Tag Archives: Vitamin supplements

Calcium

You do not need to drink milk to get enough calcium. You will not make your bones stronger by drinking milk.

If you don’t believe these statements, don’t worry, you are not alone. Seventy years of marketing has convinced most health professionals that dairy foods, or a high-calcium substitute, are essential for human health. This is a rather narrow nutritional view when one considers that cow’s milk is only consumed by a minority of the world’s population, and for a relatively short period of human history. Most of the world’s population, including the majority of those of Asian or African descent, are lactose intolerant and suffer abdominal pain and diarrhoea if they drink milk.

While it is true that dairy foods are rich in calcium and that calcium is an essential nutrient for bone health, increased dairy consumption is not associated with stronger bones. In fact, a large Swedish study (Michaelsson et al 2014) found that higher milk consumption was associated with a higher rate of hip fractures (as well as a higher mortality rate). The higher prevalence of osteoporosis in countries that consume more dairy foods suggests that dairy products are not an effective preventative strategy.

You don’t need to reach for calcium fortified foods to get enough calcium on a whole foods plant-based diet

Like other minerals, calcium comes from the ground. Plants absorb it and animals in turn eat plants. Cows get their calcium from the grass. We can obtain all our calcium needs from whole plant foods, many of which have moderately high calcium levels. Some vegetables have a higher “nutrient density” for calcium than dairy foods (see Nutrient Density page). Interestingly, calcium is better absorbed from vegetables than milk, over 50% vs 32%. Many whole plant foods are rich in calcium – a cup of chopped kale, for example, provides as much absorbable calcium as a cup of milk.

Calcium content of food

Dairy (and ‘dairy alternatives’) has its own food group in the Australian Dietary Guidelines but this is no longer the case for the Canadian dietary guidelines. A liberal interpretation of ‘dairy alternatives’ might include beans, greens and other high calcium whole plant foods. A plant-based ‘milk’ with a similar calcium content to cow’s milk is not necessary. Indeed, it has been argued that a more appropriate comparator for plant ‘milks’ is human breast milk which has only a third of the calcium content of cow’s milk.

The recommended daily intake for calcium in Australia is extraordinarily high, up to 1300mg per day, a level which few people reach. It remains to be seen whether this will be revised in future guidelines given the evidence that high dietary calcium intakes are not protective against osteoporosis (Bolland et al 2015). The World Health Organization (2004) notes that calcium needs are increased by high intakes of animal protein and sodium. Dietary animal protein increases urinary loss of calcium and at very high protein intakes it can be difficult to absorb enough calcium to offset losses. WHO suggests a lower calcium requirement where animal protein intake is lower, and if sodium intakes were also lower as in developing countries then the calcium requirement would be even lower, e.g. 450mg (WHO 2004, p. 82).

A study of older Chinese men and women on a “plant-based diet” in the Journal of Bone and Mineral Research (Fang et al. 2016) suggested there was an optimal range for calcium intake, and that both very low and very high intakes were associated with higher fracture rates. It may surprise you to learn that this range of optimal intakes was 250-650mg/day for women and 275-780mg/day for men. In the discussion the authors suggest that policy makers rethink the dietary reference intakes for calcium and the policy of milk promotion in developing countries. These results provide evidence that older Chinese men and women eating a plant-based diet may require half as much calcium than their Western counterparts for fracture prevention – approximately 400mg per day. A typical whole foods plant based diet provides at least 500mg of calcium per day and more often 700-800g without having to reach for calcium fortified foods.

Calcium supplements are not effective in preventing osteoporosis and clinical trials have observed an increase in kidney stones and cardiovascular events. Australian doctors are now being urged to consider the risks and benefits before recommending calcium tablets. Osteoporosis is not caused by calcium deficiency and it is not prevented by calcium supplements. See Osteoporosis page. Getting enough calcium on a dairy-free diet of whole plant foods is a non-issue and there is no need to consume plant ‘milks’ for calcium.

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Page substantially revised 9 December 2019
Page last updated 30 December 2019
Resources updated 8 March 2024

Iodine

Iodine is necessary for the production of thyroid hormones. Severe iodine deficiency results in enlargement of the thyroid gland (goitre) and is of particular concern during pregnancy as it can adversely affect the growth and brain development of the foetus. Historically, Iodine deficiency affected people in regions with iodine deficient soils in the days when eating local was the norm. It was not thought to be an issue in Australia until researchers began measuring iodine levels and found that pregnant women often had levels that were considered mildly deficient. Iodine levels in children in the south east of Australia are lower than in Queensland and Western Australia due relatively low soil iodine levels in the south east. The median iodine intake in Australia is only about 100mcg which makes us mildly iodine deficient. The recommended intake is 150mcg for adults, 220mcg during pregnancy and 270mcg while breast feeding.

