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Omega-3 fatty acids are a class of saturated fatty acids, which are essential for human health.
Answer: False
Explanation: Omega-3 fatty acids are polyunsaturated, not saturated, and are essential for human health.
The defining chemical characteristic of omega-3 fatty acids is a double bond located three atoms away from the terminal methyl group.
Answer: True
Explanation: The defining characteristic of omega-3 fatty acids is indeed a double bond positioned three carbon atoms from the methyl end of the molecule.
Docosahexaenoic acid (DHA) has 20 carbon atoms and 5 double bonds.
Answer: False
Explanation: Docosahexaenoic acid (DHA) has 22 carbon atoms and 6 double bonds. Eicosapentaenoic acid (EPA) has 20 carbon atoms and 5 double bonds.
Unsaturated fatty acids are susceptible to oxidation due to free radical attack at their bis-allylic sites.
Answer: True
Explanation: Unsaturated fatty acids, including omega-3s, are indeed susceptible to oxidation and rancidity because free radicals can attack the atoms at their bis-allylic sites.
The IUPAC recommends using 'ω' (omega) over 'n' in fatty acid nomenclature to identify the highest carbon number.
Answer: False
Explanation: The International Union of Pure and Applied Chemistry (IUPAC) recommends using 'n' over 'ω' (omega) in fatty acid nomenclature to identify the highest carbon number.
All double bonds in naturally-produced omega-3 fatty acids are typically in the trans-configuration.
Answer: False
Explanation: In most naturally-produced omega-3 fatty acids, all double bonds are typically in the cis-configuration, not trans-configuration.
Replacing hydrogen atoms with deuterium atoms at bis-allylic sites can protect omega-3 fatty acids from oxidative damage.
Answer: True
Explanation: Replacing hydrogen atoms with deuterium atoms at the bis-allylic sites of omega-3 fatty acids has been shown to protect them from lipid peroxidation and ferroptosis, which are forms of oxidative damage.
Omega-3 fatty acids occur naturally only in the form of phospholipids.
Answer: False
Explanation: Omega-3 fatty acids occur naturally in two primary forms: triglycerides and phospholipids.
Which of the following is NOT an alternative name for omega-3 fatty acids?
Answer: Omega-6 fatty acids
Explanation: Omega-3 fatty acids are also known as omega-3 oils, ω-3 fatty acids, or n-3 fatty acids. Omega-6 fatty acids are a distinct class of polyunsaturated fatty acids.
What is the defining chemical characteristic of omega-3 fatty acids?
Answer: A double bond located three atoms away from the terminal methyl group.
Explanation: Omega-3 fatty acids are chemically defined by the presence of their first double bond at the third carbon atom when counting from the terminal methyl group.
Which three specific omega-3 fatty acids are primarily involved in human physiology?
Answer: Alpha-linolenic acid (ALA), Eicosapentaenoic acid (EPA), and Docosahexaenoic acid (DHA)
Explanation: Alpha-linolenic acid (ALA), Eicosapentaenoic acid (EPA), and Docosahexaenoic acid (DHA) are the three omega-3 fatty acids most crucial for human physiological processes.
What is the carbon chain length and number of double bonds for Alpha-linolenic acid (ALA)?
Answer: 18 carbon atoms and 3 double bonds
Explanation: Alpha-linolenic acid (ALA) is an 18-carbon fatty acid with three double bonds.
Who first identified fatty acids as essential for health in 1929?
Answer: George and Mildred Burr
Explanation: In 1929, George and Mildred Burr were the first to identify fatty acids as essential for health, coining the term 'essential fatty acids'.
According to IUPAC recommendations, which letter is preferred to identify the highest carbon number of a fatty acid?
Answer: n
Explanation: The International Union of Pure and Applied Chemistry (IUPAC) recommends using the letter 'n' to identify the highest carbon number of a fatty acid, although 'ω' (omega) is also synonymous.
