How do I know which manufacturers of dietary supplements are reputable?

Find out from the company you are purchasing product from where their product is made. Do they manufacture themselves or is the product contract manufactured and packed off by themselves. Speak to the person in charge of quality control procedures. Find out their qualifications and find out to what lengths the company goes to ensure the quality of their products. How much is spent and how many people are employed to carry out quality control procedures. Find out what back up services this company provides. Are there experts available to advise you if you have problems. Are your questions dealt with promptly and thoroughly.

Most supplements are best taken straight after a meal. Because they are concentrated they should be mixed with food in your stomach. Herbs are best taken 20 minutes before a meal if taken to improve digestion or otherwise 20 minutes after meals.

Amino acids should be taken between meals for increased absorption.

Minerals such as Calcium and Magnesium, which have natural relaxing properties, are best taken with water or fruit juice on an empty stomach before bed.

If you require Calcium, Iron and Zinc, take all 3 at separate meals to avoid competition for absorption.

Do not take them all at once. Take them in divided doses up to 3 times daily to ensure a regular level is present in the blood.

RDA refers to 'Recommended Daily Allowance' and RDI 'Recommended Daily Intake'. The first RDA's were developed in the USA in 1941 by the Food and Nutrition Board of the National Academy of Sciences. The USA Government faced with entering World War II and anticipating food rationing and problems with food supplies to the armed forces, wanted to ensure proper nutrition within a limited availability of food, avoiding deficiency diseases such as scurvy, pellagra or beriberi.

RDA's are a broad guideline for measuring adequate national dietary intakes and the overall nutritional status of the whole population and vary from country to country. They should not be confused with individual requirements which have many variables such as those brought about by illness, e.g. arthritis, asthma, eczema, diabetes, heart disease, etc; vegetarians, vegans, medication users, heavy alcohol users, smokers, pregnant or breastfeeding, teenagers who have not completed their own growth process and those who have injuries or are overcoming surgery.

Although the use of RDA's have almost eliminated deficiency diseases such as scurvy, beriberi and pellagra, it is not a good measure of the health of the population as it does not take into account an individual's needs.

Vitamin and mineral deficiencies adversely affect our health. Initially, the deficiency reduces our tissue stores leading to reduced enzyme activity and causing abnormal metabolism as vitamins and minerals are essential for enzyme activation. As the deficiency progresses there can be unspecific changes occurring such as reduced immunity, fatigue, or changes in behaviour such as irritability or depressed feelings. Ultimately classical deficiency signs and symptoms occur such as broken blood capillaries, easy bruising, bleeding gums (Vitamin C) and if deficiency continues physiological changes resulting in death can occur, as occurred in scurvy. Today it is rare to see cases of scurvy because most people get some Vitamin C in their diet. However, it is not uncommon to see clinical signs occurring as a result of insufficient Vitamin C as caused by reduced dietary intake of fresh fruit and vegetables or as a result of increased need for Vitamin C caused by smoking or medications such as Prednisone. Not only do our food choices affect our nutrient intake, but also agricultural methods, food storage, processing and meal preparation.

Our lifestyle choices e.g. smoking, alcohol or endurance sports as well as the presence of any health condition or regular use of medication, e.g. contraceptive pill, affect our particular need for specific vitamins and minerals.

Supplements provide vitamins and minerals normally found in food. Some medications increase the need for specific nutrients, particularly Vitamin C, folic acid or B Complex and liver supporting herbs such as Milk Thistle. There are occasions, however, when supplements interfere with some medications e.g. taking calcium, magnesium, iron or other minerals with the antibiotic tetracycline. You should also avoid nutrients or herbs that have blood thinning effects such as Vitamin E, Omega 3, Co Enzyme Q10, Horse chestnut, Sweet clover (mellilotus), Ginkgo biloba and high dose Garlic or Ginger, if taking anticoagulants such as warfarin.

Adverse drug-nutrient interactions are actually quite rare and the over-whelming majority of interactions are positive. Drugs like sulfasalazine used to treat colitis or rheumatoid arthritis deplete folic acid. Aspirin depletes Vitamin C and folic acid, diuretics deplete minerals and the contraceptive pill depletes the B Complex vitamins and a range of minerals. The list is extensive so finding a doctor who can give you advice on both conventional and nutritional medicine, or seeing a naturopath or checking with your pharmacist that what you are taking wont interfere with your medication is advisable. If none of these options are helpful contact the company whose products you are taking and request the appropriate information.

Vitamin A, D and Selenium taken in excess are the most likely to cause toxicity. When combining products ensure you (adults) do not take more than the following on a daily basis:

Vitamin A (retinol) 3000mcg (10,000 iu) Vitamin D 25mcg (1,000 iu) Selenium 200mcg (the limit per tablet in NZ is 150mcg, however there is no evidence of toxicity at 200mcg daily or less per adult dose)

We also recommend you do not exceed the following on a daily basis: Copper 5mg Iron 24mg (unless anaemic or low iron stores) Zinc 15mg

It is advised that men should not take iron tablets unless diagnosed by a blood test to be low in iron. Vitamin A supplementation during pregnancy should not exceed 2500iu, as high dose Vitamin A has been shown to cause foetal abnormality.

Tablets can be crushed and capsules can be cut, the contents squeezed out and blended with fruit juice and fruit if you have difficulty swallowing supplements.

Dietary supplements are best taken just after a meal with either water or fruit juice.

It has long been thought that dietary supplements are not needed by people who eat varied diets. However, in the past 10 years there is increasing nutritional research showing the potential benefits of nutrients above the RDA's in reducing the risk of diseases not recognised as classic deficiency diseases, e.g.

Calcium 1000mg-2000mg: Slows the decline of bone density reducing the risk of osteoporosis [1]. [Calcium RDA is 800mg]

Folic Acid 400mcg+: Before conception and in early pregnancy decreases the risk of baby developing neural tube defects, e.g. spina bifida.[1]

Vitamin E 400iu daily or greater, significantly decreased low density lipoprotein (LDL) cholesterol oxidation in blood compared with 200iu or less of Vitamin E which showed no such effects.[1]

Vitamin E 400iu-800iu daily showed a significant decrease of non fatal heart attacks in people who were at high risk.[1]
[Vitamin E RDA is 10iu]

Selenium 200mcg daily significantly decreased total incidence and lung cancer deaths and total colorectal and prostate cancer incidence. [1]
[USA RDA is 70mcg. No NZ RDI has been established]

[1] Vitamins and Minerals: efficacy and safety - John N Hathcock. American Journal of Clinical Nutrition. 1997:66:427-37

The length of time you will require dietary supplementation depends on the reason you are taking them, e.g. if your diet is deficient in iron, you will require iron supplementation until your blood tests are normal. After which time if you have increased your intake of iron containing foods, ongoing supplementation won't be necessary.

However, if you are on medication that effects nutrient levels or you have a specific health problem, ongoing supplementation maybe beneficial. If you have any doubts about what you are taking, we suggest you consult a naturopath or contact the company whose products you are taking.

This is due to the presence of the B-Complex Vitamin riboflavin. It is a sign that your body is absorbing the B vitamins well and that any excess to your needs is passing out in your urine.