Magnesium is found in fibre-rich foods such as green leafy vegetables, avocados, bananas, wholemeal bread and brown rice as well as in fish and meat. Excess magnesium exposure can cause breathing problems, skin and eye irritation, flu-like symptoms and an upset stomach. Low magnesium can cause muscle aches and pains, fatigue, osteoporosis, an irregular heartbeat and high blood pressure. Low magnesium is associated with heart disease, artherosclerosis, stroke and diabetes.