What is a key chemical characteristic of the double bonds in most naturally-produced omega-3 fatty acids?
Answer: They are all in the cis-configuration and interrupted by methylene bridges.
Explanation: In most naturally-produced omega-3 fatty acids, all double bonds are in the cis-configuration and are interrupted by methylene bridges, meaning two single bonds separate each pair of adjacent double bonds.
In what two primary natural forms do omega-3 fatty acids occur?
Answer: Triglycerides and phospholipids
Explanation: Omega-3 fatty acids primarily occur naturally as triglycerides, where three fatty acids are attached to glycerol, and as phospholipids, where two fatty acids are attached to a phosphate group via glycerol.
Alpha-linolenic acid (ALA) is primarily found in marine algae and phytoplankton, while DHA and EPA are found in plants.
Answer: False
Explanation: Alpha-linolenic acid (ALA) is found in plants, whereas docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are primarily found in marine algae and phytoplankton.
The modern diet, with its emphasis on shelf-stable processed foods, has generally increased omega-3 intake due to preservation techniques.
Answer: False
Explanation: The modern diet, particularly with its reliance on shelf-stable processed foods, has generally led to a deficiency of omega-3 fatty acids because they are prone to oxidation and are often removed or degraded during processing.
Salmon, herring, and mackerel are widely available dietary sources of EPA and DHA from oily fish.
Answer: True
Explanation: Salmon, herring, sardines, mackerel, anchovies, and trout are indeed widely available dietary sources of EPA and DHA from oily fish.
Aquaculture is a major consumer of fish oil because farmed marine fish require EPA and DHA supplementation in their feed.
Answer: True
Explanation: Aquaculture is a significant consumer of fish oil because farmed marine fish necessitate EPA and DHA supplementation in their feed to achieve omega-3 levels comparable to wild-caught fish.
Krill oil contains astaxanthin, an antioxidant that may act synergistically with EPA and DHA.
Answer: True
Explanation: Krill oil contains astaxanthin, a marine-source carotenoid antioxidant, which preliminary studies suggest may act synergistically with EPA and DHA, and may also offer greater bioavailability for these fatty acids.
Environmental concerns about krill harvesting are minimal because krill are not a primary food source for many ocean-based species.
Answer: False
Explanation: Environmental concerns about krill harvesting are significant because krill are a mainstay of the diets of many ocean-based species, including whales, raising worries about ecosystem impact.
Perilla, chia seeds, and flax are plant-based sources rich in ALA.
Answer: True
Explanation: Perilla, chia seeds, and flax (linseed) are indeed plant-based sources rich in alpha-linolenic acid (ALA).
The longer-chain omega-3 fatty acids, EPA and DHA, are naturally produced by land plants.
Answer: False
Explanation: The longer-chain omega-3 fatty acids, EPA and DHA, are naturally produced only by marine algae and phytoplankton, not by land plants.
Genetically modified plants like *Camelina sativa* are being developed to produce EPA and DHA.
Answer: True
Explanation: Transgenic initiatives have successfully developed genetically modified plants, such as *Camelina sativa* and canola strains, to produce EPA and DHA.
Feeding hens a diet rich in fish oils or flax can increase the omega-3 content in eggs.
Answer: True
Explanation: The omega-3 fatty acid content in eggs can be increased by feeding hens a diet rich in sources like greens, insects, fish oils, flax, or canola seeds.
Grass-fed beef typically has a higher omega-6:omega-3 ratio compared to grain-fed beef.
Answer: False
Explanation: Grass-fed beef typically has a healthier, lower omega-6:omega-3 ratio (around 2:1) compared to grain-fed beef (around 4:1).
A notable trend in the early 21st century was the fortification of various foods with omega-3 fatty acids.
Answer: True
Explanation: The early 21st century saw a notable trend of fortifying various foods with omega-3 fatty acids to increase their dietary intake among consumers.
Where are docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) primarily found in nature?
