Nutritional Supplement

Written by: Sajedeh Ghasemi

Published on: March 6th, 2018

Vitamins and minerals cannot usually be synthesized in the body but occur naturally in certain foods. They are essential in small quantities for normal body metabolism, functioning as cofactors within enzyme systems required for the normal function of life.

If steady intakes are not met, deficiency diseases occur, which can sometimes lead to death. However, excess intake can result in toxicities, even at doses which were generally appeared to be safe. Most individuals in North America ingest sufficient vitamins and minerals in their diets to prevent deficiency diseases. Insufficient vitamin D levels may be common in Canadians due to the northern climate since it is derived primarily from exposure to sunlight.

Although preliminary studies may suggest that nutrient supplement prevents or reduces risk of chronic disease, a benefit is yet to be proven by large human trials in most cases. Additionally, long-term nutrient supplement may be harmful.

Chronic intake of some drugs can affect or interact with vitamins and minerals. Depending on the nature of interaction, it may be necessary to avoid combination therapy, or drug therapy may impose use of supplements.1

The goals of using supplements are based on below factors:

  • Identify and correct any recognized nutritional deficiencies;
  • Tailor supplement to individual and specific diets;
  • Ensure excess is not consumed and limit antioxidant supplements;
  • Ensure no significant drug-nutrient interactions;
  • Assess benefit versus risk in individual patients for prevention or treatment of disease; and
  • Treatment of a disease or condition with micronutrient supplementation should be supported by good evidence and monitored for adverse events.

In this continual articles I am going to cast light on the nutritional supplement in detail and guide the readers how to meet their requirements.

Dietary Reference Intakes

The Dietary Reference Intakes (DRIs) are a comprehensive set of nutrient reference values for healthy populations that can be used for assessing and planning diets. This reference table is established cooperatively by Canada and the United States and are derived from scientific data. It provides a range of values from optimal to maximum based on indicators of good health, prevention of chronic disease and evaluation of the possible adverse effects of excess intake.2

Selected DRIs for common nutrients are presented in Table 1.

Indications for General Preventive Supplementation

A significant benefit from micronutrient supplement is unlikely for most of the general adult population.3 Therefore, consumption of whole foods such as fruits, vegetables, whole grains, legumes, nuts, and fish, as these may contain other important nutrients, are required for optimal health and have been shown to decrease the risk of chronic disease and overall mortality. The benefit on overall mortality effect of supplement with specific nutrients (e.g., vitamin D and omega-3 fatty acids/fish oils) are in waiting for further evidence from randomized and controlled trials. Most Canadians have adequate intake of micronutrients although deficiencies in vitamins A, C, D, calcium, magnesium, zinc, and folate have been identified in high-risk groups (e.g., those at the lowest level of income and/or educational attainment).4

Certain groups of individuals may require specific preventive supplements.

Populations with increased requirements:

  • multivitaminwith folic acid (0.4–1 mg/day; 5 mg/day preconception if at high risk)
  • Pregnancy and breastfeeding
  • calcium(intake from dietary sources recommended but many people do not ingest enough): age 14–18 years = 1300 mg/day; age 19+ = 1000 mg/day
  • vitamin D: consider 2000 IU/day for pregnant women during winter months
  • ironsupplement, if required (total = 27 mg/day). Routine iron supplementation during pregnancy in non- anemic women (hemoglobin >130 g/L) may not be without adverse effects and 16 mg/day total supplement is roposed.5 Intermittent iron supplementation (± folic acid) may be an alternative for preventing gestational anemia in non-anemic women with adequate antenatal care. Intermittent supplement is less likely results in adverse events such as nausea and GI disturbances compared with a daily regimen and results in similar maternal and infant outcomes. Additionally, the risk of high hemoglobin concentrations may be reduced. The most commonly used intermittent dosing schedule is 120 mg total weekly elemental iron, given on 1 day of the week in two equal doses. This regimen is not recommended for women who are anemic at the start of their pregnancy.

Populations at risk of inadequate intake:

  • Very low-calorie diet (<800 kcal/day), either voluntary or involuntary (overall insufficient intake)
  • Exclusion diets—lack intake of certain foods, e.g., whole grains, deeply colored vegetables and fruits, fortified cereals, animal-source foods:
    • vegan diets: vitamin B12, vitamin D, calcium and omega-3 fatty acids (from microalgae), iron, zinc
    • lacto-ovo-vegetarians: vitamin B12, zinc
  • Chronic substance abuse: vitamin C, vitamin B1, folic acid, vitamin B6 and vitamin B2 (riboflavin) in particular for alcohol abuse1
  • At-risk elderly (possibly due to polypharmacy, poor oral health, functional limitations, depression, dementia, social isolation): Vitamin B12 deficiency (primarily due to chronic food-cobalamin malabsorption and to a lesser extent pernicious anemia) and vitamin D deficiency are common in this group and may require supplementation
    • routine vitamin and mineral supplementation may be associated with increased mortality in elderly women, particularly supplemental iron. Supplementation is not associated with a decreased risk of infections in elderly persons living at home. 6

When you want to provide a supplement always check with your healthcare professional whether or not it is good for you, the below table shows the Daily dietary reference intake for vitamins and selected minerals.

Canadian Pharmacists Association. E therapeutic choices. [Internet]. Ottawa: The Association; 2016. Nutritional supplement; [revised 2015 February; cited 2017 January 6]; [about 14 screens]. Available from: with authorized username and password.Health Canada. Dietary reference intakes tables. Available – from: Accessed March 23, 2011.

McCormick DB. Vitamin/mineral supplements: of questionable benefit for the general population. Nutr Rev 2010;68(4):207-13.

Tarasuk V, Fitzpatrick S, Ward H. Nutrition inequities in Canada. Appl Physiol Nutr Metab 2010;35(2):172-9.

Cockell KA, Miller DC, Lowell H. Application of the Dietary Reference Intakes in developing a recommendation for pregnancy iron supplements in Canada. Am J Clin Nutr 2009;90(4):1023-8.

Andres E, Loukili NH, Noel E et al. Vitamin B12 (cobalamin) deficiency in elderly patients. CMAJ 2004;171(3):251-9.


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