Questions about cancer and nutrition with Senior Research Dietitian Barbara Parry

1. Quite a few of our members have arthritis after cancer treatments. Is the any type of food or supplement which could help alleviate symptoms?

  • It’s easy to assume that just changing one food or adding in one supplement is the answer but joint pain and inflammation is a complex process, just as breast cancer is a complex disease.
  • As a breast cancer specialist dietitian I’m not a diet and arthritis expert – my understanding is that this joint pain is a side-effect of some of the very effective breast cancer treatments prescribed.
  • There is likely benefit from adopting a plant-based way of eating, however, as this increases dietary sources of anti-oxidants and anti-inflammatory components in foods and beverages.  Similarly eating in a low fat way, reducing body fat stores, through a healthy eating approach and regular physical activity reduces inflammation generally in the body in particular by encouraging the mobilization of fat stored around organs and in muscle tissue.

2. Are there any basic supplements that all post treatment ladies should consider taking

  • There are no health advantages to taking supplements for the sake of taking supplements, as they are designed to be taken most appropriately when indicated eg:  there is an abundance of evidence in the literature that shows people who take supplements are those already meeting all nutritional needs by following a healthy eating pattern (they are already tuned into the “healthy messages”; and so supplementation is actually an unnecessary expense).
  • There is a large industry out there of supplement manufacturers which are keen to establish themselves a customer base and which claim some health benefits (often worded very generally) in marketing materials.
  • The best source of nutrients comes from whole foods and not from extracted nutrients or lab-manufactured nutrients put into tablet or tonic form.  For dietary components like phytochemicals known to be beneficial (eg: iso-thiocyanates from the glucosinolates in watercress and like the curcumin from turmeric) putting it into a tablet does not guarantee it will be absorbed nor will you benefit from the many other nutritional components of that food.
  • The one supplement I do recommend, on the basis that the entire population is likely to have sub-optimal status, is VITAMIN D.  Public Health England recommend we all take a 10microgram supplement daily (equivalent to 400 International Units) especially during the winter months.  There is also the suggestion in the research literature that vitamin D is important for improving breast cancer treatment outcomes and reducing risk of recurrence so there may be particular benefits for women after a breast cancer diagnosis.
  • Good food sources of vitamin D include:  oily fish, fortified breakfast cereals, some fortified yoghurt (like Cal-in plus) and eggs.

3. Alcohol has been shown to have a significant effect on breast cancer for post-menopausal women, particularly for hormone receptive cancers.  Is it therefore advisable to have no alcohol, or are one or two drinks each week acceptable?  Is there any advantage/disadvantage to having wine, beer, spirits or cider?

  • Alcohol is defined as a carcinogen (able to produce cancer in the body) by the World Health Organisation, in particular in susceptible individuals.  Our genes hold the answer to whether we are one of those susceptible individuals or not and (being a multi-factorial condition) cancer is perhaps unlikely to occur if you only have one risk factor out of the many.
  • If a non-drinker at the time of diagnosis, the advice is don’t start.  If you like alcohol, aim to have alcohol free days and limit your intake to a maximum of one or two units in any one day.
  • There is again not a simple explanation about whether one type of alcoholic beverage is better than another.  Possible sources of anti-oxidants like resveratrol in red wine may be beneficial despite the alcohol content but this is not really certain.  The latest WCRF UK Breast Cancer Continuous Update Programme report (published in June 2017) states:

“The evidence that alcohol increases risk of pre and postmenopausal breast cancer – by 7-12% per 10g ethanol – was generally consistent.  Consumption of alcoholic drinks is a convincing cause of postmenopausal breast cancer.  Limited but suggestive evidence of a stronger relationship between alcohol and ER+ sub-types of breast cancer.”

4. Dairy foods were shown to have a limited impact on post-menopausal women, but foods high in calcium may decrease the risk.  Surely diary is one of the main sources of calcium, so this is slightly contradictory?  What foods are the best source of calcium?

Quotes from the CUP (2017):  “The evidence suggesting that consumption of dairy foods decreases the risk of premenopausal breast cancer is limited.”  “The evidence suggesting that consumption of dairy foods decreases the risk of postmenopausal breast cancer is limited.”  “The evidence suggesting that diets rich in calcium decrease the risk of pre- and post-menopausal breast cancer is limited.”

  • Enjoy low fat dairy foods as they are a quality source of dietary calcium, is the message.  Control intake of dairy foods so that you consume enough to meet calcium needs (RNI 700mg daily) but not excessively such that energy intake may exceed requirements.
  • In addition to dairy sources, non-dairy sources include fortified soya and nut milks, some dark green leafy vegetables, nuts and seeds (although caution as these are high in fat), some fruits (such as dried apricots and oranges), beans and lentils, soft boned fish (like tinned sardines), tofu (because bean curd is formed by adding an acid, like lemon juice, and a calcium salt to the boiled soya milk).

5. Sugar is currently considered to increase cancer risk, although there is no specific mention of this in the 2017 global report on diet, nutrition, physical activity and breast cancer.  Is it just processed sugar that should be avoided, or does this impact on the intake of fresh and dried fruit too?

  • Sugar is not explicitly mentioned in the global report because there is no convincing evidence that this is the case.  That is not to say that there is no reason to reduce “processed sugar” and other highly refined carbohydrate (officially referred to as “non-milk extrinsic sugars”) to improve dietary intake and quality of food choice.
  • Sugar provides “empty calories” but can be useful to allow energy needs to be met by concentrating nutrition into smaller portion sizes when appetite is poor, as can sources of dietary fat.  Every gram of sugar provides 4Calories, every gram of fat provides 9Calories.
  • The “sugar fuels cancer” headline is a serious oversimplification of the evidence.  There is limited evidence that a carbohydrate-restricted diet is helpful in a rare hard-to-treat brain cancer in children with some evidence of delayed progression of the disease.  That does not mean, however, that such an approach is the answer for all cancers nor that it is sugar that fuels cancer.  Whilst there is evidence that cancer cells change the way they metabolise glucose, glucose is an essential fuel source for healthy cells and the body can meet its needs by including unrefined sources of carbohydrate in a healthy eating pattern – there is no nutritional need for “added sugar” foods per se.  Fresh fruit or dried fruit can be a source of this unrefined carbohydrate (and also be a source of other nutrients too!).

6. Is there any advantage to consuming organic foods?

  • If comparing foods in season grown “organically” or “conventionally” there has been some limited evidence that the nutrient profile of the organically grown varieties is better.  However, foods eaten out of season are likely to have travelled many hundreds of miles before they reach the supermarket shelves – hence there will be nutrient losses.  And this is the case whether they are labelled as “organic” or not.
  • There is an agricultural standard (from the Soil Association) to define “organic” in the UK but different countries may well employ different legislation allow the products to be so called.
  • It can be reassuring when a critical diagnosis makes you feel vulnerable to opt for what is perceived as “more natural” but what really do we mean by “natural”.  All our health promoting foods are made up of chemicals (all of which are naturally occurring) and yet, if we saw them listed on a label, we’d assume they were artificial e-numbers!  We perceive risk in a different way after the shock of a cancer diagnosis and having gone through treatment.
  • There is a price premium associated with the organic label and it is best to eat a plant-based diet generally rather than be limited to eating a little organic fruits and vegetables because they are too expensive.
  • Being reassured about the nutritional benefits of plant-based eating can also lower circulating stress hormones and this is associated with reducing one of the potential risk factors for diseases such as cancer.  Perhaps we are getting closer to understanding why a positive approach to healthy eating and regular physical activity can offer further benefits as a strategy for “stress management”.

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