Australia lagged the rest of the world in approving the sale of hemp seeds for human consumption in late 2017. Prior to this, the sale of hemp seeds was legal, provided it was for use in cosmetics or another non-food use. Hemp seeds are produced from non-intoxicating varieties of the hemp plant and do not contain significant cannabinoids.

Hemp seeds will become widely available in 2018 and there will be many new products coming onto the market and many nutrition claims, possibly ‘superfood’ status. As with any other edible seeds, we recommend that if you are going to eat hemp seeds, that you eat whole or ground seeds and not processed food products such as hemp seed protein and hemp seed oil.

We have reviewed the nutrition composition of hemp seeds and compared them to several other nuts and seeds, particularly regarding their omega 3 essential fatty acid content. The USDA data that we used was similar to the nutrient data listed on two different brands of hemp seed in retail outlets.

Protein and other nutrients:

• Hemp seeds are much higher in protein (22% of calories) than flax or chia but lower than legumes.
• Flax and chia are far higher in dietary fibre than hemp and the fibre in flax (lignins) assists the body to excrete excess estrogens.
• The calcium content of the seeds ranged from very high for chia, moderate for flax and low for hemp.

Omega 3’s (alpha linolenic acid):

Many people have sub-optimal intakes of omega 3’s and perhaps more importantly, unfavourably high ratios of dietary omega 6 to omega 3. This is the result of low intakes of omega 3 rich plants combined with high intakes of omega 6 rich plants such as nuts, seeds, avocados as well as vegetable oils. An optimal omega 6 to 3 ratio is 4:1 or less.

For a whole food omega 3 source to bring the dietary omega 6 to 3 ratio into balance, it needs to have a ratio well below the target of 4:1. Flax (ratio 1:4) and chia (ratio 1:3) have more omega 3’s than 6’s and are therefore excellent sources of omega 3 fats. Hemp seeds (3:1) and walnuts (4:1) might be considered good sources on their own, but not good enough to compensate for the omega 6 rich foods in the typical plant-based diet. For more on omega 3’s see our Omega-3 Essential Fatty Acids page.

The following table gives comparative data for four high omega 3 nuts and seeds:

The Australian recommended intake range of omega 3 fatty acids is 1-2 grams per day (see Nutrient Reference Values for Australia and New Zealand).
This is met by consuming 10g flax or chia per day.

Hemp seeds have a more favourable fatty acid profile than most other nuts and seeds but fall well behind flax seed and chia seed as a concentrated source of omega 3 fats. They have a mild taste and relatively soft texture which makes them suitable as an ingredient in a variety of dishes. Hemp seeds, like other nuts and seeds, can be a healthy addition to a whole foods, plant-based diet but are best consumed in small amounts.

See also:

• Omega-3 essential fatty acids

Resources

• National Health and Medical Research Council. (2006). Nutrient Reference Values for Australia and New Zealand: Including Recommended Dietary Intakes. Canberra: NHMRC
• USDA Food Composition Databases – do a Food Search and select Standard Reference. If your food doesn’t come up in the search change to using All Data Sources (which gives you branded products)

Page created 26 February 2018
Page last updated 2 March 2018

• Omega 6:3 ratios
• Resources

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 and hemp 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 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.

See related pages:

• Are hemp seeds a good source of omega-3?
• No Oil
• Vitamins and Minerals
• Why do we recommend a low-fat diet?

Resources

• DHA: On Further Thought – Dr. Michael Klaper (20 min video) **NEW**
• Do Vegans Need DHA Supplements? – Jeff Nelson (1hr video) Looks at the research around omega 3 fatty acids, including the body’s ability to convert omega 3 to the long chain form and the risks and benefits of DHA supplementation. 
• Increased Omega-3 Fatty Acids Intake Useless for CVD – Pam Popper (12 min video). Pam regularly reviews the science on omega 3 supplements and continues to find there is no benefit in supplementing.
• Fuhrman’s DHA Is A Hoax – (2019) Jeff Nelson looks at the evidence behind Dr Fuhrman’s recommendation to take DHA supplements for brain health and finds there is no credible evidence. See also DHA Reconsidered – Michael Klaper MD
• No benefit of omega-3 supplements for depression or anxiety – Robyn Chuter **New** (2019)
• Dr. Greger Fan Questions Supplementing with EPA and DHA – Youcef Banouni takes a closer look at the evidence presented by Dr Greger and finds this recommendation has little relevance to those eating a whole food plant-based diet
• Do You Need to Supplement With EPA and DHA If You Follow a Whole Food Plant-Based Lifestyle? – Dominic Marro, RD (2016)
• Omega 3 – Discussion by Jeff Novick, RD on the conversion rate of ALA in the McDougall Discussion forum
• Dr Michael Greger summarises the information on fish oil and why it should be avoided (contains links to numerous videos that link fish and fish oil supplements to persistent organic pollutants)

Peer-reviewed articles

• The Risk and Prevention Study Collaborative Group. (2013). n–3 Fatty Acids in Patients with Multiple Cardiovascular Risk Factors. New England Journal of Medicine, 368(19), 1800-1808 – “…there was no significant benefit of n−3 fatty acids in reducing the risk of death from cardiovascular causes”
• Hooper, L., et al. (2006). Risks and benefits of omega 3 fats for mortality, cardiovascular disease, and cancer: systematic review. BMJ, 332(7544), 752-760 – “…omega 3 fats do not have a clear effect on total mortality, combined cardiovascular events, or cancer”.
• Kaushik, M., et al. (2009). Long-chain omega-3 fatty acids, fish intake, and the risk of type 2 diabetes mellitus. American Journal of Clinical Nutrition, 90(3), 613-620 – “…higher fish and long-chain omega-3 fatty acid consumption appears to be associated with a modestly but significantly higher incidence of T2DM”
• Simopoulos, A. P. (2008). The importance of the omega-6/omega-3 fatty acid ratio in cardiovascular disease and other chronic diseases. Experimental Biology and Medicine, 233(6), 674-688.
• Sorongon-Legaspi, M. K., Chua, M., Sio, M. C., & Morales, M., Jr. (2013). Blood level omega-3 Fatty acids as risk determinant molecular biomarker for prostate cancer. Prostate Cancer, 2013, 875615.
• Welch, A. A., et al. (2010). Dietary intake and status of n-3 polyunsaturated fatty acids in a population of fish-eating and non-fish-eating meat-eaters, vegetarians, and vegans and the product-precursor ratio [corrected] of alpha-linolenic acid to long-chain n-3 polyunsaturated fatty acids: results from the EPIC-Norfolk cohort. American Journal of Clinical Nutrition, 92(5), 1040-1051.

Page created 22 June 2013
Last updated 1 July 2019

• Resources

Specific vitamins and minerals:

• Vitamin B12
• Vitamin D
• Calcium
• Iron
• Iodine
• Omega-3 essential fatty acids

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

Last updated 11 April 2015