<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2019-09-03</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000351834</issuerCik>
        <issuerName>SunOpta Inc.</issuerName>
        <issuerTradingSymbol>STKL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001787240</rptOwnerCik>
            <rptOwnerName>Huckins Scott E.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>7301 OHMS LANE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 600</rptOwnerStreet2>
            <rptOwnerCity>EDINA</rptOwnerCity>
            <rptOwnerState>MN</rptOwnerState>
            <rptOwnerZipCode>55439</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CFO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Shares</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Restricted Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F3"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>173319</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>2.38</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2029-09-03</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>262182</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Performance Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F7"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F6"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>173319</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Performance Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F7"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F8"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F6"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>173319</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The Restricted Stock Units vest in three equal annual installments beginning on September 3, 2020, subject to the continued employment of the reporting person through each such vesting date.</footnote>
        <footnote id="F2">The Restricted Stock Units do not have an expiration date.</footnote>
        <footnote id="F3">Each Restricted Stock Unit represents a contingent right to receive one share of STKL common stock.</footnote>
        <footnote id="F4">The Company granted the reporting person 262,182 time-based stock options (the &quot;Special Stock Options&quot;) as of September 3, 2019. The vesting of the Special Stock Options is subject to the reporting person's continued employment with the Company through September 3, 2022.</footnote>
        <footnote id="F5">The reporting person was granted 173,319 performance stock units (the &quot;Special Performance Units&quot;) as of September 3, 2019. The vesting of the Special Performance Units is subject to (i) the satisfaction of certain fiscal year EBITDA and (ii) the reporting person's continued employment with the Company through the applicable vesting date. For the EBITDA performance conditions, 57,773 of the Special Performance Units will vest upon the Company achieving annual adjusted EBITDA of $80,000,000, another 57,773 will vest upon the Company achieving annual adjusted EBITDA of $110,000,000, and the final 57,773 will vest upon the Company achieving annual adjusted EBITDA of $140,000,000, and subject to continued employment through the end of the fiscal year the EBITDA performance condition is achieved.</footnote>
        <footnote id="F6">The Performance Stock Units do not have an expiration date.</footnote>
        <footnote id="F7">Each Performance Stock Unit represents a contingent right to receive one share of STKL common stock.</footnote>
        <footnote id="F8">The reporting person was granted 173,319 performance stock units (the &quot;Special Performance Units&quot;) as of September 3, 2019. The vesting of the Special Performance Units is subject to (i) the satisfaction of certain stock price performance conditions and (ii) the reporting person's continued employment with the Company through the applicable vesting date. For the stock price performance conditions, 57,773 of the Special Performance Units will vest upon achieving a volume weighted average trading stock price of $5.00 per share, another 57,773 will vest upon achieving a stock price of $9.00 per share, and the final 57,773 will vest upon achieving a stock price of $14.00 per share, in each case for 20 consecutive trading days and subject to continued employment through the date the stock price performance condition is achieved.</footnote>
    </footnotes>

    <remarks>Exhibit List
         Exhibit 24: Power of Attorney</remarks>

    <ownerSignature>
        <signatureName>/s/ Jill Barnett, attorney-in-fact</signatureName>
        <signatureDate>2019-09-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