Several factors have further reduced national iodine status. The dairy industry stopped using iodine based disinfectant to clean milking equipment. The food industry failed to use iodised salt as processed food overtook salt added in the home as the main source of salt in the Australian diet. The problem is being addressed by legislation requiring bakers to use iodised salt but organic bread is exempt from this regulation and many people are avoiding bread because they are following gluten free, grain free or low-carb diets. We suspect that diets that are nutrient poor in general are a big part of the problem – many people obtain a lot of their calories from meat, dairy, sugar, oil and processed food and eat very few vegetables or other whole plant foods. 95% of Australians do not even get the recommended 5 serves of vegetables plus 2 pieces of fruit per day.

Although it is important to have an adequate iodine intake, particularly during pregnancy and breast feeding, more than 1000mcg per day can be toxic. There was an ‘outbreak’ of iodine poisoning in Australia several years ago when one soy company added too much of the iodine rich seaweed product, Kombu, to one of their soy milks. Many plants, including soy, cruciferous vegetables and flaxseed contain goitrogens, substances which inhibit the utilisation of dietary iodine. These goitrogens are not thought to be a problem at usual levels of intake in persons whose iodine intake is adequate.

We are confident that a whole foods plant based diet can provide adequate iodine in Australia. This style of eating eliminates nutrient-depleted foods such as vegetable oils and includes large volumes of a variety of whole plant foods. Furthermore these foods are sourced from many different regions including Queensland and WA where the soils are richer in iodine. Note there is a scarcity of Australian data on the iodine content of plant foods.The iodine content of land plants is dependent on the iodine content of the soil in the region in which they are grown so it varies across Australia. Be aware that if you use Australian nutrient tracking software many common plant foods have no measurement listed for iodine so it may make your iodine intake appear lower than it is.

We recommend if you are going to add salt to your meals that you use iodised salt rather than ‘gourmet’ salts (however, see our Salt FAQ for more information on why added salt should be minimised). Seaweed products are a rich source of iodine but be aware that Kombu (kelp) contains extreme levels of iodine while Hajiki contains toxic quantities of arsenic. Nori, wakame and dulse are recommended. You can add these to salads or soups a few times a week to boost your iodine intake.

Iodine content of sea vegetables:

  • Nori 15 mcg/g (40mcg per 2.5g sheet)
  • Wakame 220-280 mcg/g (dry weight)
  • Dulse 100 mcg/g (dry weight)
  • Kelp 2100-4300 mcg/g  (too much!)

Women who are breast feeding, pregnant or planning to become pregnant can have their iodine status checked with a urinary iodine measurement (which is not very accurate) or just take an iodine supplement of 150 mcg per day. Supplements are not necessary for women eating a whole food plant-based diet who have a consistently high intake of leafy green vegetables plus regular sea vegetable consumption.

Daily iodine intake:

  • 100 mcg   Average Australian iodine intake
  • 150 mcg   Recommended intake for adults
  • 220 mcg   Recommended intake during pregnancy
  • 270 mcg recommended intake during Breast feeding
  • 90 mcg   Recommended intake for children (1-8yr)
  • 1000 mcg recommended upper limit of intake


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Page created 6 April 2015
Page last updated 25 April 2021

Omega 3 Essential Fatty Acids

A whole foods, plant-based diet provides adequate quantities of omega 3 essential fatty acids. With this dietary pattern, supplements are unnecessary and may be harmful. The alleged health benefits of omega 3 supplements is largely marketing hype and recent research has even questioned the long standing dogma that omega 3 supplements are heart protective. Humans are able to efficiently utilize the type of omega 3’s found in plants. However, excessive dietary omega 6’s inhibits the conversion of these plant omega 3’s into DHA and EPA long chain omega 3’s. Therefore, the ratio of omega 6’s to omega 3’s in the diet may be more important than the total amount of omega 3’s.

Our solution to ensuring optimal omega 3 function is to avoid vegetable oils completely, moderate consumption of most nuts and avocados and consume generous quantities of green leafy and other vegetables. Flaxseed and chia seeds are extremely rich sources of omega 3 fats and the addition of small amounts of these foods to your diet will ensure that your omega 3 intake is more than adequate.

Essential fats

It is often stated that we need fats in our diet and that there is no such thing as a no fat diet. While this is true, adding vegetable oils and high fat foods to the diet is not necessary. All whole plant foods contain small amounts of fats and the diet we advocate provides approximately 10% of calories from the fat, a fair proportion of which are essential fatty acids. This easily meets the human requirement for essential fatty acids (there is no absolute requirement for other fats in the diet).

