Page 3 2012 Vol 1
Nutritional supplements explained
A trip down the nutrition and supplement aisle of the supermarket can be baffling. Vitamins, minerals, food supplements.....they all claim to help. But do you really need them? Which ones? And how much? Dietitian Terrill Bruere says our need for various minerals and nutrients depends on our usual diet, life stage and overall health.
“Generally, food will give you all the vitamins and minerals you need unless you’re in a high risk group, for example vegetarians and women who are pregnant or breastfeeding,” she says. “Research has shown that some vitamin and mineral supplements have clear benefits, while for others, like glucosamine, research is inconclusive.”
Most of the supplements that people take are probably unnecessary if their diet contains a wide variety of healthy foods. They certainly don’t taste as good as fresh food and don’t give you all the other added benefits such as fibre, water, energy and protein that are just as important.
Omega-3 is a type of essential fatty acid or polyunsaturated fat found in salmon, tuna, flaxseed, linseed, walnuts and seaweed. It plays a vital role in brain function, growth and development. The Heart Foundation recommends adults consume about 500mg of marine source omega-3 every day to reduce our risk of heart disease. This is the equivalent of eating two to three 150g serves of oily fish every week. “Most people who eat fish, nuts and green leafy vegetables are able to get enough omega-3 from food,” Terrill says. However, some people, for example those with heart disease, may be recommended to consume higher levels, so their intake may need to be boosted with fish oil supplements (capsules or oil) and omega-3 enriched foods and drinks.
Naturopath Sandra Villella stresses that the type, quality and strength of omega-3 is important when choosing which fish oils to use. “There are two main types of omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and they each have a specific role and different therapeutic benefits.” Apart from lowering heart disease risk, research suggests that omega-3 may help reduce inflammation and support the immune system, reduce blood pressure and play a role in preventing and treating depression. The amount and type to have should be prescribed by a qualified health practitioner.
Calcium is vital for healthy teeth and bones. It also plays an important part in the health and functioning of nerves and muscle tissue. Good sources include dairy foods (preferably low-fat varieties) and calcium fortified products such as soy milk and breakfast cereals. Calcium is also found in leafy green vegetables (broccoli, cabbage family, bok choy, spinach), soy, tofu, canned fish with bones, almonds and unhulled sesame seeds. According to the Australian Nutrition Survey, about 90% of women do not achieve the Recommended Dietary Intake (RDI) for calcium. “The RDI in Australia is 1000mg for men and premenopausal women and 1300mg for postmenopausal women,” Terrill says. Women lose more calcium from their bones around the age of menopause however a diet high in calcium can slow down the process. “Women who don’t eat enough to reach the RDI or who dislike dairy foods may need to supplement,” Terrill says. ”However, it’s a common problem for women to forget or stop taking calcium, so if possible try increasing food sources first.” Discuss calcium with your GP if in doubt and don’t forget to check your vitamin D at the same time as this works with calcium to keep bones healthy.
Iron is involved in various body functions including the transport of oxygen in the blood and the immune system. ‘Haem’ iron is found in animal foods such as beef, chicken, fish and eggs – offal is a rich source. Non-haem iron is found in plant foods such as beans, lentils and green leafy vegies but is not as well absorbed by our bodies as haem iron. The presence of vitamin C or animal protein enhances the availability of iron derived from plant foods, so it’s good to add lemon juice, tomato or capsicum to your meals to boost iron uptake. Other sources include fortified breakfast cereals and drinks (e.g. milo), flours and grains. The Australian RDI for iron is 18mg for women 19-50 years and 8mg for women aged 51 years plus.“Iron is often low in women,” Sandra says. “It’s a balancing act of correct intake and maintenance of desired levels. Poor iron intake or an increase in blood loss, for example from heavy periods, may result in iron deficiency. It’s important to have a blood test before taking iron supplements to look at both haemoglobin and ferritin (iron store) levels.” Iron supplements are most effective when taken separately from calcium.
Folate assists the formation of red blood cells which carry oxygen around the body. It’s also needed for DNA synthesis and cell growth. Folate helps the development of the foetal nervous system and has been shown to reduce the risk of neural tube defects such as spina bifida in babies. “Women planning pregnancy need a folate-rich diet and should also take a folate supplement providing 400μg/day folate for one month before and three months after conception,” Terrill says. Good sources include raw green leafy vegetables, legumes, seeds, liver, poultry, eggs, fortified cereals and citrus fruits. Because of the importance of folate, all flour used in bread making (except for flour to be used in breads listed as ‘organic’) is now fortified with folic acid (the synthetic form of folate).
