Dietary Antioxidants & CVD (Edexcel International A Level Biology)

• We know that eating fruits and vegetables is good for us; one reason that has been proposed to explain this is that these foods are high in chemicals called antioxidants
  • Antioxidants include vitamins such as
    • Vitamin A; found in orange vegetables such as carrots and sweet potato
    • Vitamin C; found in citrus fruits
    • Vitamin E; found in leafy vegetables, some nuts, and some oils
• Some research into antioxidants has been held up in support of the theory that antioxidants in the diet reduce the risk of heart disease, but more recent data analysis has suggested that there is not enough evidence to conclude this
  • Some recent research even suggests that antioxidants could increase the risk of heart disease

The evidence for antioxidants

• We know that vitamin C is important for the formation of connective tissues in the body, so it is logical to think that an increase in dietary vitamin C could help to reduce the damage to the artery endothelial layer that leads to atherosclerosis
  • Atherosclerosis is the process by which fatty plaques called atheromas develop inside a damaged arterial lining
• In a study involving 1 605 men in Finland, 70 men had a heart attack between 1984 and 1992
  • 13.2 % of the men with low vitamin C levels had a heart attack
  • 3.8 % of the men with normal vitamin C levels had a heart attack
• Many concluded from this study that increasing vitamin C intake would reduce the risk of heart disease

Inconclusive evidence

• A large analysis of many studies on vitamin C and heart disease was carried out in 2016
  • A study that analyses the results of many existing studies is known as a meta-analysis
• The 2016 study showed that there was no clear relationship between increased vitamin C intake and a reduced risk of heart disease
• The study also suggested that taking antioxidant supplements could be harmful to circulatory system health
• This is an example of an area of study with conflicting evidence; it is essential that all evidence is taken into account when drawing conclusions or deciding that evidence is still inconclusive