Answer: Marine algae and phytoplankton
Explanation: Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are primarily synthesized by marine algae and phytoplankton, forming the base of their presence in the marine food web.
How has the modern diet, particularly processed foods, generally affected omega-3 intake?
Answer: It has led to a deficiency of omega-3 in manufactured foods.
Explanation: The shift towards shelf-stable processed foods in the modern diet has generally resulted in a deficiency of omega-3 fatty acids in manufactured foods due to their susceptibility to oxidation during processing.
Which of the following fish are widely available dietary sources of EPA and DHA?
Answer: Salmon, Herring, and Mackerel
Explanation: Salmon, herring, and mackerel are among the most widely available oily fish that serve as rich dietary sources of EPA and DHA.
Why is aquaculture a major consumer of fish oil?
Answer: Farmed marine fish require EPA and DHA supplementation in their feed.
Explanation: Aquaculture is a significant consumer of fish oil because farmed marine fish require EPA and DHA supplementation in their feed to achieve desirable omega-3 levels, making up a significant portion of the global fish oil supply.
What is a potential advantage of krill oil over fish oil, according to preliminary studies?
Answer: It contains astaxanthin, an antioxidant, and its DHA/EPA are more bio-available.
Explanation: Preliminary studies suggest that krill oil may offer advantages over fish oil, including potentially higher bioavailability of DHA and EPA, and the presence of astaxanthin, a marine carotenoid antioxidant.
Which of the following is a plant-based source rich in ALA?
Answer: Chia seeds
Explanation: Chia seeds are a notable plant-based source rich in alpha-linolenic acid (ALA), along with other examples like perilla and flaxseed.
What are the natural sources of the longer-chain omega-3 fatty acids, EPA and DHA?
Answer: Only marine algae and phytoplankton
Explanation: The longer-chain omega-3 fatty acids, EPA and DHA, are naturally produced exclusively by marine algae and phytoplankton, forming the basis of their presence in marine ecosystems.
How can the omega-3 content of eggs be enhanced?
Answer: By feeding hens a diet rich in greens, insects, fish oils, flax, or canola seeds.
Explanation: The omega-3 fatty acid content in eggs can be enhanced by supplementing hens' diets with ingredients rich in omega-3s, such as greens, insects, fish oils, flax, or canola seeds.
How does grass-fed beef compare to grain-fed beef in terms of omega-6:omega-3 ratio?
Answer: Grass-fed beef has a healthier, lower omega-6:omega-3 ratio.
Explanation: Grass-fed beef is characterized by a healthier, lower omega-6:omega-3 ratio (approximately 2:1) compared to grain-fed beef (typically 4:1), along with higher levels of other beneficial nutrients.
Animals can synthesize the essential omega-3 fatty acid ALA if other omega-3s are available in their diet.
Answer: False
Explanation: Animals generally cannot synthesize the essential omega-3 fatty acid ALA; it must be obtained through their diet. They can, however, convert ALA into EPA and DHA.
Humans are unable to synthesize omega-3 and omega-6 fatty acids because they lack the necessary desaturase enzyme.
Answer: True
Explanation: Humans are unable to synthesize omega-3 and omega-6 polyunsaturated fatty acids because they lack the desaturase enzyme required to insert double bonds at the ω6 and ω3 positions.
The ratio of ingested omega-3 to omega-6 fatty acids influences the type and rate of eicosanoid production.
Answer: True
Explanation: Omega-3 and omega-6 fatty acids compete for the same metabolic enzymes, and their ingested ratio directly influences the type and rate of eicosanoid production, thereby affecting the body's metabolic and inflammatory state.
The conversion efficiency of short-chain ALA to long-chain EPA and DHA is typically greater in men than in women.
Answer: False
Explanation: The conversion efficiency of short-chain ALA to long-chain EPA and DHA is generally greater in women than in men, possibly due to higher activity of desaturase enzymes.
A healthy ratio of omega-6 to omega-3 fatty acids in Western diets is typically between 10:1 and 30:1.
