Depression is a major health problem, particularly for older women. According to the mental health trust, depression is the most common mental disorder in Britain. It affects one in five older people and recorded rates are one and a half to two times higher in women than in men.
Depression can be caused by a combination of biological, psychological, and social factors but did you know that your diet could have an impact? It has been suggested that mood disorders and depressive status may be accompanied by lowered zinc status in the body, and adequate consumption of zinc increases a general perceived well-being.
The link between dietary zinc and depression
There have been two recent studies which have demonstrated a relationship between dietary zinc and depression. In 2010, Amani and colleagues compared the dietary intake of zinc in female students with varying degrees of depression found that there was a significant correlation between low intakes and depression. They found that depressed individuals were eating lower servings of red meat and chicken, both good sources of zinc, than usual amounts eaten by their peers. Overall, serum zinc levels were shown to be inversely correlated to levels of depression.
In a new study published this month, researchers looked at the relationship between dietary zinc intake and depression in over 400 participants, and also showed an inverse relationship was shown between the two. The researchers concluded that long term zinc may modulate symptoms of depression
Are you at risk from zinc deficiency?
The most recent national diet and nutrition survey identified dietary zinc as one of the “at risk” minerals for older people and found that at least 8% of older people living in their own homes were deficient. Rates were even higher for those living in care or residential accommodation.
The required intake of zinc is about 4-7 mg a day for women. People who are at higher risk for zinc deficiency include vegetarians, those in poverty and with resultant poor dietary intake and those with gastrointestinal problems. Women who take calcium supplements after menopause may also risk zinc deficiency due to reduction of absorption. This may result in zinc requirements being slightly higher.
Most people should, however, be able to get their zinc requirements through diet alone. Supplements are generally not recommended as zinc toxicity, with symptoms of nausea, diahorrhea and vomiting can occur at levels over 50 mg. The department of health advises that if supplements are taken, that they be no more than 25 mg/day.
There have been some studies looking at supplementation of zinc and effect on mood in women. In 2010, Sawada and colleagues investigated the effects of giving women a multivitamin/mineral and a 7 mg zinc supplement for ten weeks. After ten week, the women taking the zinc were found to lower scores in terms of depression as well as anger and hostility. The researchers concluded that zinc supplementation may be effective in reducing depression and anger.
Before supplements are considered, dietary intakes should first be improved. Generally if foods containing zinc are at suboptimal levels, other nutrients will also be at risk.
Dietary Sources of Zinc
Zinc in foods is highest in protein containing foods such as meat, poultry, shellfish, (oysters and crab are good sources), milk and cheese. Legumes, seeds (like pumpkin seeds) and whole-grains do contain zinc but you would need fairly large quantities to reach dietary recommendations with these foods alone.
To give you an example of amounts of zinc in commonly used foods:
6 medium oysters, cooked 21.3 mg
1 8oz (226g) sirloin steak 13.8 mg
1 8oz rump steak, grilled 9.1 mg
1 medium portion beef mince 7.8 mg
120g pork loin chop 3.5 mg
2 rashers back bacon (50g) 1.2 mg
100g chicken, dark meat 2.2 mg
1 average slice ham (24g) 0.4 mg
100g tuna in brine, drained 0.7 mg
200ml glass s/skim milk 1.6 mg
40g cheddar cheese 0.4 mg
1 av portion scr egg (100g) 1.4 mg
Small can bk beans (250g) 2.1 mg
70g chick peas 0.4 mg
2 Tbsp Kidney beans 0.3 mg
Improving your intake of zinc
If you feel your zinc intake may be at risk and you may be at risk of subsequent depression, make sure you are getting enough meat, chicken and dairy foods in your daily diet. Many women reduce the amount of these foods in a misguided attempt to reduce weight but they should be included every day. For vegetarians, make sure dishes include wholegrain cereals, kidney beans and eggs and try to incorporate kidney beans and chickpeas into salads. Just making these dietary changes could improve your enjoyment of life.
Sawada T, et al. (2010) Effect of zinc supplementation on mood states in young women: a pilot study. Eur J Clin Nutr 64(3):331-3
Hoare J. (2004) National Diet & Nutrition Survey: adults aged 19-64 years
Yary, T., Aazami, S.(2011). Dietary Intake of Zinc was inversely associated with depression. Bio Trace Elem Res. Sep 20
Amani, R. et al.(2010) Correlation between dietary zinc intakes and its serum levels with depression scales in young female students. Biol TraceElem. Nov; 137(2):150-8.
Photo credit: Tina Phillips