictions in neutropenic patients with cancer’. The message given to patients is often about only eating fruits and vegetables you can peel and this results in patients avoiding many healthy foods.
THE HEALTH OF OUR GUT MICROBIOME IS IMPORTANT TO HOW WE RESPOND TO CERTAIN ANTI-CANCER TREATMENTS
52 patients with solid tumour treated with immunotherapy were included in this study and short chain fatty acids (SCFA) were measured in plasma and faeces. Diet information was also analysed. With a median follow up of 2 years, higher levels of SCFAs were associated with a longer remission. High fibre foods, including green vegetables, cabbage, and mushrooms, were associated with higher concentrations of faecal SCFAs. High frequency of mushroom intake was associated with a better response to treatment. SCFA’s are produced by healthy gut bacteria and integral to maintaining a healthy gut lining, reducing inflammation and maintaining a healthy immune system both in the gut and the rest of the body.
CANCER TREATMENTS CAN INCREASE THE RISK OF OTHER CHRONIC ILLNESSES
This systematic review and meta-analysis included 6,962 patients with breast cancer treated with tamoxifen and 975 patients not treated with tamoxifen. The data show that tamoxifen increases the risk of non-alcoholic fatty liver disease, with a prevalence of 40% in women taking tamoxifen. This was a 3 times increased risk compared to patients with breast cancer not taking tamoxifen. The main risk factors identified were greater body mass index and high cholesterol levels suggesting that a healthy diet and lifestyle are important after a cancer diagnosis to reduce side effects of anti-cancer medications.
A HEALTHY DIET AFTER CANCER TREATMENT CAN ALSO MAKE A BIG DIFFERENCE
The good news is that even after a diagnosis of cancer, a healthy diet can improve your chances of survival. This paper reports data from the Women’s Health Initiative study, which included 48,835 postmenopausal women, aged 50–79 years. Parcipants were randomly assigned to a low-fat diet intervention with increased consumption of fruits, vegetables and whole grain, or their usual diet. Even though a low fat diet of <20% calories from fat was not achieved by the participants in the intervention group, the study showed that those who developed breast cancer and ate more fruits, vegetables and whole grains lived longer after the diagnosis. The authors conclude ‘Adoption of a low-fat dietary pattern associated with increased vegetable, fruit, and grain intake, demonstrably achievable by many, may reduce the risk of death as a result of breast cancer in postmenopausal women’.
So, all in all, I am spoilt for choice for my talk at the upcoming conference, when I will be sharing much more exciting data on diet and lifestyle for cancer.
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