Answer: False
Explanation: While Western diets often exhibit omega-6 to omega-3 ratios between 10:1 and 30:1, a healthy ratio is generally considered to be much lower, ranging from 1:1 to 4:1.
DHA is transported across the blood-brain barrier as free fatty acid molecules.
Answer: False
Explanation: DHA is transported across the blood-brain barrier in the form of lysophosphatidylcholine by the specific membrane transport protein MFSD2A, not as free fatty acid molecules.
Why are omega-3 and omega-6 polyunsaturated fatty acids considered essential for humans?
Answer: The human body lacks the desaturase enzyme to insert double bonds at the ω6 and ω3 positions.
Explanation: Omega-3 and omega-6 polyunsaturated fatty acids are essential for humans because the body lacks the desaturase enzyme required to introduce double bonds at the ω6 and ω3 positions, making dietary intake necessary.
How does the ratio of ingested omega-3 to omega-6 fatty acids impact the body?
Answer: It directly influences the type and rate of eicosanoid production.
Explanation: The ratio of ingested omega-3 to omega-6 fatty acids is critical because these fatty acids compete for the same metabolic enzymes, directly influencing the type and rate of eicosanoid production, which in turn affects the body's metabolic and inflammatory state.
What is the typical efficiency of converting short-chain ALA to long-chain EPA and DHA in humans?
Answer: Typically below 5%
Explanation: Humans typically convert short-chain alpha-linolenic acid (ALA) to the longer-chain eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) with an efficiency generally below 5%.
What is considered a healthy ratio of omega-6 to omega-3 fatty acids by some authors?
Answer: 1:1 to 1:4
Explanation: Some authors suggest a healthy ratio of omega-6 to omega-3 fatty acids ranges from 1:1 to 1:4, or a 4:1 ratio, contrasting sharply with typical Western diets.
How is DHA transported across the blood-brain barrier?
Answer: As lysophosphatidylcholine by the MFSD2A transport protein.
Explanation: DHA is transported into the brain across the blood-brain barrier as lysophosphatidylcholine, facilitated by the specific membrane transport protein MFSD2A.
The U.S. FDA granted 'qualified health claim' status to EPA and DHA omega-3 fatty acids in 2004 regarding the reduction of coronary heart disease risk.
Answer: True
Explanation: In 2004, the U.S. FDA granted a 'qualified health claim' for EPA and DHA omega-3 fatty acids, indicating that supportive but not conclusive research suggests they may reduce the risk of coronary heart disease.
The Canadian Food Inspection Agency permits a claim that DHA supports brain, eye, and nerve development primarily in adults.
Answer: False
Explanation: The Canadian Food Inspection Agency permits a claim that DHA supports the normal physical development of the brain, eyes, and nerves, but primarily in children under two years of age, not adults.
Seal oil is permitted for import into the European Union as a source of omega-3 fatty acids.
Answer: False
Explanation: Seal oil is not permitted for import into the European Union, and its sale is illegal in the United States under the Marine Mammal Protection Act.
What was the U.S. FDA's 'qualified health claim' for EPA and DHA omega-3 fatty acids issued in 2004?
Answer: Supportive but not conclusive research shows consumption may reduce the risk of coronary heart disease.
Explanation: The U.S. FDA's 2004 'qualified health claim' for EPA and DHA stated that 'supportive but not conclusive research shows that consumption of EPA and DHA [omega-3] fatty acids may reduce the risk of coronary heart disease'.
What is the legal status of seal oil sale in the United States?
Answer: It is illegal under the Marine Mammal Protection Act.
Explanation: The sale of seal oil in the United States is illegal under the Marine Mammal Protection Act, and it is also not permitted for import into the European Union.
A 2020 review concluded that EPA and DHA supplements do not appear to improve overall mortality or cardiovascular health.
Answer: True
Explanation: A 2020 review of moderate and high-quality evidence concluded that EPA and DHA supplements do not appear to improve overall mortality or cardiovascular health.
