Is breast cancer programmed by childhood diet?
Several studies covered in Cancer Watch over recent years have suggested that weight, growth rates and early onset of puberty in girls may be linked to breast cancer later in life. A 2012 study showed that drinking a lot of milk in adolescence was linked to prostate cancer later in life too.
Here Gosia Desmond, Director in Nutrition and a lecturer at The College of Naturopathic Medicine in the UK and in Ireland, looks at what lies behind this.
A new area of nutrition research, called Nutrition Programming, brings new insights into the origins of chronic disease in adult life. It suggests that the risk of obesity, diabetes, cardiovascular disease and some types of cancer can be programmed in childhood through nutritional manipulation. The topic is vast but it is clear that diet can affect your childs future health through numerous mechanisms controlled by micronutrient deficiencies or excesses, food pesticide residues and many others.
The evidence that breast cancer is affected by diet in childhood is strong. Surprisingly, it is not nutritional deficiencies or chemical residues of food, but the basic nutrient that each child needs for growth and development protein which seems to play the most fundamental role in the nutrition programming of breast cancer.
Events in childhood are linked to adult breast cancer risk
Breast cancer is a major cause of death in women. Over the last thirty years in Britain, the incidence rate of this disease increased by more than half from 77 per 100,000 in 1978 to 120 per 100,000 in 2007 and it is expected to reach 124 per 100,000 in 2024. At the same time, the age of female puberty has been progressively declining. In the 19th century most girls had their first period in their late teens. Currently it is not uncommon for girls to begin menstruating before the age of 10. Early menarche is an established risk factor for adult breast cancer with each year of menarche delay decreasing the risk by 10-20%.
Researchers believe that this rapid decline in puberty age is not down to our genes. Early menarche results from a combination of factors that we can, ourselves, control leading to rapid childhood growth and increasing Body Mass Index (BMI).
Studies suggest that the two strongest predictors of early menarche are
a) the annual growth rate in height between 4 and 7 years of age, and
b) higher rates of BMI between birth and 7 years of age.
In other words, taller and heavier children tend to be faster to mature. They also tend to have, what is called earlier adiposity rebound, (an increase in BMI that follows a steady decline after the first year of life - adiposity rebound occurs between 3 and 7 years of age, and the later your daughter experiences it, the smaller her risk of early menarche).
Premature adiposity rebound and greater height in childhood is also linked to higher adult BMI. An American study revealed that the tallest 15 per cent of children had 5 times the risk of obesity compared to children shorter than the norm.
Body Mass Index (BMI): is an inexpensive and easy way to estimate a healthy body weight based on a person’s height, assuming an average body composition. It is defined as the body weight in kilograms divided by the square of height in meters. High BMIs are therefore indicative of higher weight for your height.
Dairy consumption and increased levels of hormones
So lets look at how nutrition can influence the timing of puberty. The rate of growth pre-puberty is controlled mostly by the hormones Insulin, Insulin-like Growth Factor 1 (IGF-1) and later by Growth Hormone. Taller children have higher levels of IGF-1 in their blood than smaller children with a 20% difference between the tallest and the smallest child. Faster growing children also have higher blood levels of insulin. Additionally, high Insulin and IGF-1 levels seem to accelerate the timing of sexual maturation, possibly by decreasing the amount of bound (and inactive) sex hormones thus increasing the pool of free and active sex hormone levels.
Until recently it was assumed that a high-fat, low-fibre diet was the main nutritional factor promoting early growth spurt and menarche. However, recent evidence suggests that out of all dietary components, animal protein found in meat, eggs and dairy products, has the strongest effect on serum Insulin, IGF-1, and Growth Hormone levels and therefore growth, and sexual maturation.
Milk protein consumption increases the blood levels of Insulin and IGF-1 almost immediately after the meal. This should not be surprising as the main purpose of milk of any mammal species is to promote growth. Clear evidence of the growth-promoting effect of milk came from studies in developing countries where, against a background of poor nutrition, an increase in intake of animal and dairy protein was shown to stimulate weight gain and height in infancy, childhood, and adolescence.
However, milk and milk protein consumption causes acceleration of linear growth and body height in children from industrialised countries as well, where intake of dietary protein is already substantially above their physiological requirements. Infants who are fed formula based on cows milk, grow at a faster rate than breastfed infants especially during the latter half of infancy. Danish scientists demonstrated that an increase in milk intake from 1 to 3 cups a day corresponded to a 30 per cent increase in circulating IGF-1 in 2.5 year old children with consequences for subsequent growth. In another Danish study, a higher intake of milk (1.5 litre per day) increased serum IGF-1 and Insulin levels among 8-year old boys by 19 per cent and 103 per cent respectively within just 7 days. Recently, an intervention study of Mongolian 10-year old children demonstrated that consumption of 3 cups of whole milk a day increased serum IGF-1 by 23 per cent in just 4 weeks.
Meat and fish protein and hormone levels
It is interesting to note that meat and fish also cause a surge in Insulin levels after the meal without causing glucose levels to rise, a phenomenon which is little known to nutritionists and doctors and rarely mentioned in nutrition textbooks!
But does the fact that animal protein increases the levels of growth-promoting hormones and, thus, the rate of growth of the child, mean that it speeds up the arrival of puberty? Researchers have now looked at this issue directly:
Two studies released in the last 6 months suggest that eating more animal protein indeed promotes early menarche. In the German Dortmund Nutritional and Anthropometric Longitudinally Designed Study, girls eating most animal protein (meat, dairy, eggs) at the age of 5 and 6 experienced menarche on average 0.6 years earlier. In the UK Avon Longitudinal Study of Parents and Children, girls eating most meat at the age of 7 had increased risk of early menarche (defined as occurring before 12 years of age) by 75 per cent, in comparison to girls eating least meat. At the same time, plant protein consumption was shown to delay puberty.
