Vitamins and Minerals

Specific vitamins, minerals and other nutrients:

Most vitamin and mineral supplements are of no benefit and some may be harmful. With few exceptions we recommend that you get your vitamins, minerals, fibre and other phytonutrients from minimally processed plant foods. The supplements that may be required are related to modern living conditions rather than any inherent deficiency of a plant based diet. Clean food and water and safe food handling, whilst preventing disease, may remove most of the bacteria-derived vitamin B12 from our food supply. Indoor living can deprive us of the UV rays that are required for vitamin D synthesis. Many people take supplements as an insurance policy against dietary inadequacy or to detoxify the effects of too many rich foods. Unfortunately, supplements neither emulate the benefits of nutrients from plants, nor detoxify the harmful effects of excess animal protein, fats and processed foods.

Whole food is complex (see ‘Whole’ by T Colin Campbell in resources below). Our understanding of it is very basic. We know which nutrients are absolutely essential for life and the approximate amounts required. We have identified only a small number of the thousands of other biologically active substances in plants (known as phytochemicals or phytonutrients). We know little of the interactions between these various nutrients and phytonutrients. Often a high intake of a particular nutrient from food is associated with a health benefit, such as less cancer, but when we give them as supplements rather than as whole foods the benefit may be absent or reversed, increasing cancer risk.

There are some medical conditions in which vitamin supplements can be used as a pharmaceutical. Several of the B group vitamins can assist in reducing high homocysteine levels and this has been shown to reduce the progression of the early stages of dementia (see VITACOG study). The dietary approach would be to remove the cause of the elevated homocysteine levels by reducing animal protein consumption. While on the topic of dementia, Dr Neal Barnard recommends a vitamin B12 supplement and advises against taking supplements that contain minerals such as iron, copper and zinc as high levels of these may damage the brain.

No particular food has exclusive ownership of any particular nutrient. You do not need dairy foods for calcium, red meat for iron or fish for omega 3 oils. You do not even need to know which foods are the “best” sources of any particular nutrient. You just need to eat enough calories of whole grains, legumes, vegetables and fruits to maintain a healthy weight. And if you wish to tweak your plant-based diet to include more omega-3s, iodine, resistant starch or any other nutrient or phytochemical then we suggest that you bypass the supplements and just find some whole plant foods rich in the particular phytonutrient and make them a regular part of your diet.

See video: Dr. John McDougall Medical Message: Vitamin Supplements


Peer-reviewed articles

Last updated 11 April 2015