Omega-3 supplementation at 4 grams per day is recommended by the American Heart Association for reducing blood triglycerides.
Answer: True
Explanation: The American Heart Association (2019) recommends omega-3 fatty acid supplementation at a dose of 4 grams per day for reducing levels of blood triglycerides.
Omega-3 supplementation, especially at doses greater than one gram per day, is associated with a decreased risk of atrial fibrillation.
Answer: False
Explanation: Omega-3 supplementation, particularly marine omega-3s at doses greater than one gram per day, is associated with an *increased* risk of atrial fibrillation, not a decreased risk.
A 2019 review found that omega-3 supplements have no effect on the prevention and treatment of type 2 diabetes.
Answer: True
Explanation: A 2019 review concluded that omega-3 supplements have no effect on the prevention and treatment of type 2 diabetes, although a later meta-analysis indicated positive effects on some diabetes biomarkers.
What did a 2020 review conclude about EPA and DHA supplements for overall cardiovascular health and mortality?
Answer: They have no effect on overall mortality or cardiovascular health.
Explanation: A 2020 review of moderate and high-quality evidence concluded that EPA and DHA omega-3 polyunsaturated fatty acid supplements do not appear to improve overall mortality or cardiovascular health.
According to the American Heart Association (2019), what dose of omega-3 fatty acid supplementation may be effective for reducing blood triglycerides?
Answer: 4 grams per day
Explanation: The American Heart Association (2019) recommends omega-3 fatty acid supplementation at a dose of 4 grams per day as potentially effective for reducing blood triglyceride levels.
What is a notable adverse effect associated with marine omega-3 supplementation at doses greater than one gram per day?
Answer: Increased risk of atrial fibrillation
Explanation: A notable adverse effect associated with marine omega-3 supplementation, particularly at doses exceeding one gram per day, is an increased risk of atrial fibrillation, especially in individuals with high blood triglycerides.
According to a 2019 review, what was the conclusion regarding omega-3 supplements for the prevention and treatment of type 2 diabetes?
Answer: They have no effect on the prevention and treatment of type 2 diabetes.
Explanation: A 2019 review concluded that omega-3 supplements have no effect on the prevention and treatment of type 2 diabetes, although a later meta-analysis suggested positive effects on some diabetes biomarkers.
DHA is a minor structural component in the human brain.
Answer: False
Explanation: Docosahexaenoic acid (DHA) is a major structural component and is found in high abundance in the human brain.
There is clear evidence that marine-derived omega-3 supplementation improves cognitive recovery after stroke.
Answer: False
Explanation: A 2022 Cochrane review found no clear evidence that marine-derived omega-3 supplementation improves cognitive or physical recovery after stroke, nor does it prevent recurrence or mortality.
Long-chain omega-3 supplements have been conclusively shown to have a clinically meaningful effect on preventing or treating depression and anxiety.
Answer: False
Explanation: Recent systematic and Cochrane reviews concluded that long-chain omega-3 supplements likely have little or no clinically meaningful effect on preventing or treating depression or anxiety, with low to very low certainty in the findings.
What is the role of DHA in the human brain?
Answer: It is a major structural component found in high abundance.
Explanation: Docosahexaenoic acid (DHA) is a major structural component of the human brain, where it is found in high abundance, underscoring its critical role in brain health and function.
What did a 2022 Cochrane review find regarding marine-derived omega-3 supplementation after a stroke?
Answer: No clear evidence of improved cognitive/physical recovery or prevention of recurrence/mortality.
Explanation: A 2022 Cochrane review found no clear evidence that marine-derived omega-3 supplementation improves cognitive or physical recovery, or prevents recurrence or mortality, following a stroke.
What is the scientific consensus on omega-3 PUFA supplements for treating Alzheimer's disease or dementia?
Answer: There is no convincing evidence that they are effective in treating Alzheimer's disease or dementia.
