How diet affects DNA through the generations
Professor Ricardo Uauy, Professor of Public Health Nutrition Institute at the Nutrition, University of Chile and London School of Hygiene and Tropical Medicine, delivered the annual lecture at the Royal College of Physicians, presenting the results of scientific studies across the world demonstrating how nutrition pre-conception and in the early years influences risk of ill health and chronic diseases across the life-course. In particular, he described how environmental factors, including a mother’s diet, can cause epigenetic changes (modifications to DNA that control whether a gene is turned on or off and how much of a particular protein is made) in the fetus. These epigenetic changes can be passed to children from the mother or the father, or from grandparents to grandchildren, causing them to persist across multiple generations.
Mothers’ diets and risks of childhood disease
Clear examples of mothers’ diets ‘programming’ their children’s risks of future ill health and economic productivity include neural tube defects linked with folate deficiency and altered mental development due to iodine deficiency. Worldwide, iodine deficiency affects about two billion people and is the leading preventable cause of impaired intellectual development. Iodine deficiency is also a potentially serious problem in the UK, particularly in teenage girls. In many countries, this has been cheaply addressed by adding small amounts of iodine to salt. Professor Uauy therefore urged consideration of the potential clash between the need to improve iodine status across the world and the need to reduce population intakes of salt to reduce risk of high blood pressure.
Poor maternal nutrition and ‘bone age’ in children
Inadequate maternal and early nutrition also influence bone age (a measure of the degree of skeletal maturity of a child) and there is good evidence of the connections between slow growth in height early in life and impaired health and educational and economic performance later in life. In developing countries, the World Bank estimates that a 1% loss in adult height due to childhood stunting is associated with a 1.4% loss in economic productivity. In contrast, exposure to maternal obesity or fast (catch-up) growth in early infancy can lead to central fat deposition and increased risk of obesity in later life.
The need for diet quality not quantity for reducing chronic disease
Professor Uauy explained that countries with the greatest prevalence of risk factors for chronic diseases such as high blood pressure, elevated blood cholesterol and physical inactivity are not developed countries where it is assumed that obesity is at its highest, but developing countries where undernutrition is also common. In these countries, poor nutrition is also often associated with obesity, as well as stunted height in the population, and Professor Uauy stressed that in these regions emphasis should be put on understanding the type of weight gain required, rather than making weight gain itself the sole objective. This emphasises the need to think about diet quality rather than just quantity of food or calories.
Professor Uauy said: “Nutrition needs to be fine-tuned accordingly so that the right nutrients are being obtained by women pre-conception and during pregnancy, and by their children in early life, to help them achieve weight gain without become overweight or obese, ensure adequate nutrient intakes, optimum bone growth and protect against stunting.”
A tribute to Prof David Barker
The BNF Annual Lecture is usually delivered by the winner of the previous year’s BNF Prize and Professor Uauy paid tribute to Professor David Barker, last year’s recipient, who sadly died in 2013 aged 75 years. Professor Barker’s daughter, Dr Mary Barker, had received the BNF Prize on behalf of her father, who was honoured with the Prize for his outstanding work in the area of intrauterine and early postnatal health, and his ‘Barker hypothesis’ or ‘fetal programming hypothesis’ which states that the environment of the fetus and infant determined by the mother’s nutrition and the baby’s exposure to infection after birth, determines the pathologies of later life.
Closing the Annual Lecture, Professor Judy Buttriss, Director General of the British Nutrition Foundation concluded: “The challenge for us in the UK is to improve nutrition in teenage girls and young women well ahead of pregnancy. This is the group we really need to work with to ensure a healthy body weight and improve the quality of their diets for future generations. But to achieve this we need leadership in up-skilling healthcare professionals in obesity prevention and weight loss support as well as general nutrition.”