Furthermore it seems that eating animal protein will programme more than just the rate of growth and timing of puberty in your child. Numerous studies in young adults and children have shown total animal protein intake to be the only nutrient associated with higher BMI and an increased likelihood to become obese in later life. Whereas, plant protein intake has been shown to be protective against childhood obesity.
Plant Protein - Slow and steady wins the race
Observations of different populations around the world seem to be consistent with this influence of dairy and animal protein on the timing of puberty and body weight. The rapid rise of obesity and breast cancer in Asian countries has coincided with the change from traditional plant-based eating patterns to a more Western style diet, higher in fat and protein including meat and dairy products on a scale that was never consumed before in this region. Not for nothing is cancer known as Rich Mans disease.
At the same time, the age of puberty has fallen and the average height has increased. It is likely that this is caused by increases in IGF-1 and Insulin levels in these populations triggered by dietary changes. Indeed, IGF-1 and Insulin levels in the population with the lowest breast cancer incidence in the world, the Okinawans in Japan, are significantly lower than those seen in Western countries and this has been attributed to their traditional plant-based diet, with very little animal protein and almost no dairy consumption. Okinawans who maintain a traditional diet and lifestyle are shorter and experience delayed menarche.
A low fat, plant-based, high-fibre diet, has been shown in numerous studies to be the most effective intervention to reduce both Insulin and IGF-1 levels in people from Western countries Adult vegans tend to have lower IGF-1 concentrations than adult vegetarians and omnivores. Although some studies have shown that Western vegetarian girls enter puberty later than their omnivore friends of the same ethnicity, others did not confirm this finding. However, it should be noted that the Western vegetarian diet is significantly higher in animal protein from dairy products and eggs than the traditional diet followed in Asian countries like Japan, rural China, Korea, etc. with later age of menarche.
What can you do?
Although we do not have all the answers yet and more studies need to be conducted to provide clear recommendations, it seems prudent to decrease the amount of animal protein in your child’s diet and replace it with plant protein. (Ed: It should be noted that CANCERactive has covered many studies on the links between cows dairy consumption and increased cancer risks in men and women and we are firmly against the consumption of cows dairy for both young and old for the reasons presented and others).
NUTRIENTS TRADITIONAL BURGER CHICKPEA BURGER
Energy 300 kcal 300 kcal
% kcal fat 70 13.5
SFAg 4.62g (x9.5 more) 0.32g
Cholesterol 60 mg 0 mg
Fibre 0 15 g
Protein 13.8g 18 g
Zinc 2.49 mg 2.91 mg
Iron 1.5 5.28 mg
Folic Acid 9 mcg 318 mcg
Magnesium 21 mg 100 mg
Plant protein has numerous advantages that surpass its beneficial effects on puberty timing. It can decrease your bad (LDL) cholesterol and increase your good (HDL) cholesterol. For people suffering from hypertension, it can decrease blood pressure, independently from other dietary measures. Another advantage is that it does not acidify your body as much as animal protein and therefore does not lead to leaching of calcium from your bones in order to neutralise the acids. However whats most relevant for your child is that plant protein comes from foods with much higher nutrient density, i.e. concentration of nutrients per unit of energy. There are far higher levels of vitamins, minerals and protein (per 100kcal) in pulses than in meat or cheese. Beans, lentils and chickpeas contain almost no saturated fat and have no cholesterol, both of which promote the build-up of fatty plaques on artery walls (atherosclerosis), even in young children.
You might be surprised that consumers of meat, dairy and egg products derive most of their calories not from the protein, but from the fat content. So if you are thinking you are adding protein to your childs pasta by sprinkling it with cheese, be aware that 80 per cent of the energy you are providing your child will come from the fat!
Good sources of plant protein include beans, lentils, chickpeas, peas, tofu, as well as whole grains, seeds and green leafy vegetables. If you serve a variety of all those products throughout the day, you are providing your child with full quality protein, with all essential amino acids needed for growth and development. The theory of plant protein lacking essential amino acids or being of inferior quality is a myth, and currently the biggest health and nutrition organisations in the world including American Dietetic Association, World Health Organisation and Institute of Medicine Food and Nutrition Board in the US officially debunk it in their statements.
So treat your child to bean burgers, chickpea stews, lentil pates, hummus, and other plant-based delicacies at least 5 times a week. Does it provide your daughter with future guarantee for breast cancer protection? No it doesnt, although research is clear that it does reduce the risk. What it does guarantee is a better overall quality of the diet with higher nutrient density and, if you also reduce your childs animal dairy fat consumption (milk, butter and cream), protection from atherosclerotic plaques and thus cardiovascular disease.
FAT CONTENT (%KCAL)
Fruit:3-5% (avocado-70%) Meat: 30-80%
Vegetables: 3-12% Dairy:: 15-80%
Pulses: 3-5% Fish: 10-60%
Grains: 6-10% Oils: 100%
Sweets, processed foods
Nuts and seeds: 70-80% 40/70%
Gosia Desmond BSc Nut Med, MSc Diet, MBs, MA
Gosia is Research Director in Nutrition and a lecturer at The College of Naturopathic Medicine in the UK and in Ireland. She is also a nutritionist and a researcher at the Childrens Memorial Health Institute in Warsaw where she is currently conducting a study looking at the effects of current diet on children’s future health. She is actively campaigning for healthy school lunches in Poland with several charities in Poland. She is a guest lecturer at the Warsaw Medical University.
For further information about studying a range of natural therapies with the College of Naturopathic Medicine, please call 01342 410 505 or visit www.naturopathy-uk.com
(For further information about this article please contact Penny Thomson at CNM on the number above.)