Explanation: The scientific consensus is that there is no convincing evidence that omega-3 PUFA supplements are effective in treating Alzheimer's disease or dementia, nor do they deter cognitive decline in older adults.
Omega-3 fatty acid supplementation has been conclusively shown to prevent various cancers and reduce all-cause mortality.
Answer: False
Explanation: There is insufficient evidence to conclude that omega-3 fatty acid supplementation prevents various cancers or reduces all-cause mortality; the association remains inconclusive.
Omega-3 fatty acids have shown consistent, modest evidence for reducing symptoms of rheumatoid arthritis.
Answer: True
Explanation: There is consistent, albeit modest, evidence that omega-3 fatty acids can reduce symptoms of rheumatoid arthritis, such as joint swelling, pain, and morning stiffness, and may decrease the need for NSAIDs.
The American College of Rheumatology advises that fish oils for rheumatoid arthritis offer immediate and significant benefits without side effects.
Answer: False
Explanation: The American College of Rheumatology cautions that the effects of fish oils for rheumatoid arthritis may take months to appear, and there are risks of gastrointestinal side effects and potential contamination, contradicting the idea of immediate and significant benefits without side effects.
Omega-3 supplementation during pregnancy may reduce the risk of perinatal death and low body weight babies.
Answer: True
Explanation: A 2018 Cochrane review suggested that omega-3 fatty acids during pregnancy may reduce the risk of perinatal death and low body weight babies, among other potential favorable effects.
Omega-3 PUFA supplementation has been found to prevent or slow the progression of macular degeneration.
Answer: False
Explanation: Omega-3 PUFA supplementation has been found to have no effect on preventing or slowing the progression of macular degeneration or the development of visual loss.
Omega-3 supplements have been shown to prevent asthma attacks in children as of 2015.
Answer: False
Explanation: As of 2015, there was no evidence to suggest that taking omega-3 supplements can prevent asthma attacks in children.
For rheumatoid arthritis, what has tentative evidence suggested about omega-3 fatty acids?
Answer: They can lower inflammation levels and modestly reduce symptoms like joint swelling and pain.
Explanation: Tentative evidence suggests that omega-3 fatty acids can lower inflammation markers and modestly reduce symptoms of rheumatoid arthritis, such as joint swelling, pain, and morning stiffness.
What caution does the American College of Rheumatology provide regarding fish oils for rheumatoid arthritis?
Answer: Effects may take months to appear, and there are risks of gastrointestinal side effects and potential contamination.
Explanation: The American College of Rheumatology cautions that while fish oils may offer modest benefits for rheumatoid arthritis, their effects can take months to manifest, and there are risks of gastrointestinal side effects and potential contamination.
What did a 2018 Cochrane review suggest about omega-3 fatty acids during pregnancy?
Answer: They may reduce the risk of perinatal death and low body weight babies.
Explanation: A 2018 Cochrane review indicated that omega-3 fatty acids during pregnancy may reduce the risk of perinatal death and low body weight babies, and potentially increase the likelihood of large for gestational age babies.
What is the effect of omega-3 PUFA supplementation on preventing or slowing macular degeneration?
Answer: It has no effect on preventing or slowing the progression of macular degeneration.
Explanation: Omega-3 PUFA supplementation has been found to have no effect on preventing or slowing the progression of macular degeneration or the development of visual loss.
Publication bias is a factor that can explain heterogeneity in results regarding omega-3 efficacy for depressed symptoms.
Answer: True
Explanation: Publication bias, characterized by shorter treatment trials often reporting increased efficacy, is noted as a factor explaining heterogeneity in results regarding omega-3 efficacy for depressed symptoms.
What methodological issue is noted to affect the interpretation of omega-3 research, particularly regarding efficacy for depressed symptoms?
Answer: Publication bias, where shorter treatment trials were often associated with increased reported efficacy.
Explanation: Publication bias, characterized by shorter treatment trials often reporting increased efficacy, is a noted methodological issue affecting the interpretation of omega-3 research.