In this section I’ll try to list the health effects of various nutrients in simple and, hopefully, fairly accurate sentences. Evidence for claims can hopefully be found in highlighted sections.
Vitamin C – Although vitamin C is believed by many to be a potent preventer of heart disease and there is good evidence that typical vitamin C supplements offer no such benefits.
Calcium – Sufficient calcium (often at least 640 mg a day according to studies by the FAO and WHO) is important for bone health and getting calcium from dairy may be better for bone health than calcium from supplements. However studies on older women taking calcium supplements have suggested large amounts of calcium (about 2grams/day) may increase heart attack and stroke risk and too much calcium may even worsen bone health.
Fish oil (long chain omega-3’s) – In heart attack survivors fish oil appears to reduce the risk of future heart attacks.
Linoleic acid (omega-6) – Although linoleic acid, a fat found abundantly in most vegetable oils, is often recommended as a heart healthy replacement for saturated fats there is little evidence this dietary change will reduce cardiovascular disease risk. There is also reason to suspect linoleic acid will increase cancer risk.
Monounsaturated fat – Monounsaturated fatty acids, or MUFA, appears to be healthier than the predominant dietary polyunsaturated fat linoleic acid on various metrics. MUFA may be slightly healthier than saturated fat based on a few studies, but the evidence is weak and no long term trials have confirmed this.
Salt/Sodium – More than 5–7.5 grams of salt daily (or 2-3 grams sodium), may promote heart disease, but inadequate salt (possibly below 5 grams, or 2 grams of salt) also appears to be a significant health risk.
Sugar – Sugar, in the form of sucrose, appears unlikely to directly cause diabetes unless consumed in very large quantities (I.E. over 100-200 grams a day). However, because refined sugar lacks nutrients and often causes overconsumption it may contribute to diabetes risk by inducing malnutrition or weight gain. Because it likely prevents these negative effects fruit is likely the healthiest source of sugar, although honey also appears better than refined sugar.