There are two classes of fatty acids which are essential nutrients – omega 3 and omega 6 fatty acids, and these can only be synthesized by plants. All of the omega 3 oils in the food chain originate from plants. Both plant-based and omnivorous diets provide plenty of omega 6 fats so there is no hype and few supplements for this type of essential fat. While most people equate omega 3’s with fish, they are widely present in plants, with some plants being very rich sources. However the omega 3 fatty acids in plants are present as alpha-linolenic acid (ALA) while the active form in humans and other animals are the longer chain EPA and DHA.

CLASS       PLANT FORM                    ANIMAL FORM
Omega-6    linoleic acid (LA)                 arachidonic acid (AA)
Omega-3    alpha-linolenic acid (ALA)   eicosapentaenoic acid(EPA)
docosahexaenoic acid (DHA)

AA and EPA/DHA are substrates for cell membrane components and a large group of signaling molecules called eicosanoids that have powerful local effects in many different organs. The omega 6’s tend to promote inflammation and blood clotting and over production is associated with chronic disease whereas the omega 3’s tend to have the opposite effect. The AA found in animal products is one of the features that makes these foods pro-inflammatory. The anti-inflammatory, anti-thrombotic effect of omega 3 derived molecules provides a theoretical framework for therapeutic use of EPA/DHA supplements, although clinical trials with these supplements have found limited benefits.

We have an enzyme that can convert the ALA (from plants) into the EPA and DHA (active form) with reasonable efficiency. The problem is that this same enzyme also processes the other class of essential fatty acids, the omega 6 fatty acids, and the two classes of fatty acids are said to “compete” for this enzyme. An overload of omega 6’s will therefore reduce the activation of plant omega 3’s. We actually need more dietary omega-6s than omega-3s but not too much more. It is recommended that the current vegetarian and vegan intake (13:1) be reduced to 4:1 or less. This ratio is more important than the actual quantity of omega 3 fats in the diet.

The usual Australian diet is low in vegetable sources of omega 3’s and has huge quantities of omega 6s from vegetable oils. The solution is to avoid vegetable oils completely, moderate your intake of most nuts and avocados (which are high in omega 6’s) and to eat generous quantities of green leafy and other vegetables. Flaxseed, chia seeds are extremely rich sources of omega 3 fats and the addition of small amounts of these foods to your diet will ensure that your omega 3 intake is more than adequate. Walnuts and hemp seeds are a moderately rich source of omega 3’s. Eat the whole seed rather than just the oil – flaxseed for example is also rich in other substances known to promote health such as lignans.

Omega 6 : omega 3 ratios of common foods:

Peanut              no omega 3
Sunflower oil     very high
Almonds          2000:1
Cashews           125:1
Avocado             15:1
Olive oil              13:1
Macadamia         6:1
Soybeans            6:1
Walnuts               4:1
Hemp seed         3:1
Canola oil           2:1
Green leafies*    1:1
Chia seed          1:3
Flax seed           1:4

*Green leafy vegetables are low in fat therefore it takes a lot of them to have a meaningful effect on your omega 3 intake.

You may read that our bodies cannot efficiently convert the plant omega 3 (ALA) into the animal (long-chain) omega 3 (EPA and DHA found in fish and lean meats). If this were true then it would make us obligate carnivores like cats who lack the ability to utilize plant forms of the omega 6 fatty acids and therefore must obtain arachidonic acid from meat. There is another viewpoint from which to consider the apparent inefficiency of EPA and DHA production in the human body and that is that we are not cold water fish. Our cell membranes are not meant to contain high levels of EPA and DHA except for a few special cell types. Creating abnormally high levels of any nutrient or substrate within the body always has consequences. High intakes of ALA from plants is safe because the body can choose how much to convert into EPA and DHA.

There is emerging evidence that there are health risks associated with high intakes of long chain omega 3s. There is an increased risk of diabetes associated with both fish oil supplements and high consumption of fish. Clinical trials of fish oil supplements have also found an increased risk of prostate cancer (see Sorongon-Legaspi et al 2013). High doses of fish oils inhibit the function of platelets (involved in blood clotting) and therefore increase the risk of serious haemorrhages.

The long standing belief that fish oil supplements reduce heart risk has been refuted by several recent studies including this one, n–3 Fatty Acids in Patients with Multiple Cardiovascular Risk Factors, published in the New England Journal of Medicine. The evidence for any other significant benefits from taking fish oil supplements is also becoming weaker. Fish oil is a concentrated source of fat soluble persistent organic pollutants such as PCBs. If you do choose to take a DHA/EPA omega 3 supplement you can use microalgae derived DHA. However, when eating a low-fat whole food plant-based diet with no added oils (which is a diet not too high in omega 6s and that provides a healthful omega 6:3 ratio) then we consider it not necessary to take a long chain omega 3 supplement.

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Page created 22 June 2013
Last updated 1 July 2019

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

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Last updated 11 April 2015