Many nutritionists believe that a balanced and varied diet should supply all the vitamins and minerals that the body needs for good health. Others, however, argue that food supplements provide a sensible form of health insurance because many people do not eat enough fresh foods, and because modern food processing techniques and overcooking can destroy precious nutrients.
Food supplements are available in many different forms, including various vitamin and mineral combinations and alternative plant extracts. Whereas nutritionists disagree about whether we all need to take supplements, most accept that there are certain groups of people who may need them.
DEFINING FOOD SUPPLEMENTS
The term ‘food supplements’ refers to the commercially produced pills, capsules, powders and liquids that contain vitamins, minerals and other substances. There is a vast array of supplements on the market. The range includes the various single and combination vitamin and mineral supplements, as well as alternative supplements, many of which are based on plant extracts.
Supplements may contain other ingredients added in the manufacturing process. These include fillers, binders, lubricants and coatings. Some of these added ingredients, such as cellulose (plant fibre), make the supplement more nutritious; other additives make it less nutritious or even conflict with dietary requirements; for example, pills made with animal-based lubricants are inappropriate for vegans. Nutritionists can advise about supplement quality and recommend specific brands.
THE SUPPLEMENTS DEBATE
Views on the necessity of supplements are divided. The conventional wisdom is that a well-balanced diet provides a far more complex blend of nutrients – as well as active substances with protective properties – than pills ever can. But there are some nutritionists who argue that there are so many nutrient depleters in industrialized society (air pollution, alcohol and artificial additives in food, for example) that even the healthiest diet cannot deliver enough nutrients to keep people healthy. There is also an increasing trend for people to seek ‘optimum nutrition’ – taking supplements as a preventative medicine to promote longevity and prevent degenerative diseases such as heart disease and cancer.
Although there is much debate about supplements, and views often differ from one country to the next, there is consensus on one aspect of the debate: that certain groups of people, for example, smokers, elderly people and women planning a pregnancy, can benefit from them. Throughout a person’s life there are factors that can either increase the need for certain nutrients or reduce the body’s ability to absorb them. Stress, alcohol and some medication, for example, can impair the body’s ability to absorb nutrients.
VITAMIN AND MINERAL SUPPLEMENTS
The range of supplements includes single-vitamin and single-mineral supplements, multivitamin supplements, multi-mineral supplements and combined multivitamin and mineral supplements. Some vitamin supplements combine several vitamins that complement each other or that have the same purpose. For example, an antioxidant supplement may combine the antioxidant vitamins C, E and betacarotene. This combination is thought to effectively fight free radicals.
In general, multiple-nutrient supplements are preferable to single-nutrient supplements. It is important to be aware that taking a single-nutrient supplement can interfere with the delicate balance of nutrients in the body, especially if the dosage is very high. Too much of one nutrient can interfere with the body’s ability to use other nutrients – anyone considering taking megadose supplements should seek expert advice.
Taking a single-nutrient supplement incorrectly also puts people at risk of overdose. Taking too much vitamin A in its animal form (retinol), for example, can cause drowsiness, hair loss, headaches and vomiting, as well as liver and bone damage. Pregnant women are advised not to take supplements containing high doses of vitamin A because overdosing can cause a risk of birth defects in newborn babies. Vitamin A from plants (betacarotene) is not toxic, but an excess of betacarotene can turn the skin yellow.
Vitamin D is another vitamin that can cause toxic reactions in large quantities. Because it encourages calcium absorption, an excessive intake can cause a build-up of calcium deposits in the blood, leading to irreversible damage in soft tissues such as the heart, lungs and kidneys.
People who are allergic to milk and yeast should avoid supplements that contain lactose (milk sugar) or yeast. Some supplements contain sugar, to sweeten the taste, in the form of glucose, fructose or dextrose – although these are not harmful, sugar-free alternatives are preferable.
Since every person has different needs regarding supplementation, it is advisable to seek the advice of a nutritionist. However, there is probably minimal danger in supplementing vitamin C and essential fats.