When we think about influencing our health, we tend to think about what we are doing today, or what we might do tomorrow. But few of us think about nutrition in early childhood as having a big influence on our health as adults. Our Research Interpretation Manager, Isobel Bandurek, discusses five things to know about early life nutrition and cancer risk in later life.
1. How tall you are is related to your cancer risk
Yes, you read that right!
How tall you are as an adult might seem like an inert and inconsequential measurement: unchangeable. While it’s true that adult attained height is not something that individuals can do much about, to get to your adult attained height, your body will have gone through a process of growing. This process is affected by a host of factors – including genetics, epigenetics, childhood and adolescent growth rate, and age at puberty – and many of these are sensitive to nutritional factors. The hormonal and metabolic axes that influence adult attained height also influence many pathways related to cancer development.
This link is seen in our Continuous Update Project (CUP), where we found strong evidence that greater adult attained height is associated with increased risk of seven cancers, including colorectal and breast. Results of the analyses show an increase in risk ranging from five to 12 per cent per five-centimetre increase in height, depending on the cancer site.
So, ultimately, adult attained height is an imperfect but easily measurable marker of internal physiological processes that are linked to cancer development.
2. …and it’s the same for birthweight
There is also strong evidence from the CUP that greater birthweight increases the risk of premenopausal breast cancer – and the findings for birthweight are conceptually intertwined with the findings for adult attained height: birthweight is a marker of underlying physiological processes. The proposed mechanisms linking greater birthweight and increased risk of premenopausal breast cancer include long-term programming of hormonal systems, higher circulating maternal oestrogen levels, and raised IGF-1 activity.
3. The first 1,000 days are really important
The findings for adult attained height and birthweight underscore the importance of the first 1,000 days – from a woman’s pregnancy to a child’s second birthday. During this critical window, foundations of future health are laid down. This concept was first proposed by Barker in 1995 and is now more commonly known as the developmental origins of health and disease hypothesis.
Nutrition plays a particularly crucial role in these first 1,000 days. Providing the right nutrition – the right nutrients, in the right amounts, at the right time – to all infants is a heck of a challenge. However, part of the solution needs to involve promoting, protecting and supporting mothers to breastfeed.
4. …and supporting mothers to breastfeed is crucial
One of our Cancer Prevention Recommendations is for mothers to breastfeed their babies, if they can, while recognising that breastfeeding is not possible for all mothers, for a variety of reasons.
There is strong evidence from the CUP that breastfeeding protects against breast cancer in the mother and promotes healthy growth in the infant. This aligns with the World Health Organization Global Strategy for Infant and Young Child Feeding that recommends babies should be exclusively breastfed for the first six months of life, then for up to two years (or beyond) alongside other appropriate foods and drinks.
In most countries, only a minority of mothers exclusively breastfeed their babies until four months, and an even smaller number until six months. A comprehensive package of policies is needed to promote, protect and support breastfeeding, including making all hospitals supportive of breastfeeding, providing counselling in healthcare settings, implementing maternity protection in the workplace, and regulating the marketing of breastmilk substitutes.
5. We still need to work out the nuts and bolts of what’s going on across the whole life span
Nutrition is key in determining patterns of growth from conception onwards. However, the precise way nutrition influences growth and development, and its relation to later cancer risk, remain to be determined. That is why the CUP Expert Panel identified "better understanding of the impact of diet, nutrition and physical activity throughout the life course on cancer risk" as one of their six future research directions for the research community.
Furthermore, one of the workstreams of the CUP Transition is life course and cancer risk, and how that can be best investigated via the CUP in the future. I am thrilled to be working on this topic as the CUP Secretariat lead and look forward to updating you on our progress going forward!