Vitamin B12 is involved in the production and maintenance of nerve cells, mental ability, red blood cell formation and energy production. Vitamin B12 and folate depend on each other to work properly. Vitamin B12 is naturally found in animal products – good sources include fish, poultry, liver, meat, milk, cheese and eggs. Vitamin B12 is generally not present in plant foods, but fortified breakfast cereals are a readily available source. Deficiency is most common in elderly people, vegans and breastfed babies of vegan mothers and is easily detected by a simple blood test. Vitamin B12 supplements are usually given as an under the tongue supplement. Some people may lose the ability to absorb vitamin B12 or have such low levels they need injections.
Zinc is found mostly in animal products. It stimulates enzyme activity, supports a healthy immune system, helps synthesize DNA, is essential for wound healing and supports the healthy growth and development of the body during adolescence, childhood and pregnancy. Teenagers, vegetarians and vegans are most at risk of zinc deficiency. Taking zinc supplements at the first sign of a cold can reduce the virus’ duration by about a day. Zinc reduces the replication of the cold virus and helps to boost the immune system. However, zinc supplements are not recommended for general cold prevention (unless prescribed), as too much zinc can interfere with the absorption of other nutrients like copper and iron. Zinc from your diet is the best source – good sources include oysters, seafood, meat, sardines, sprouting grains and breads baked with yeast. Most people will get enough zinc if they are eating the foods that meet their iron and calcium needs.
Myths about supplements
1. A multi-vitamin will compensate if you don’t eat enough fruit and vegetables. FALSE.
“Remember, supplements do just that,” Sandra explains. “They can fill ‘gaps’ in dietary intake but don’t replace food. After all, food is more than its parts. If you were to cut out fruit and vegetables, you would miss fibre, other vitamins and minerals, antioxidants, natural colours and of course...flavour!”
2. There are no risks in taking over-the-counter nutritional supplements. FALSE.
“Just because vitamins and minerals are natural doesn’t mean that everyone is an expert,” warns Sandra. “Many supplements need to be prescribed by a practitioner trained in their use. Some can also interfere with other medications.” Supplements may also interact with each other and put other nutrients at risk by affecting food absorption. See a trained health practitioner for appropriate diagnosis and advice.
3. The nutrients in supplements and pills are more potent and effective in the body than those found in foods. FALSE.
With the exception of folate and some vitamins that are taken as a therapeutic intervention, absorption is often better from food than supplements.
4. ‘More is better’ when it comes to supplements. FALSE.
In fact, it can be dangerous. For example, too much iron can be toxic – especially for children. Too much calcium from supplements may cause problems like bloating and constipation. Too much omega-3 can interfere with blood thinning.
5. You can get enough vitamin B12 from eating mushrooms. FALSE.
B12 is only found in animal products.
6. If I’m tired I must be low in iron. FALSE.
Don’t assume that vague symptoms like fatigue are due to lack of iron. See your GP and have a blood test first to establish if it is low. Iron may be low because of a medical condition.
7. Iodine deficiency is a thing of the past. FALSE.
Terrill says the incidence of iodine deficiency is increasing and pregnant women in particular need extra iodine in their diet. The bread industry is now required to use iodised salt to help meet this need.
8. More expensive brands of multi-vitamins are better. FALSE.
Some may have more active ingredients or different compositions, but on the whole, Terrill says cheaper brands are likely to be just as good.
9. It’s okay to self-diagnose and treat vitamin deficiency, as long as you don’t exceed the recommended doses. FALSE.
Don’t believe all the marketing – if you have particular symptoms or concerns, see a GP or health practitioner trained in nutrition. Some nutrient deficiencies are detected via blood tests, but others are detected by clinical signs and symptoms. There is a big difference between taking supplements for therapeutic intervention and taking them to ‘fill-in’ dietary gaps. What’s more, you could be spending lots of money on pills that aren’t having any effect!
For more information
Dietitians Association of Australia
National Health and Medical Research Council Nutrient Reference Values
Content Updated February 2012