An Insight into British ‘Mid-Life’ Micronutrient Intakes.
What are micronutrients and why they are an important part of nutrition?
Micronutrients are substances such as vitamins or minerals that are required by the human body in miniscule amounts. They help the body to produce enzymes and hormones needed for growth and development. Healthy eating habits, providing key dietary components alongside physical activity across mid-life, can help to maintain health and reduce or prevent age-related chronic diseases.
Today, around two billion people worldwide have micronutrient inadequacies. In the developed world, such as the United Kingdom, United States and Germany nutrient-poor food is abundant and consumed on a regular basis.
The consequences of micronutrient shortfalls can be severe with vitamin A, iron and iodine being of particular significant importance in terms of global public health.
Micronutrient intake also has implications to gut microbiota. Acute vitamin A deficiency can impact on bacterial community structure with Bacteroides vulgatus increasing in abundance in the absence of vitamin A.
Micronutrients such as iron, zinc and magnesium are positively associated with sleep duration with potential mechanisms appearing to involve the effects that micronutrients have on neurotransmitters and the expression of circadian genes.
Who needs to improve their micronutrient intake?
Micronutrient shortfalls are evident across mid-life in UK adults. These shortfalls are more prominent amongst females and young adults in their twenties. Mid-life should be the time to lay the foundations of good health in preparation for later life, however, current gaps exist between micronutrient intake and the actual recommended requirements.
Micronutrient intake in early adulthood is particularly important as these are typically the years of conception and childbearing. Nutritional intake in mid-life can help to future-proof health against debilitating and chronic diseases that can occur in later life. The physiologic aspects of age-related cognitive decline can begin as young as 18 years with healthy educated adults in their twenties and thirties also showing signs of deterioration.
A healthy and balanced diet is of utmost importance, however, the value of multivitamin and mineral supplements and food fortification strategies should not be overlooked in the context of today’s modern lifestyles. Did you know that in the UK there is a Government health message to supplement with 10 μg vitamin D between Autumn and Spring to protect bone and muscle health?
What we need to look out for
Improving diet quality through mid-life may help to protect health, prevent chronic disease, and disability and enhance economic productivity. Alongside this, fortification and supplementation strategies can help us achieve our dietary targets at this life-stage when we should be at our nutritional prime.
In the fight against obesity and subsequent obesity-induced diseases, we are now encouraged to reduce our food intake, it is important, however, to ensure that the micronutrient profile of our diet is sustained.
Is social media influencing our eating habits? A recent survey of social media tweets typically used by young adults found that 67.2% related to body image, eating disorders, fitness, food or dieting. This can have wider ramifications impacting on dietary habits and micronutrient profiles of young adults.
Ongoing dietary trends leading to the elimination or substitution of key food groups, can also impact dietary micronutrient levels.
Unfortunately, young women are at particular risk of micronutrient shortfalls. The consumption of eggs, milk and dairy correlates strongly against female nutritional iodine status. UK females having diets lower in red meat (<40 g daily) have reduced micronutrient intakes, especially zinc and vitamin D.
Veganism has also been found to impact on vitamin D, calcium, and vitamin B12, iodine and selenium intakes.
Meal frequency has also been positively associated with diet quality and micronutrient intakes, indicating that skipping meals or snacking rather than eating main meals may also impact on micronutrient intakes.
Where can we improve our micronutrient intake?
Sizeable gaps were found for magnesium intake compared with intake targets in males and females aged 20–59 years. Magnesium deficiencies could be a significant contributor to low-grade inflammation which typically underpins conditions such as diabetes, cardiovascular disease and hypertension. At a cellular level magnesium is thought to have a valuable role in the regulation of telomere function, integrity, and structure with telomere dysregulation being linked to aging and age-related disease such as cancer. Magnesium can be found in cashews, green vegetables, milk and sunflower seeds.
Amongst UK males, vitamin A shortfalls were apparent. The clinical importance of vitamin A is becoming increasingly clear with evidence of its role emerging in immune competence, tissue differentiation and the visual cycle. Men, aged 19-64 years, had an intake of fruit and vegetables slightly lower (3.9 portions daily) compared to women (4.1 portions daily). It has also been found that fruit and vegetable variety tends to be lower in men.
Amongst UK males, zinc shortfalls were apparent. Zinc is a known antioxidant with research showing that fertile males tend to have higher seminal zinc levels than their infertile counterparts. Zinc also has important catalytic, structural, and regulatory roles helping to support immunity and avert age-related diseases. Zinc shortfalls are somewhat surprising to see, especially amongst males given that meat and meat products are one of the main providers of zinc. It is possible that younger men in their twenties are eating less meat which could have contributed to lower zinc intakes in this age group. Zinc can be found in fortified cereals, nuts, poultry and red meat.
Selenium is an essential micronutrient associated with cancer, cardiovascular disease and autoimmune disease. Amongst UK women low whole-blood selenium levels have recently been linked to increased pre-eclampsia and pregnancy-induced hypertension risk. 40% of adults in their twenties had very low selenium intake. Selenium can be found in seafood and Brazil nuts.
Iron is an important micronutrient that ensures the development of normal red blood cells and healthy immune function Iron deficiency has also been associated with higher rates of depression in pregnancy. 33% of women aged 20–29 years had very low iron intake. Iron can be found in red meat and eggs.
Low fruit and vegetable intake may be one factor contributing to declining potassium levels. Potatoes alongside white vegetables are important dietary contributors of potassium. 24.7% had potassium intake below lower recommended nutrient thresholds. Potassium can be found in grains, legumes, meat and milk.
Derbyshire EJ (2018) Micronutrient Intakes of British Adults Across Mid-Life: A Secondary Analysis of the UK National Diet and Nutrition Survey. Frontiers in Nutrition, Clinical Nutrition Volume 5 | Article 55: 1-9.